Dry Fasting: Is It Worth It?

Today’s post is about dry fasting. I’ve covered plenty of other aspects of intermittent fasting, including recommendations around longer fasts, but lately I’ve gotten enough questions about this particular angle that I thought I’d address it.

Dry fasting is going without both food and fluid. That means no coffee, no tea, no broth, and no water or liquid of any kind (except the saliva you manage to produce). It’s an extreme type of fast whose fans and practitioners are adamant that it can resolve serious health issues. But does it? Is it safe? And what kind of research is available on it?

Where Does the Idea of Therapeutic Dry Fasting Come From?

The main proponent of dry fasting is a Russian doctor named Sergei Filonov. Filonov is still practicing from what I can tell, somewhere in the Altai mountains that span Central Asia. I found a very rough English translation of his book—Dry Medical Fasting: Myths and Realities. Difficult to read in full because it’s not a professional translation, but manageable in small chunks.

His basic thesis is that dry fasting creates a competitive environment between healthy cells, unhealthy cells, and pathogens for a scarce resource: water. The dry fast acts as a powerful selective pressure, allowing the strong cells to survive and the weak and dangerous cells to die off. The end result, according to Filonov, is that the immune system burns through the weak cells for energy and to conserve water for the viable cells, leading to a stronger organism overall. He points to how animals in nature will hole up in a safe, comfortable spot and take neither food nor water when recovering from serious conditions, illness, or injuries that prevent them from moving around. But when they’re able to move while recovering from more minor issues, they’ll drink water and abstain from food. I’m partial to this naturalistic line of thought, but I don’t know if the claims about animal behavior during sickness are true.

Another claim is that dry fasting speeds up fat loss relative to fasts that include water. There may be something to this, as body fat is actually a source of “metabolic water”—internal water the body can turn to when exogenous water is limited. Burning 100 grams of fat produces 110 grams of water, whereas burning the same amount of carbohydrate produces just 50 grams of water.

Are There Any Dry Fasting Studies?

Unfortunately, we don’t have many long term dry fasting studies. In fact, we have one 5-day study in healthy adults. For five days, ten healthy adults refrained from eating food or drinking water. Multiple physiological parameters were tracked daily, including bodyweight, kidney function, heart rate, electrolyte status, and circumference of the waist, hip, neck, and chest.

Participants lost weight (over 2 pounds a day) and inches off of various circumferences, including waist, hip, neck, and chest. The drop in waist circumference was particularly large—about eight centimeters by day five. Blood pressure, heart rate, oxygen saturation, sodium and potassium levels, creatinine, and urea all remained stable throughout the study. Creatinine clearance—which can be a marker of muscle breakdown but also a normal artifact of fasting—increased by up to 167%.

The most voluminous research we have on dry fasting is the Ramadan literature. During the month of Ramadan, practicing Muslims complete a daily dry fast—from sunup to sundown—every single day. They eat no food and drink no fluids during daylight hours, which, in the countries where Islam originally arose, run about 15-16 hours. These are shorter dry fasts than the 5-day fast detailed above.

What happens to health markers during Ramadan? Mostly good things.

A 15- or 16- hour dry fast isn’t very extreme, even in the hot climates of the Near East. Two or three day-long dry fasts, particularly in hot weather, is another thing entirely. What works and is safe across 16 hours might not be safe or effective over three or four days.

I wonder if there’s a genetic component to dry fasting tolerance, too. Have populations who’ve spent thousands of years in hot, dry, desert-like climates developed greater genetic tolerance of periods without water? I find it likely, though I haven’t seen any genetic data one way or the other. It’s an interesting thing to ponder.

Is Dry Fasting Safe?

Obviously, skipping water can be dangerous. While we’ve seen people go without food for as long as a year (provided you have enough adipose tissue to burn, take vitamins and minerals, and are under medical supervision), going without water is a riskier proposal. The number I’ve always heard was three weeks without food, three days without water, though I’ve never really seen it substantiated or sourced.

One reason I’m skeptical of “three days” as a hard and fast rule is that most cases of people dying of dehydration occur in dire circumstances. People are lost out in the wilderness, hiking around in vain trying to find their way back to the trailhead. They’re thrown in jail after a night out drinking and forgotten by the guards for three days. They’re spending 24 hours dancing in a tent in the desert on multiple psychoactive drugs. These are extreme situations that really increase the need for water. Your water requirements will be much higher if you’re hiking around in hot weather bathing in stress-induced cortisol and adrenaline, or dancing hard for hours on end. Very rarely do we hear of people setting out to abstain from water on purpose for medical benefits, water on hand in case things go south, and ending up dehydrated. Part of the reason is that very few people are dry fasting, so the pool of potential evidence is miniscule. I imagine this last group will have more leeway.

Still, if you’re going to try dry fasting, you have to take some basic precautions.

6 Precautions To Take When Dry Fasting

1. Get Your Doctor’s Okay

Sure, most will be skeptical at best, but I’d still advise not skipping this step—particularly if you have a health condition or take any kind of medication. Diuretics (often used for blood pressure management), for one example, add another layer to this picture.

2. No Exercise

Avoid anything more intense than walking. For one, the hypohydration will predispose you to middling results, increasing cortisol and reducing testosterone. Two, the hypohydration may progress rapidly to dehydration. If you’re going to exercise during a dry fast, “break” the fast with water first and then train.

3. Keep It Brief

Yes, there was the 5-day study, but those people were being monitored by doctors every single day. I’d say 16-24 hours is a safe upper limit and probably provides most of the benefits (as Ramadan literature shows). Any longer, buyer beware. (And, of course, make sure you get fully hydrated in between any dry fasts you might do.)

4. Fast While You Sleep

Ramadan-style probably isn’t ideal from a pure physiological standpoint. The length (16 hours) is great, but the eating schedule is not. Those who observe Ramadan fasting ritual often wake up before sunrise to fit in food. They may stay up late to eat more. They go to sleep in a well-fed state, never quite taking advantage of the 8 hours of “free” fasting time sleep usually provides (and, of course, that’s not what their fasting practice is about). For a health-motivated dry fast, on the other hand, you should take advantage of it.

5. Take Weather Into Account

Hot, humid weather will generally cause the most water loss. Cold, dry weather will cause the least. Adjust your dry fasting duration accordingly.

6. Listen To Your Body

I’ve said this a million times, but it’s especially worth saying here. If you’re not feeling well during the dry fast, listen to your instinct rather than your agenda. (And don’t begin a dry fast when you’re ill. That should go without saying.) This is an optional tool. There are hundreds of other ways to serve your health and well-being. Don’t lose the forest through the trees because you’re drawn to a practice that feels more radical. Approach it smartly, but let your body’s intuition be the final arbiter.

That’s it for me. I haven’t done any dry fasting, not on purpose at least, and I’m not particularly interested in it for myself, but I am interested in your experiences. Do any of you do dry fasting? What have you noticed? What do you recommend?

As always, if you have any questions, direct them down below. Thanks for reading!

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References:

Mascioli SR, Bantle JP, Freier EF, Hoogwerf BJ. Artifactual elevation of serum creatinine level due to fasting. Arch Intern Med. 1984;144(8):1575-6.

Fernando HA, Zibellini J, Harris RA, Seimon RV, Sainsbury A. Effect of Ramadan Fasting on Weight and Body Composition in Healthy Non-Athlete Adults: A Systematic Review and Meta-Analysis. Nutrients. 2019;11(2)

Fahrial syam A, Suryani sobur C, Abdullah M, Makmun D. Ramadan Fasting Decreases Body Fat but Not Protein Mass. Int J Endocrinol Metab. 2016;14(1):e29687.

Aliasghari F, Izadi A, Gargari BP, Ebrahimi S. The Effects of Ramadan Fasting on Body Composition, Blood Pressure, Glucose Metabolism, and Markers of Inflammation in NAFLD Patients: An Observational Trial. J Am Coll Nutr. 2017;36(8):640-645.

Unalacak M, Kara IH, Baltaci D, Erdem O, Bucaktepe PG. Effects of Ramadan fasting on biochemical and hematological parameters and cytokines in healthy and obese individuals. Metab Syndr Relat Disord. 2011;9(2):157-61.

Saleh SA, El-kemery TA, Farrag KA, et al. Ramadan fasting: relation to atherogenic risk among obese Muslims. J Egypt Public Health Assoc. 2004;79(5-6):461-83.

Gueldich H, Zghal F, Borji R, Chtourou H, Sahli S, Rebai H. The effects of Ramadan intermittent fasting on the underlying mechanisms of force production capacity during maximal isometric voluntary contraction. Chronobiol Int. 2019;36(5):698-708.

Shephard RJ. Ramadan and sport: minimizing effects upon the observant athlete. Sports Med. 2013;43(12):1217-41.

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Top 10 Fasting Mistakes and How to Avoid Them

Folks, you know I’m a long-time believer in intermittent fasting for longevity, autophagy, mental clarity, fitness performance, metabolic health, and more. I’m excited that Dr. Jason Fung has stopped by the blog today to share a bit about common fasting mistakes. Enjoy!

So, you’ve decided to add some fasting to your lifestyle. Excellent. No matter how much you have (or haven’t) read on the topic, you’re likely to find aspects of fasting to be challenging or even frustrating. It can be hard to stay on track when you’re feeling hungry, irritable and not really noticing any changes.

It’ll become tremendously easier once you begin to experience the health benefits of fasting, but we all know it takes a little while for that to happen. Benefits like mental clarity and improved energy will show up sooner than significant weight loss. Plus, the benefits you experience will depend on what kind of fast you’re doing and how well you stick to it.

But if you’re making fasting mistakes, you might never accomplish the benefits you were hoping for. . Before you throw in the towel, I want to help you identify some possible fasting pitfalls you might not be aware of and also help you avoid them. Plus, don’t miss the Number One reason fasts fail, shared at the end of this article.

1. You’re Snacking or “Grazing”

Look, the entire purpose of a fast is to contain your eating within certain windows of time. Snacking or “grazing” all day long is basically the opposite of fasting, so stop thinking that you can get away with it. Fasting is “on” or “off”—there is no gray area. Even having “just a bite,” no matter how healthy or how little, will almost invariably kick your body out of fasting mode and will interfere with the healing process responsible for fasting’s many benefits. It also creates a situation where your body is producing insulin all day long. Bad idea.

Avoid grazing by putting snacks and food out of sight. The phrase “out of sight, out of mind” really applies here. You’ll be amazed how much easier it is to bypass snacking when the food isn’t sitting right in front of you. If you snack out of habit, get creative and find new, non-food based habits. If your snacking comes from genuine hunger, you may need to re-evaluate the meals you eat during your eating window. Make sure you’re getting enough healthy, unsaturated fats with each meal as these will keep you satiated for longer.

2. You Aren’t Drinking Enough Water

This is not only a common fasting mistake, but a mistake most people make no matter what their diet is. Drinking a minimum of eight glasses of water daily is essential to staying hydrated and healthy. Some signs that you aren’t drinking enough water include dizziness and lightheadedness, feeling tired, or constipation.

Even worse, when you don’t drink enough water, your brain may try to trick you into thinking that you’re hungry, so you get the vitamins and minerals you’re lacking. Minerals like potassium and magnesium are essential to your brain health. So don’t be surprised next time you feel hungry but find that drinking a glass of water makes the appetite disappear. Various kinds of tea are also a satisfying way to hydrate, or try some bone broth if you’re truly struggling.

3. You Aren’t Consuming Enough Salts

Speaking of vitamins and minerals, appropriate salt intake is vital to your health. Now, when I say “salt,” I’m not talking about the kind you put in a shaker. I’m talking about electrolytes, which are essential to your diet. Sodium (Na), which is also commonly known as table salt, is one of these electrolytes, along with potassium (K), magnesium (Mg), calcium (Ca), and chloride (Cl).

How can you tell if you’re low on electrolytes? Some symptoms of electrolyte deficiency are anxiety, irritability, trouble sleeping, muscle spasms, fatigue, digestive issues, and dizziness. If these are the kinds of symptoms you experience during your fast, lack of electrolytes could be the answer. Try taking some pink Himalayan rock salt and placing it under your tongue to dissolve. You can also try drinking some pickle juice — just make sure it’s from high-quality natural pickles and not the kind made with sugar.

4. You’re Eating Right Before You Go To Sleep

Your body needs time to digest all the food from your last meal before you go to sleep. If you’ve scheduled your eating window to happen right before bedtime, your body will be taking all the time you’ve allotted to rest to digest instead. That takes energy, and instead of waking up feeling restored and ready to take on the day, you’ll just feel tired.

When you’re following a fasting plan, a seven-hour window is an ideal amount of time to leave between your last meal and when you go to sleep. Even three or four hours is enough to make a difference. Unfortunately, with crazy work schedules and early mornings, a lot of people aren’t able to stick to that three- or four-hour window. It’s more like get home, eat dinner, and go straight to bed. If this is you, the next best thing is to eat a light meal, like salad, and avoid a meal filled with carbohydrates and protein.

5. You’re Eating Too Much of Some Food Groups

When we cut certain foods from our diet, especially carbs, it’s easy to rely on other food groups, like nuts and dairy. They’re readily available and a staple of most diets.

Nuts are a low-carb, healthy fat option, but only in small amounts. They’re great to add to fruit or veggie salads, and they’re easy to grab a handful of when you need a quick snack. But those quick snacks can add up, especially on top of eating full meals. Nuts are high in good fat, low in carbs, and are a good source of protein, but too much protein can be detrimental to your fast. Excess protein that your body doesn’t need is converted to glucose and stored as fat. If you’re fasting to lose weight, this is the exact opposite of what you want.

Dairy, the other easy food group that too many people defect to, can cause inflammation, upset stomach, bloating, gas, and other kinds of discomfort. If this is a pattern you’ve noticed with your own health and eating habits, try cutting out dairy for a few weeks and see if these symptoms improve. If you haven’t noticed these symptoms, be more mindful of your eating habits and track how you feel after eating dairy.

6. You Aren’t Eating Enough of Certain Food Groups

As easy as it is to eat too much of one food group, it’s equally easy to not get enough of another. Just because you can eat “whatever” you want during your eating window doesn’t mean you should. Empty calories and junk food are momentarily satisfying, but they don’t fuel your body. Eating the right foods provides your body with the nutrients it needs to thrive throughout the day; these foods will also keep you feeling fuller, longer.

Vegetables are one of the best food groups to keep you nourished and thriving. They’re low calorie and they provide different vitamins and minerals like potassium, fiber, folate, vitamin A, and vitamin C. Fruits are also healthy, but don’t overdo it, as most are high in sugar. Fruit juices typically have added sugar as well. Naturally flavored drinks and teas are the healthiest option. Nuts are high in fat and a good source of protein, as are eggs. Refined carbohydrates and sugars are highly unnecessary for your body and if you’re going to include them in your meals, there should be very little.

7. You’re Pushing Your Body Too Hard

Did you dive off the deep end and go from zero fasting to attempting 24-hr fasts every other day? Back up and take a more moderate approach first. Don’t expect fasting to be easy right away. Not only will your body need time to adjust, but your mind will, too. If you’ve been accustomed to three square meals a day, plus snacks and calorie-filled drinks, your body has gotten used to this routine.

Your body needs time to adapt. First it burns through stored sugar and then it will start burning body fat for energy. Start slow and get a feeling for this new practice. You can start with a twelve-hour fasting period and twelve-hour eating window. When eight hours of that fast are during your sleeping hours, this window is relatively easy. Once you’ve become accustomed to this schedule, you can reduce your eating window to ten hours. Continue decreasing your eating window by two hours every one to two weeks, until you’ve hit the fasting period you want.

8. You Have the Wrong Mindset

Fasting provides your body with everything it needs to thrive, but without the right mindset, you’re bound to fail. Focusing on the negative, like not being allowed to eat certain foods or at certain times, will easily spiral into other negative self-talk. The harder you are on yourself, the more difficult it is to achieve success.

Rather than thinking about how hard the fast is, focus on the positive that will come out of it. Fasting allows your body to heal. Fasting can help you lose weight. You’ll feel more energized and have a clearer mind. Whatever the reason you’ve chosen to fast, focus on that. Fasting with a friend, family member, partner, or online community is another way to hold yourself accountable and can be very helpful.

9. You’re Too Stressed

When you’re stressed, your body releases a hormone called cortisol. Cortisol is problematic when fasting because it can prompt your body to break down muscle tissue instead of fat. When fasting, your body should tap into stored body fat and preserve your healthy muscle tissue.

If you’re stressed on occasion, this shouldn’t cause much of a problem. But if you’re chronically stressed, that constant release of cortisol can lead to a breakdown of muscle tissue.

Not sure if you’re stressed? Here are some symptoms:

  • Teeth grinding
  • Muscle tension
  • Headaches
  • Apathy
  • Anger
  • Digestive problems
  • Fatigue
  • Trouble concentrating

Alleviate stress with deep breathing, positive visualization, an epsom salt bath, and stress-relieving teas. If you can, take some time off from work. If you’re an outdoorsy person, relax in nature.

10. You’re Inactive

Being inactive is one of the biggest mistakes people make during their fast. If you aren’t eating, you should rest and save your energy, right? Wrong. Exercise is a great way to improve your fasting. Activity increases fat burning and boosts circulation. Going outside and getting some sunlight and fresh air can improve your mood, making you more likely to stick to your fast. Movement generally makes people feel better than sitting on the couch inside all day; being inactive makes you cold, tired, and unfocused.

Since a lot of people work sedentary jobs that tie them to a desk all day, exercise isn’t a convenient way to stay active. But taking a short walk or stretching are two easy ways to get your blood flowing throughout the day.

Fasting shouldn’t be synonymous with suffering. If you’re feeling deprived during your fast, be sure that you aren’t making any of the above fasting mistakes. Ease yourself into your fast, stick with it, and enjoy the results when they come with time.

But there’s one more—in fact, the number one reason fasts fail….

Can you guess what it is?

***Giving Into Cravings

Which is why I want to tell you about my new favorite secret weapon for staying fasted longer and with less difficulty: Pique Fasting Teas. Why tea? The combination of catechins and caffeine gives you a higher chance of experiencing tangible benefits from fasting. It suppresses hunger cravings, boosts calorie burn and supports malabsorption of unhealthy fats and sugars.

These Fasting Teas include ingredients targeted at maximizing the fasting experience:

1) Organic highest ceremonial grade matcha, which increases levels of l-theanine to calm and tide you through your fasts with ease. 2) Organic peppermint, which is a natural appetite suppressant with calming properties. 3) Proprietary blend of high catechin green Tea Crystals, which regulate the hunger hormone ghrelin and increase thermogenesis (burning fat for fuel). This helps you to stay fasted and see quicker results. 4) Additional plant ingredients including ginger and citrus peel to support digestion and enhance autophagy.

As with all of Pique’s teas, you can rest assured these are pure and Triple Toxin Screened for pesticides, heavy metals and toxic mold. For a limited time only, if you order through the Mark’s Daily Apple link, you can get up to 8% off and free shipping (U.S. only).

Thanks again to Dr. Jason Fung for today’s post. Have questions on fasting protocols or missteps? Share them below, everybody, and have a great day.

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Keto and the Menstrual Cycle: Is There Reason To Worry?

It seems every “keto for women” forum abounds with stories about menstrual cycles gone wild in the first few months of keto. Irregular cycles, breakthrough bleeding, and periods lasting much longer than normal are common complaints. Sometimes these stories are cited as evidence that keto isn’t good for women, at least not premenopausal women, and that we need carbs for healthy hormones. Yet, many women don’t notice any changes in their menstrual cycles at all, while others report improvement in PMS symptoms and cycle regularity from the get-go.

What gives? Why do some women’s cycles apparently become wacky when they start keto, while others feel like keto is the key to period bliss? Can keto “mess up” the menstrual cycle?

We know that diet—what and how much we eat—can profoundly affect our hormones. This is true for both women and men. One of the reasons people are so excited about ketogenic diets is specifically because keto shows promise for helping to regulate hormones and improve cellular sensitivity to hormones such as insulin and leptin.

At the same time, women’s hormones are especially sensitive not only to dietary changes but also to downstream effects such as body fat loss. Furthermore, one of the ways women’s bodies respond to stressors is by turning down the dial on our reproductive systems. It’s reasonable to hypothesize, then, that women might have a tougher time adapting to or sustaining a ketogenic diet. Keto can be stressful depending on one’s approach, and that might negatively impact women’s reproductive health. But do the data actually bear that out, or is so-called “keto period” more misplaced hype than genuine fact?

Note that throughout this post, I’m going to use the term “reproductive health” to refer to all aspects of women’s menstrual cycle, reproductive hormones, and fertility. Even if you aren’t interested in reproducing right now, your body’s willingness to reproduce is an important indicator of overall health. When your reproductive health goes awry—irregular or absent periods (amenorrhea) or hormone imbalances—that’s a big red flag. Of course, post-menopausal women can also experience hormone imbalances that affect their health and quality of life (and low-carb and keto diets can be a great option for them).

Menstrual Cycle 101

Let’s briefly review what constitutes a normal, healthy menstrual cycle, understanding that everybody’s “normal” will be a little different. A typical cycle lasts from 21 to 24 days on the short end to 31 to 35 days on the long end, with 28 days being the median. Day 1 is the first day of your period and begins the follicular phase, which lasts until ovulation. Just before ovulation, levels of luteinizing hormone (LH), follicle stimulating hormone (FSH), and estradiol (a form of estrogen) spike. Next comes the luteal phase covering the approximately 14 days from ovulation to menses. LH, FSH, and estradiol drop, while progesterone rises. Estradiol bumps up again in the middle of the luteal phase. If a fertilized egg is not implanted, menstruation commences, and the whole cycles starts over again. All this is regulated by a complex communication network under the hypothalamic–pituitary–gonadal (HPG) axis, which is closely tied to the actions of the adrenal (the A in HPA axis) and thyroid glands.

Across the cycle, fluctuations in body weight are common as fluid is retained and then released along with shifts in estrogen and progesterone. Changes in blood glucose are also normal, and insulin-dependent diabetics often find that they need to adjust their dose at different times of their cycles to keep their blood sugar in check. The most common pattern is higher blood glucose readings in the pre-menstrual period (the second half of the luteal phase), and lower readings after starting your period and before ovulation. This is generally attributed to the fact that progesterone, which is highest during the luteal phase, is known to reduce insulin sensitivity. However, different women experience different patterns, which can also be affected by other factors such as oral contraceptive use.

Normal fluctuations in insulin resistance and blood glucose can mean that women get lower ketone readings at certain times of the month than others. When these occur premenstrually—and so they tend to coincide with a period of (transient) weight gain and food/carbohydrate cravings—women often feel as though they are doing something wrong. Rest assured that these variations reflect normal physiology.

The many factors that affect your cycle and the levels of your sex hormones include: other hormones, gut health and microbiome, metabolic health (e.g., insulin sensitivity), environmental toxins, stress, sleep, immune health, nutrient deficiencies, activity level and energy expenditure, and age. Each affects the others, and all (except age of course) can be affected by diet. It’s no surprise, then, that it can be extremely difficult to pin down a root cause of menstrual changes or reproductive issues.

What the Research Tells Us About Keto and Menstruation

As I said at the outset, there are lots of anecdotes, both positive and negative. In my experience, most women whose cycles seem to go crazy when they start keto find that things get back to normal—and often a better version of normal—after a few months.

First, it’s tricky to determine the effects of keto per se, since many people combine a ketogenic diet with calorie restriction (intentionally to lose weight or unintentionally due to the appetite suppressing effects of keto) and with fasting (intermittent and/or extended). Each of these can independently impact the factors listed above, lead to weight loss, and affect the menstrual cycle and reproductive health.

So, is there any evidence that keto itself causes changes to menstruation?

The scientific evidence is scant….

The one statistic you’ll see floating around the interwebs is “45% of (adolescent) females experience irregular menstrual cycles on keto.” This statistic comes from one small study of adolescent girls using a therapeutic ketogenic diet to treat epilepsy. Six of the twenty girls reported amenorrhea (loss of period) and three were diagnosed with delayed puberty. However, the ketogenic diet used for epilepsy is different and usually much stricter than an “everyday” keto diet needs to be, and epilepsy is frequently associated with menstrual dysfunction regardless of diet.

To extrapolate the findings of this study and argue that nearly half of teenage girls (or women generally) are likely to experience menstrual problems from going keto is a huge leap.

The fact is, I’m unable to find any studies done in healthy human females (or mice for that matter) demonstrating that otherwise normal menstrual cycles are disturbed by going keto.

5 Ways Keto-Related Factors *Might* Affect Your Menstrual Cycle

With the limited amount of research looking directly at keto and menstruation, let’s look first at whether there are direct effects of carbohydrate restriction or elevated ketone production on the menstrual cycle. Those are the defining characteristics of keto and what differentiates keto from other ways of eating. Then we can examine indirect effects that occur due to factors such as weight loss. These are not unique to keto, though they might be more likely on a ketogenic diet compared to other ways of eating.

Carbohydrate Restriction

There is no real body of evidence that looks at ketogenic levels of carb restriction and menstruation, but there are some clues. In this small study, functional hypothalamic amenorrhea (FHA) was associated with dietary fat restriction; women with FHA actually ate non-significantly more carbs than matched controls and nearly identical total calories. Likewise, in this small study, FHA was associated with lower fat intake but no significant difference in carb intake.

This meta-analysis looked at the effect of low-carb (not keto) diets on markers of reproductive health among overweight women. The researchers found four studies that examined effects on menstruation; all showed improved menstrual regularity and/or ovulation rates. Of six studies that looked at levels of reproductive hormones, five reported significant improvements.

Carb restriction also results in decreased insulin production. Hyperinsulinemia and insulin resistance are frequently associated with polycystic ovarian syndrome (PCOS), one of the leading causes of female infertility and a frequent cause of menstrual irregularity. There is currently a lot of interest in using keto to treat PCOS, but only one small study has so far directly tested the effectiveness of a ketogenic diet to treat PCOS, with positive results.

Ketones

No studies have looked at the direct effects of ketones on menstruation.

Weight Loss

Of course weight loss is not unique to keto, but keto can be very effective for weight loss. Some women experience rapid weight loss when first starting a keto diet. Weight loss in and of itself can impact menstruation through a variety of pathways (and, of course, keto isn’t the only way people lose weight). A key way is by reducing the hormone leptin. Leptin’s main job is to communicate energy availability to the hypothalamus—high levels of leptin tell the hypothalamus that we have enough energy on board, which also means we can reproduce. Low leptin can disrupt the menstrual cycle and is linked to hypothalamic amenorrhea.

Body fat loss can also affect estrogen levels since estrogen is both stored and produced in adipocytes (fat cells). While fat loss in the long term will decrease estrogen production, it is possible that rapid fat loss might temporarily raise estrogen levels and can also affect estrogen-progesterone balance. These transient changes in estrogen levels might underlie some of the menstrual irregularities women report.

Stress

Stress can impact the menstrual cycle in myriad ways. Cortisol acts on the hypothalamus and pituitary glands, affecting hormone levels, sleep, immune function, and gut health, to name a few. Diets can be a source of stress, both at the physiological and psychological levels. Keto has a reputation for being especially stressful because it is more restrictive than other low-carb diets, but this can be mitigated by following the Keto Reset tips for women.

Thyroid Function

Thyroid dysregulation is another common cause of menstrual irregularities, and there remains a pervasive belief that keto is bad for thyroid health. Indeed, the thyroid is sensitive to nutrient deficiencies and caloric restriction, and thyroid hormones, especially T3, do frequently decline on keto. However, as Mark has discussed in a previous post, changes in T3 levels might not be a problem, especially in the absence of other problematic symptoms. Moreover, many practitioners now use keto as a cornerstone in their treatment of thyroid disorders.

What Should I Take From These Findings?

The first takeaway: there just isn’t much direct evidence about how keto might affect your menstrual cycle, positively or negatively. We have some studies suggesting that low-carb diets improve some aspects of menstruation and reproductive health, but keto is more than just another low-carb diet. Ketones themselves have important physiological properties, such as being directly anti-inflammatory, which might positively impact women’s reproductive health.

Second, the ways that keto is likely to (negatively) affect menstruation aren’t unique to keto, they’re common to any diet: hormone shifts mediated by energy balance, stress, and weight loss.

Furthermore, since keto is so often combined with caloric restriction, time-restricted eating, and fasting, even the anecdotal evidence might not be able to tell us all that much. If a woman is eating ketogenically, in a big caloric deficit, and doing OMAD (one meal a day), and her leptin plummets, how are we to know what really caused it? We don’t have good evidence that otherwise healthy women start a well-executed ketogenic diet and end up messing up their menstrual cycles.

That said, women do need to be cognizant of the sum total of the signals they are sending their bodies when it comes to energy availability and stress. A lot of women come to the keto diet with a history of adrenal, thyroid, metabolic, and reproductive issues. It’s important that they’re extra careful about how they approach keto. Done correctly, it might be just what the doctor ordered. I encourage any woman who’s dealing with other hormonal issues to work with a medical practitioner to tailor a keto diet to her unique needs.

But I’m Telling You, Keto Made My Period Go Haywire!

Ok, I believe you, really! But changes do not necessarily equal dysfunction. It is normal to experience hormone fluctuations when you make a massive—or even a relatively small but important—shift in your nutrition. Sometimes those fluctuations are unpleasant or unwanted, such as a period that lasts 14 days or one that arrives a week before you planned while you’re on vacation. However, that doesn’t make them bad from a health perspective. We need to respect that our bodies are dynamic systems. Changing the input will invariably change the output, and the system might need a few months to adapt to a new normal.

If your cycle goes wonky but you’re otherwise feeling good, give it a few months to sort itself out. If after a few months it’s still all over the place (or definitely if you’re having other disruptive symptoms), enlist help. In the meantime, check to make sure you’re not short-changing yourself nutritionally or calorically. Scale back on fasting efforts, and consider shifting more toward a traditional Primal way of eating.

At the end of the day, if you go keto and experience negative effects, stop. Keto is super hyped right now, but if your body is sending you clear signals that keto is not a good approach for you at this time, don’t do it. You can always try again later. It might be that your first attempt at keto didn’t work, but with a few adjustments and some experimentation over time you can find a version of keto that works for you.

Thanks for reading, everyone. Do you have comments, questions, or feedback? Let me know below.

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References:

Comninos AN, Jayasena CN, Dhillo WS. The relationship between gut and adipose hormones, and reproduction. Human Reproduction Update 2014; 20(2): 153–174.

Fontana R, Della Torre S. The Deep Correlation between Energy Metabolism and Reproduction: A View on the Effects of Nutrition for Women Fertility. Nutrients. 2016;8(2):87.

Klok MD, Jakobsdottir S, Drent ML. The role of leptin and ghrelin in the regulation of food intake and body weight in humans: a review. Obesity Reviews 2007;8(1):21-34.

Meczekalski B, Katulski K, Czyzyk A, Podfigurna-Stopa A, Maciejewska-Jeske M. Functional hypothalamic amenorrhea and its influence on women’s health. J Endocrinol Invest. 2014;37(11):1049–1056.  

Tena-Sempere M. Roles of Ghrelin and Leptin in the Control of Reproductive Function. Neuroendocrinology 2007;86:229-241.

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What Breaks a Fast: Supplement Edition

Last week, I explored the impact of all the various foods, beverages, and food-like substances people consume while fasting—and hoping to maintain a functionally fasted state. Does MCT oil break the fast? What about coffee, tea, or bone broth?

There were more than a dozen, and I even did a follow-up. Today I’m going to discuss whether commonly-consumed supplements break the fast.

Let’s go:

Fish Oil

Fish oil is pure fat. If you’re taking the average supplemental dose of 1-2 grams of fish oil, it’s not a problem. That’s not even a teaspoon. It’s about 9-18 calories.

You may burn slightly less fat than you would otherwise, but in the grand scheme of things, a few grams of fish oil won’t break the fast.

Cod Liver Oil

Cod liver oil is fish oil with extra vitamin D and vitamin A. As long as you keep the doses low enough, cod liver oil won’t break the fast.

Multivitamin/Multimineral

Multivitamins do not break a fast. They are usually non-caloric. However, not all of their components will be absorbed very well on an empty stomach, so keep that in mind.

If you’re still not on board, note that in the older studies with really overweight people who fasted for upwards of a year straight, they usually supplemented with a multivitamin.

Food-Based Multivitamin

A popular one I’ve seen around—Alive, made from kale and raspberries—has just 2 grams of carbs per dosing. It’s not ideal, but it’s not a deal breaker—or a fast-breaker.

Gummy Vitamins

Gummy vitamins have the potential to be about 5-6 grams of sugar, a gram of protein (from gelatin), and a gram of fat (if including omega-3s) per serving, so they’d arguably break the fast. Plus, they taste like candy and are likely to stimulate cravings and make fasting harder.

Gummy vitamins break the fast.

Potassium

Potassium is non-caloric and does not break the fast. In fact, it can help you handle the fast better by replenishing electrolytes.

Potassium doesn’t break the fast.

Creatine

Creatine contains no calories and has no effect on insulin secretion (or glucose in the absence of calories).

Creatine does not break the fast.

Protein Powder

Protein powder provokes an insulin response, which opposes autophagy, which means you’re breaking your fast. Plus, protein powder contains calories.

I’m going to say “yes, protein powder breaks the fast.

Collagen

If you’re strict and technical, then yes, collagen breaks a fast. There’s evidence that glycine—the most prominent amino acid in collagen—can inhibit autophagy, but it was a convoluted animal study where inhibiting autophagy with large doses of glycine after brain injury actually improved outcomes. It probably doesn’t apply to someone adding a scoop of collagen to their coffee. Besides, even if it slightly reduces autophagy, a little collagen won’t negatively impact ketosis, fat-burning, or energy intake.

I’m going to say “technically yes,” but “realistically no, collagen doesn’t break the fast.” Avoid if your main focus is autophagy, however.

Branch Chain Amino Acids (BCAAs)

BCAAs trigger an insulin response and thus stop autophagy…and the fast. That said, many proponents of fasted training recommend using BCAAs before a workout to help preserve muscle and improve the post-workout anabolic response.

I’m going to say “yes, BCAAs break the fast.”

Vitamin D

Vitamin D is fat soluble and thus comes packaged in an oil carrier, but the dosage is so small that it won’t affect your fast.

Unless you find that 1/8 teaspoon of olive oil ruins your fast, vitamin D won’t break a fast.

Probiotics

Probiotics contain no calories and will not break a fast. However, they are best absorbed in the presence of food—the food protects them as they travel through the digestive system, and most probiotics occur naturally in food—so taking them during a fast is probably, mostly useless.

Probiotics don’t break a fast, but why take them during one?

Prebiotics

Pure prebiotics will not break a fast, as they contain no digestible carbohydrates. Prebiotic-enriched foods will break a fast, as they do contain calories.

Adaptogens

Adaptogens are compounds, usually herbs or herb derivatives, that modulate your stress response. They improve your ability to tolerate and respond to stressful situations; they don’t blindly inhibit the stress response if the stress response is warranted. They keep you honest and counter unnecessary stress responses. They contain no calories, unless you’re chowing down on a big hunk of maca or ashwagandha root. In fact, most adaptogens have traditionally been consumed in tea form, extracting the active compounds and leaving behind any calories. Have at ’em.

Adaptogens do not break the fast.

Mushroom Extracts

Medicinal mushroom extracts come from mushrooms, which are technically food. But the amounts you take are so low—usually no more than a teaspoon—that they won’t impact your fast or provide any significant amount of caloric energy. Four Sigmatic has those “mushroom coffee” blends you add to hot water. They can get up to about 30 calories per serving, but even that’s going to let you maintain most of the fasting benefits.

Mushroom extracts don’t break the fast.

Melatonin

I used to keep the old Trader Joe’s melatonin on hand because it was half a milligram, whereas most other melatonin supplements are in the 3-5 mg range. It was also sweet, tasting like those white Valentine’s Day mint hearts you used to get back in the day. I haven’t come across any sweetened melatonin supplements since Trader Joe’s phased those out, but that’s the only thing I’d worry about on a fast.

Melatonin does not break a fast.

Final Note: Most supplements are okay to take on a fast, though the lack of food may make absorption more difficult. If you have any other questions about supplements on a fast, drop them down below. Thanks for reading, everybody.

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Dear Mark: What Breaks a Fast Followup

For today’s edition of Dear Mark, I’m answering a round of questions drawn from the comment section of the “What Breaks a Fast” post. You folks had tons of follow-up questions about whether other types of foods or compounds break a fast. Does a teaspoon of honey? Does elevated insulin from BCAAs? Does coconut milk? Does pure prebiotic fiber? What about longer fasts—are they recommended? And how about unsweetened cocoa powder? What explains my ability to predict your questions? Do sausages break a fast? Does liquor? How should you exercise?

Let’s dig right in:

Hey, what about honey? 1 tsp in morning tea?

A teaspoon or less of honey is fine and won’t negate the benefits of fasting. I alternate between doing collagen coffee and coffee with cream and teaspoon of sugar (which was my typical morning coffee for over a decade). No reasonable person should fear a teaspoon of sugar or honey.

For what it’s worth, honey isn’t “just” sugar. It elicits a more beneficial (or less negative) metabolic response than other forms of sugar.

I’m shocked about the BCAA. I used to fast and take BCAA’s (yes, to continue dynamic exercise). I used to find it extremely difficult to fast compared to now when I fast without taking them. Does that mean that the insulin response made fastic more difficult?

It’s possible. Insulin impairs lipolysis—the release of stored body fat into circulation for energy usage—and the success of fasting depends on lipolysis. Without lipolysis, you can’t access all that stored energy.

Thank you very much for this info!! I am a butter-coffee-for-breakfast drinker, and I always worry about the ingredients breaking a fast. Could you please comment on coconut milk (in the can)? I love putting that in my coffee/breakfast.
Thanks.

Coconut milk is a less concentrated source of medium chain triglycerides, or MCTs (as in MCT oil). MCTs convert directly to ketones, making MCT oil and to a lesser extent coconut oil or coconut milk a potential “boost” for fasting. Still, energy is energy, and any energy you take in is energy you won’t be pulling from your body.

I find MCTs and coconut to be more useful when someone is just getting the hang of fasting or ketosis—as a nice boost to get things moving in the right direction.

Keep your coconut milk under a tablespoon and you’ll be fine.

Does prebiotic (resistant starch) fiber break a fast? Acacia senegal or potato starch? Thanks!

No. If you’re worried, test your postprandial blood sugar after eating the fiber.

Great input Mark as someone 3days into a 7day water fast with electrolytes of course what’s your view on longer fasts.

Check out the post I wrote on long fasts. Potentially beneficial but the risks accumulate the longer you go. You just have to be even more careful and methodical.

How about unsweetened cocoa?

A tablespoon runs just over 12 calories (depending on the brand; some cocoa powders contain more fat and thus more calories), with around a gram of net carbs and a gram of fat. Also a nice source of potassium and magnesium, along with a ton of polyphenols which can have fasting-mimicking effects on their own.

Eating enough unsweetened cocoa powder to knock you out of your fast would be incredibly repulsive. Probably impossible.

Cocoa is definitely a nice addition.

Okay it’s almost creepy the way Sisson answers my questions before I even ask them! I was wondering about this yesterday and then this post popped up in my inbox.

How does he do that…? ?

Kraft-Heinz has a strong relationship with Google and Amazon, and the Kraft acquisition gave me access to Alexa/Google Home datasets and the ability to predict what my readers are wondering about.

Just kidding, though it’s scarily not out of the realm of possibility anymore.

What about a small snack of paleo sausages, smoked or dried? So meat and fat (beef, pork or lamb), and some spices. Maybe 100g worth.

Well, that’s a legit snack bordering on a small meal. That will break the fast, but it’s not all for naught. There is the whole “fasting-mimicking diet,” where you eating very few calories for several days out of the week and retain many if not most of the benefits of full-on fasting.

Let’s just say if you ate a small snack of paleo sausages on your “fasting” days, you’d still be way ahead of 99% of people.

But do try a full-on fast at least once. You might surprise yourself.

Great post! What about alcohol? Specifically, a shot or 2 of liquor. I would assume beer and wine would break a fast, but what about whiskey or tequila?

When alcohol enters the system, utilization of all other energy sources is suspended until the alcohol is burned. Back in 1999, researchers did a study where they gave fasting adult men the equivalent of a couple shots of liquor. They stopped releasing stored body fat, stopped burning body fat, and began burning way more acetate (a product of ethanol metabolism). They didn’t exactly “break” the fast, but all the metabolic trajectories we love about fasting took a big pause.

Good morning Mark,
How does one exercise in the morning while fasting? When to eat?

You can exercise any way you like, but I change how I train based on when I’m going to break the fast with food.

If I’m going to break the fast with a meal right after, I train any way I like. I’ll do sprints, HIIT, weights, anything.

If I’m going to keep fasting after the workout, I like to stick to strength training and low-intensity movement (walking, hiking, standup paddling). The strength training is essential during a fast because it’s an anabolic signal to your muscles—move it or lose it. Simply lifting heavy things during a fast can stave off muscle loss.

That’s it for today, folks. Stay tuned later this week for “What Breaks a Fast: Supplements Edition.”

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The Definitive Guide To What Breaks a Fast

One of the most common questions I get is “Does [x] break a fast?”

What they’re really inquiring about is: “Does this interfere with, negate, or nullify the benefits of fasting?”

These benefits include:

Ketosis: Fasting is the quickest way to get into ketosis, an metabolic state characterized by increasing fat burning, fat adaptation, and—in some people—improved cognitive function.

Fat Loss: When you’re fasting, you’re not eating, and not eating is the best way to force your body to burn the fat it already possesses. Fasting also means no additional calories are coming in, and many people find that fasting is a great way to control their calorie intake.

Autophagy: Autophagy, or “self-eating,” is the process by which our cells prune damaged components, maintain proper function, and keep aging at bay. Fasting triggers autophagy. Breaking the fast will stop autophagy.

Let’s go through the most popular queries one by one and figure out how each one affects an intermittent fast.

Common Drinks

Coffee

Depends on who you ask. Some say the fact that coffee triggers a metabolic response means it breaks the fast. I say that coffee increases fat mobilization and burning, independently triggers autophagy (something we’re looking for when we fast), and makes it easier to stave off hunger. For my full treatment, check out this post on coffee and fasting.

I’m going to say “no.”

Tea

Tea contains no calories, improves metabolic health, and can aid fat burning. All signs point to it being great during a fast. Of course, if you had a tablespoon of sugar and a half cup of milk, you’re breaking the fast. But tea itself is a great addition.

I’m going to say “no.”

Yerba Mate

Yerba mate is essentially non-caloric, like tea or black coffee. It also has beneficial effects on glucose tolerance, which is a big plus.

I’m going to say “no.”

Bone Broth

I covered this in full a few months ago. Go read that post. In short, a bit is probably okay. Just keep in mind that the more gelatinous your broth is, the more collagen protein it will contain and the greater its potential to inhibit autophagy. This isn’t established in humans yet (see the collagen section below), but it’s worth considering. A nice salty broth has gotten many a faster through a tough fast, especially if they’re still learning the ropes and need some electrolytes.

I’m going to say “technically yes” but “realistically no.”

Lemon Water

A tablespoon of fresh squeezed lemon juice has a couple calories and a decent amount of potassium. Combined with salt, lemon water is actually a nice way to hydrate during a fast without breaking it.

I’m going to say “no.”

Diet Soda

Diet soda may mess with your gut. It’s linked to weight issues, though not conclusively and certainly not in a causative manner; it’s just as likely that the relationship can be explained by overweight and unhealthy people using diet sodas in a bid to lose weight. I don’t like them myself, and I’ve witnessed people fail to ever kick the sweet tooth as long as they drank diet sodas. But many people find they do improve dietary adherence and do improve fasting tolerance. If that’s the case, they are very pro-fasting.

I’m going to say “no.”

Juice

A juice fast isn’t really a fast. You’re consuming fewer calories than you might eating normal food, but you’re still consuming a good number of calories—most of them carbohydrate, no less.

I’m going to say “yes” unless you’re specifically engaging in “juice fasting,” in which case it’s still not fasting despite what you call it.

Common Drink Additions/Condiments

Cream (Unsweetened)

Technically, as a source of calories, cream breaks a fast. But it doesn’t provoke an insulin response when consumed in isolation, it doesn’t impact ketosis, and many people find it makes sticking to the fast easier.

I’m going to say “technically yes, but realistically no—just keep it to a couple teaspoons or less.”

Almond Milk

It depends on the almond milk. A full cup of the standard sugar-free almond milk has just 36 calories, about a gram of carbs, 2 grams of fat, and a gram of protein. That’s almost nothing. You could probably get away with a quarter or third cup and have minimal impact on your fast, but why not just drink some water or coffee?

I’m going to say “technically yes,” but you can get away with a little bit.

Butter

Like cream, butter doesn’t provoke an insulin response in isolation. It’s more calorically dense than cream, though, so watch how much you eat.

I’m going to say “technically yes, but realistically no as long as you’re not using more than a teaspoon.”

MCT Oil/Coconut Oil

MCT oil is pure fat and thus calorically dense, but it has three benefits going for it. First, it doesn’t provoke an insulin response in isolation. Two, it increases energy expenditure. Three, it converts directly to ketones. People new to fasting can often speed up the fat adaptation process by incorporating a little MCT oil. Coconut oil is the main source of MCT oil, so it’ll have similar effects, though not as pronounced.

I’m going to say “technically yes, but realistically no—and it may even enhance your fasting experience when consumed in moderation.”

Cinnamon

I don’t advise eating cinnamon alone, dry, and isolated. It’s a terrible and potentially deadly idea. But in some coffee or tea during a fast? Sure. It can even improve insulin sensitivity.

I’m going to say “no.”

Salt

Salt does not break a fast. Actually, adding a pinch or two of salt to your water during a fast can increase your tolerance of the fasting process and improve hydration status.

I’m going to say “no.”

Non-caloric Sweeteners—First Natural, Then Artificial

Stevia

Stevia contains no calories and has no effect on insulin secretion (if anything, it increases insulin sensitivity). However, it’s often used to sweeten foods that do contain calories, so be mindful of how you’re using it.

I’m going to say “no.”

Monk Fruit

For a good overview of monk fruit, read this. Suffice it to say, monk fruit is similar to stevia in that it’s a non-caloric, naturally-occurring sweetener with unique health effects. It will not break your fast.

I’m going to say “no.”

Swerve

Swerve is a sweetener that blends erythritol (a sugar alcohol) and oligosaccharides (a prebiotic fiber that tastes kinda sweet) with natural flavors. Erythritol has no effect on insulin or blood glucose (you just pee it out mostly). I couldn’t find any studies on oligosaccharides during a fast, but as humans cannot by definition digest them, they shouldn’t affect the course of a fast.

I’m going to say “no.”

Xylitol

See the gum section above. Stick to reasonable amounts.

I’m going to say “no.”

Sucralose (a.k.a. Splenda)

Sucralose does not provoke an insulin response or increase blood glucose—great news for fasters who want to use it—but it does seem to impair whole body insulin sensitivity. That’s bad for everyone.

I’m going to say “no,” but there are other downsides.

Aspartame

Those same studies on monk fruit and stevia also tested aspartame, finding similar results. Aspartame does not provoke an insulin or glucose response. I’m no fan of the stuff, but I don’t see any evidence that it will break a fast.

I’m going to say “no.”

Supplementary Powders, Oils, Etc.

CBD Oil

Assuming you’re doing the kind of hemp oil that comes in droppers and not the kind that you pour from a culinary oil bottle, the caloric content can’t possibly impact your fast. There are no studies examining the metabolic effects of CBD in the fasted state, but I don’t see any reason why it would impact ketosis, autophagy, or fat-burning—and without psychoactive THC involved, you won’t be getting the munchies.

I’m going to say “no.”

Protein Powder

Protein powder provokes an insulin response, which opposes autophagy, which means you’re breaking your fast. Plus, protein powder contains calories.

I’m going to say “yes.”

Collagen

If you’re strict and technical, then yes, collagen breaks a fast. There’s evidence that glycine—the most prominent amino acid in collagen—can inhibit autophagy, but it was a convoluted animal study where inhibiting autophagy with large doses of glycine after brain injury actually improved outcomes. It probably doesn’t apply to someone adding a scoop of collagen to their coffee. Besides, even if it slightly reduces autophagy, a little collagen won’t negatively impact ketosis, fat-burning, or energy intake.

I’m going to say “technically yes,” but “realistically no.” Avoid if your main focus is autophagy, though.

Branch Chain Amino Acids (BCAAs)

BCAAs trigger an insulin response and thus stop autophagy and the fast. That said, many proponents of fasted training recommend using BCAAs before a workout to help preserve muscle and improve the post-workout anabolic response.

I’m going to say “yes.”

Apple Cider Vinegar

Apple cider vinegar is made by double fermenting the sugars present in apple juice. First, yeast convert the sugars to alcohol. Next, the alcohol converts to acetic acid. The result is a liquid that’s virtually calorie-free. Studies showing that consuming vinegar lowers the blood glucose response to a subsequent meal aren’t really relevant if you’re fasting, but they don’t hurt.

I’m going to say “no.”

Electrolyte Powder/Tabs

Electrolyte powders/tabs used to come festooned with sucrose, making them decidedly anti-fasting. These days, most of them are sweetened with stevia or some other natural non-caloric sweetener. Even the ones that have a little bit of sugar (1-2 g) are probably okay to consume without much negative effect. Best of all, electrolytes can really help you tolerate a fast.

I’m going to say “no.”

Breath-Freshening Items

Gum

If we’re talking sugar-rich gum, the answer is yes. Those definitely break a fast. If we’re talking xylitol gum, the answer is more mixed. In healthy individuals, 30 grams of pure xylitol triggers a small but significant rise in glucose and insulin. That might sound scary to a prospective IFer, but most people aren’t chewing gum made with 30 grams of xylitol. The average piece of xylitol gum barely weighs a gram.

I’m going to say “no,” unless you’re chewing gum made with real sugar or you’re throwing back 30 pieces of xylitol gum in a sitting.

Toothpaste

I always consume my toothpaste (around a tablespoon of the good stuff per brushing) and I’ve never had it knock me out of ketosis, autophagy, or in any way shape or form break my fast. I’m kidding. I don’t consume my toothpaste, but brushing your teeth doesn’t break a fast.

I’m going to say “no.” Don’t eat it though.

Mouthwash

Pretty much the same as toothpaste. Look for a brand that doesn’t contain sugar or one of the artificial sweeteners above that trips insulin. As the instructions (and common sense) suggest, don’t drink it.

That’s it, folks. If you have additional questions about what does or doesn’t break a fast, leave them down below. Thanks for reading, and I hope you found the post helpful. Forward it on if you did.

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References:

Hansson P, Holven KB, Øyri LKL, et al. Meals with Similar Fat Content from Different Dairy Products Induce Different Postprandial Triglyceride Responses in Healthy Adults: A Randomized Controlled Cross-Over Trial. J Nutr. 2019;149(3):422-431.

Anton SD, Martin CK, Han H, et al. Effects of stevia, aspartame, and sucrose on food intake, satiety, and postprandial glucose and insulin levels. Appetite. 2010;55(1):37-43.

Ili? V, Vukmirovi? S, Stilinovi? N, ?apo I, Arsenovi? M, Milijaševi? B. Insight into anti-diabetic effect of low dose of stevioside. Biomed Pharmacother. 2017;90:216-221.

Noda K, Nakayama K, Oku T. Serum glucose and insulin levels and erythritol balance after oral administration of erythritol in healthy subjects. Eur J Clin Nutr. 1994;48(4):286-92.

Müller-hess R, Geser CA, Bonjour JP, Jéquier E, Felber JP. Effects of oral xylitol administration on carbohydrate and lipid metabolism in normal subjects. Infusionsther Klin Ernahr. 1975;2(4):247-52.

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Dear Mark: Antibiotic Recovery, Sprinting on Keto, Preparing for Bad Sleep

For today’s edition of Dear Mark, I’m answering three questions. First up, what can a person do to help their gut recover its barrier function after too many antibiotics? Are there any foods, supplements, or dietary strategies? Second, what can explain rapid fatigue during sprint sessions on a keto diet? Is this simply part of the deal, or are there modifications you can make? And finally, what do I do when I know I’m going to get a bad night’s sleep?

Let’s go:

Mark – any idea how to cure leaky gut caused by overuse of antibiotics. Tried raw dairy for a month to no avail.

First of all, check out my post on leaky gut. Read through it and follow my suggestions for preventing and treating intestinal permeability. It’s a great place to start.

Then, let’s look at some other interventions that have been shown to improve recovery from antibiotic therapy. While most of the studies referenced don’t explicitly describe antibiotic-induced leaky gut, anything that improves gut function and restores healthy gut bacteria will also normalize leaky gut—since it’s the eradication of native gut bacteria that causes antibiotic-induced leaky gut.

Fermented dairy. You tried raw dairy. What about fermented dairy? While raw dairy has its merits, it’s fermented dairy that just works for recovery from antibiotics. Yogurt is a good option to try, although the evidence is a bit inconsistent. Kefir is probably better; it’s been shown to improve patients’ tolerance to triple antibiotic therapy during treatment for H. pylori infection. This is even worth consuming during antibiotic therapy, as many of the probiotic bacteria found in fermented dairy show resistance to common antibiotics.

Fermented vegetables like sauerkraut are also must-eats. The fermented cabbage contains ample amounts of L. plantarum, a bacteria strain that’s been shown to prevent antibiotic-related diarrhea in piglets (another omnivorous mammal). Good options exist in stores (check the refrigerated section; shelf-stable pickles and kraut aren’t lactofermented), and even more are available in farmer’s markets, but the best way to get the most bacteria-rich vegetable ferments is to make your own.

Supplemental probiotics are fantastic here, too: large doses of the desired microorganisms delivered directly to your gut. Some of the strains used in Primal Probiotics, like B. clausii and S. boulardii, have been shown to be effective against antibiotic-related diarrhea, so that could be a good choice.

Don’t forget the food for your gut bugs: prebiotics. You need to eat fermentable fibers and other prebiotics like resistant starch to support the growth and maintenance of the helpful bacteria that improve gut barrier function. Consider eating cooked and cooled potatoes, unheated potato starch, leeks, garlic, onions, green bananas, apples, pears, berries, and pretty much any fruit or vegetable you can get your hands on. Plenty of them are low-carb enough to work on a keto diet, if that’s your desire. Oh, and dark chocolate is a great source of fiber and polyphenols, which have prebiotic effects in the gut.

Incorporate intermittent fasting. Going without food for a spell gives your gut a break and induces autophagy, which can help with tissue healing.

Get dirty, too, to introduce potentially helpful bacteria. Go out and garden. Go barefoot at the park (do your due/doo diligence, of course) and practice tumbling, or roughhouse with your kids (or friends). Don’t immediately rush to wash your hands all the time (unless you’ve been handling raw meat and/or dog poop).

Whatever you do, don’t stress too much about the antibiotics you had to take. Stress is awful for gut health and you’ve already taken the antibiotics—which were probably necessary—so that ship has sailed.

If probiotics with prebiotics aren’t helping (or making things worse), you might want to try going the opposite direction—removing all plant foods and doing a carnivore diet for a few weeks. While I have doubts about the long term viability and safety of eschewing all plant foods, enough people have written to me about their great experiences resolving gut issues with a bout of carnivory that it’s worth trying.

When on a strict keto plan, why do I become so quickly fatigued while attempting a HIT sprint workout?

The first five seconds of a sprint are primarily powered by phosphocreatine (or creatine phosphate), a “quick burst” energy source that burns hot but disappears quickly. This is the stuff used to perform max effort Olympic lifts, short sprints, and other rapid expressions of maximum power. It doesn’t last very long and takes a couple minutes to replenish itself. A keto diet doesn’t affect our creatine phosphate levels. If anything, it should improve them if we’re eating meat.

After five seconds, anaerobic metabolism of muscle glycogen provides the lion’s share of your energy needs. The longer your sprint, the more glycogen you’ll burn. The less glycogen you carry in your muscles, the shorter your sprint. Because once you run out of creatine phosphate and glycogen, you’re left with aerobic metabolism—great for longer distances, not so great for max effort sprints.

Keto dieters tend to walk around with less glycogen in their muscles. If that’s the case, longer sprints will be harder.

If you want to keep sprinting:

Do shorter sprints. Try a 10-second hill sprint rather than a 20-second one. Really go hard. Heck, you can even do 5-second sprints and derive major benefits; just do more of them and make sure to recover in between. There’s no rule saying you have to sprint for 20-30 seconds.

Take longer rest periods. Give your muscles a chance to replenish more creatine phosphate (and take creatine or eat red meat and fish, which are the best sources of dietary creatine).

Eat 20-30 grams of carbs 30 minutes before a sprint session. See if it helps. Alternatively, you can eat the 20-30 grams of carbs after the sprint session to replenish lost glycogen stores (without really impacting your ketone adaptation, by the way).

Most people figure out their sprinting sweet spot while doing keto. They may have to play around with the dosages, durations, and rest periods, but you can usually make it work. Be open to trying new permutations.

If you knew you were going to have a poor nights sleep, what measures would you take to reduce some of the damage?

I would exercise hard that night. Normally, a bad night’s sleep tanks your insulin sensitivity the next day, giving you the insulin resistance and glucose tolerance of a diabetic. A good hard interval session the night before a bad night’s sleep, however, counters the next-day insulin resistance.

I would make the most of it. Don’t dawdle. Don’t beat yourself up because of the impending sleep deprivation. It’s going to happen. You have to accept it, not let it destroy you.

Enjoy it. A little-known acute treatment for depression is sleep deprivation. That’s right: a single night of sleep deprivation has been shown to ameliorate depression in patients with clinical depression. Sometimes the effect lasts up to several weeks. It’s not a long term or sustainable fix for clinical depression, obviously, and you can’t do it every single night—chronic sleep deprivation is a major risk factor for developing depression—but it can improve your mood if you give in to it.

I would set out a jar of cassia cinnamon. I always add cassia cinnamon to my coffee in the morning after bad sleep; cassia cinnamon the day after a bad night’s sleep attenuates the loss of insulin sensitivity and glucose tolerance.

That’s it for today, folks. Thanks for writing in and reading! If you have any input on today’s round of questions, let me know down below.

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References:

De vrese M, Kristen H, Rautenberg P, Laue C, Schrezenmeir J. Probiotic lactobacilli and bifidobacteria in a fermented milk product with added fruit preparation reduce antibiotic associated diarrhea and Helicobacter pylori activity. J Dairy Res. 2011;78(4):396-403.

Bekar O, Yilmaz Y, Gulten M. Kefir improves the efficacy and tolerability of triple therapy in eradicating Helicobacter pylori. J Med Food. 2011;14(4):344-7.

Erginkaya Z, Turhan EU, Tatl? D. Determination of antibiotic resistance of lactic acid bacteria isolated from traditional Turkish fermented dairy products. Iran J Vet Res. 2018;19(1):53-56.

Yang KM, Jiang ZY, Zheng CT, Wang L, Yang XF. Effect of Lactobacillus plantarum on diarrhea and intestinal barrier function of young piglets challenged with enterotoxigenic Escherichia coli K88. J Anim Sci. 2014;92(4):1496-503.

Jitomir J, Willoughby DS. Cassia cinnamon for the attenuation of glucose intolerance and insulin resistance resulting from sleep loss. J Med Food. 2009;12(3):467-72.

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The Definitive Guide To Autophagy (and 7 Ways To Induce It)

Biological systems are self-maintaining. They have to be. We don’t have maintenance workers, mechanics, troubleshooters that can “take a look inside” and make sure everything’s running smoothly. Doctors perform a kind of biological maintenance, but even they are working blind from the outside.

No, for life to sustain itself, it has to perform automatic maintenance work on its cells, tissues, organs, and biological processes. One of the most important types of biological maintenance is a process called autophagy.

Autophagy: the word comes from the Greek for “self-eating,” and that’s a very accurate description: Autophagy is when a cell consumes the parts of itself that are damaged or malfunctioning. Lysosomes—members of the innate immune system that also degrade pathogens—degrade the damaged cellular material, making it available for energy and other metabolites.  It’s cellular pruning, and it’s an important part of staving off the worst parts of the aging process.

In study after study, we find that impairment to or reductions of normal levels of autophagy are linked to almost every age-related degenerative disease and malady you can imagine.

  • Cancer: Autophagy can inhibit the establishment of cancer by removing malfunctioning cellular material before it becomes problematic. Once cancer is established, however, autophagy can enhance tumor growth.
  • Diabetes: Impaired autophagy enables the progression from obesity to diabetes via pancreatic beta cell degradation and insulin resistance. Impaired autophagy also accompanies the serious complications related to diabetes, like kidney disease and heart failure.
  • Heart disease: Autophagy plays an important role in all aspects of heart health.
  • Osteoporosis: Both human and animal studies indicate that autophagy dysfunction precedes osteoporosis.
  • Alzheimer’s disease: Early stage Alzheimer’s disease is linked to deficits in autophagy.
  • Muscle loss: Autophagy preserves muscle tissue; loss of autophagy begins the process of age-related muscle atrophy.

Okay, so autophagy is rather important. It’s fundamental to health.

But how does autophagy happen?

The way it’s supposed to happen is this:

Humans traditionally and historically lived in a very different food environment. Traditionally and historically, humans were feasters and fasters. While I don’t think our paleolithic ancestors were miserable, wretched, perpetually starving creatures scuttling from one rare meal to the next—the fossil records show incredibly robust remains, with powerful bones and healthy teeth and little sign of nutritional deficits—they also couldn’t stroll down to the local Whole Foods for a cart full of ingredients. Going without food from time to time was a fundamental aspect of human ancestral life.

They worked for their food. I don’t mean “sat in a cubicle to get a paycheck to spend on groceries.” I mean they expended calories to obtain food. They hunted—and sometimes came back empty handed. They dug and climbed and rooted around and gathered. They walked, ran, stalked, jumped, lifted. Movement was a necessity.

In short, they experienced energy deficits on a regular basis. And energy deficits, particularly sustained energy deficits, are the primary triggers for autophagy. Without energy deficits, you remain in fed mode and never quite hit the fasted mode required for autophagy.

Now compare that ancestral food environment to the modern food environment:

Almost no one goes hungry. Food is cheap and plentiful, with the tastiest and most calorie-rich stuff tending to be the cheapest and most widely available.

Few people have to physically work for their food. We drive to the store and walk a couple hundred steps, hand over some money, and—BOOM—obtain thirty thousand calories, just like that. Or someone comes to our house and delivers the food directly.

We eat all the time. Unless you set out to do it, chances are you’ll be grazing, snacking, and nibbling throughout the day. We’re in a perpetually fed state.

The average person in a modern society eating a modern industrial diet rarely goes long enough without eating something to trigger autophagy. Nor are they expending enough energy to create an energy deficit from the other end—the output. It’s understandable. If our ancestors were thrust into our current situation, many would fall all over themselves to take advantage of the modern food environment. But that doesn’t make it desirable, or good for you. It just means that figuring out how to trigger autophagy becomes that much more vital for modern humans.

Here are 7 ways to induce autophagy with regular lifestyle choices.

1) Fast

There’s no better way to quickly and reliably induce a large energy deficit than not eating anything at all. There are no definitive studies identifying “optimal” fasting guidelines for autophagy in humans. Longer fasts probably allow deeper levels of autophagy, but shorter fasts are no slouch.

2) Get Keto-Adapted

When you’re keto- and fat-adapted, it takes you less time to hit serious autophagy upon commencing a fast. You’re already halfway there.

3) Train Regularly

With exercise-related autophagy, the biggest effects are seen with lifelong training, not acute. In mice, for example, the mice who are subjected to lifelong exercise see the most autophagy-related benefits. In people, those who have played soccer (football) for their entire lives have far more autophagy-related markers of gene activity than people of the same age who have not trained their whole lives.

4) Train Hard

In studies of acute exercise-induced autophagy, the intensity of the exercise is the biggest predictor of autophagy—even more than whether the athletes are in the fed or fasted state.

5) Drink Coffee

At least in mice, both caffeinated and decaffeinated coffee induce autophagy in the liver, muscle tissue, and heart. This effect persists even when the coffee is given alongside ad libitum food. These mice didn’t have to fast for the coffee to induce autophagy.

Certain nutrients can trigger autophagy, too….

6) Eat Turmeric

Curcumin, the primary phytonutrient in turmeric, is especially effective at inducing autophagy in the mitochondria (mitophagy).

7) Consume Extra Virgin Olive Oil

The anticancer potential of its main antioxidant, oleuropein, likely occurs via autophagy.

Disclaimer: The autophagy/nutrient literature is anything but definitive. Most studies take place in test tube settings, not living humans. Eating some turmeric probably won’t flip a switch and trigger autophagy right away, but it won’t hurt.

Autophagy is a long game.

This can’t be underscored enough: Autophagy is a lifelong pursuit attained by regular doses of exercise and not overeating every time you sit down to a meal. Staying so ketotic your pee tests look like a Prince album cover, doing epic 7-day fasts every month, fasting every other day, making sure you end every day with fully depleted liver glycogen—while these strategies might be “effective,” obsessing over their measures to hit some “optimal” level of constant autophagy isn’t the point and is likely to activate or trigger neurotic behavior.

Besides, we don’t know what “optimal autophagy” looks like. Autophagy isn’t easy to measure in live humans. You can’t order an “autophagy test” from your doc. We don’t even know if more autophagy is necessarily better. There’s the fact that unchecked autophagy can actually increase existing cancer in some cases. There’s the fact that too much autophagy in the wrong place might be bad. We just don’t know very much. Autophagy is important. It’s good to have some happening. That’s what we have to go on.

Putting These Tips Into Practice

Autophagy happens largely when you just live a healthy lifestyle. Get some exercise and daily activity. Go hard every now and then. Sleep deeply. Recover well. Don’t eat carbohydrates you don’t need and haven’t earned (and I don’t just mean “earned through glycogen depleting-exercise”). Reach ketosis sometimes. Don’t eat more food than you need. Drink coffee, even decaf.

All those caveats aside, I see the utility in doing a big “autophagy session” a few times a year. Here’s how mine looks:

  1. Do a big training session incorporating strength training and sprints. Lots of intense bursts. This will trigger autophagy.
  2. Fast for two or three days. This will push autophagy even further.
  3. Stay busy throughout the fast. Take as many walks as possible. This will really ramp up the fat burning and get you quickly into ketosis, another autophagy trigger.
  4. Drink coffee throughout the fast. Coffee is a nice boost to autophagy. Decaf is fine.

I know people are often skeptical of using “Grok logic,” but it’s likely that most human ancestors experienced similar “perfect storms” of deprivation-induced autophagy on occasion throughout the year. You track an animal for a couple days and come up short, or it takes that long to make the kill. You nibble on various stimulants plucked from the land along the way. You walk a ton and sprint some, then lift heavy. And finally, maybe, you get to eat.

If you find yourself aging well, you’re on the right track. If you’re not progressing from obesity to diabetes, you’re good to go. If you’re maintaining and even building your muscle despite qualifying for the blue plate special, you’ve probably dipping into the autophagy pathway. If you’re thinking clearly, I wouldn’t worry. Obviously, we can’t really see what’s happening on the inside. But if everything you can verify is going well, keep it up.

That’s it for today, folks. If you have any more questions about autophagy, leave them down below and I’ll try to get to all of them in future posts.

Thanks for reading!

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References:

Yang ZJ, Chee CE, Huang S, Sinicrope FA. The role of autophagy in cancer: therapeutic implications. Mol Cancer Ther. 2011;10(9):1533-41.

Barlow AD, Thomas DC. Autophagy in diabetes: ?-cell dysfunction, insulin resistance, and complications. DNA Cell Biol. 2015;34(4):252-60.

Sasaki Y, Ikeda Y, Iwabayashi M, Akasaki Y, Ohishi M. The Impact of Autophagy on Cardiovascular Senescence and Diseases. Int Heart J. 2017;58(5):666-673.

Florencio-silva R, Sasso GR, Simões MJ, et al. Osteoporosis and autophagy: What is the relationship?. Rev Assoc Med Bras (1992). 2017;63(2):173-179.

Li Q, Liu Y, Sun M. Autophagy and Alzheimer’s Disease. Cell Mol Neurobiol. 2017;37(3):377-388.

Jiao J, Demontis F. Skeletal muscle autophagy and its role in sarcopenia and organismal aging. Curr Opin Pharmacol. 2017;34:1-6.

Schwalm C, Jamart C, Benoit N, et al. Activation of autophagy in human skeletal muscle is dependent on exercise intensity and AMPK activation. FASEB J. 2015;29(8):3515-26.

De oliveira MR, Jardim FR, Setzer WN, Nabavi SM, Nabavi SF. Curcumin, mitochondrial biogenesis, and mitophagy: Exploring recent data and indicating future needs. Biotechnol Adv. 2016;34(5):813-826.

Przychodzen P, Wyszkowska R, Gorzynik-debicka M, Kostrzewa T, Kuban-jankowska A, Gorska-ponikowska M. Anticancer Potential of Oleuropein, the Polyphenol of Olive Oil, With 2-Methoxyestradiol, Separately or in Combination, in Human Osteosarcoma Cells. Anticancer Res. 2019;39(3):1243-1251.

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Dear Mark: Fasting, Training, and Growth Hormone; Wear and Tear on the Arteries

For today’s edition of Dear Mark, I’m answering a couple of questions from the comment sections of the last couple weeks. First, it’s been established that fasting and exercise both raise growth hormone. What about fasted exercise—does that have an even stronger effect? And what about continuing to fast after your fasted workout? Then, I discuss the inevitability (or not) of wear and tear on the arteries from blood flow-induced shear stress. Is shear stress “bad,” or do certain factors make it worse?

Let’s dig in.

Marge asked:

So fasting raises growth hormone levels? Interesting. So does weight lifting. I’ll bet fasted weight workouts would be pretty powerful.

They do, and they are.

What’s even better is to work out in a fasted state and keep fasting after the workout. This keeps the GH spike going even longer. And in my “just so story” imagination—which is actually quite accurate, judging from real world hunter-gatherers—it mirrors the circumstances of our Paleolithic ancestors. You’d get up early to go hunting without having eaten. You’d expend a lot of energy on the hunt. You’d make the kill, procure the food. And then you’d bring it back to camp to finally eat. Maybe you’d pass the heart and liver around the circle before heading back. And sometimes, you just didn’t make the kill. You didn’t eat at all.

Makes sense, right? Fasting, doing something physical, and continuing to fast shouldn’t be a monumental undertaking. It should be well within the realm of possibility for the average person.

Now, I wouldn’t do this all the time. There is such a thing as too much of a good thing. A hormetic stressor can become a plain old stressor if it’s prolonged for too long. Instead, I would throw post-fasted-workout fasting in on an occasional basis.

Nor would I expect huge “gains” from this. Physiological growth hormone production won’t make you huge or shredded. In fact, workout-related increases in testosterone and growth hormone don’t actually correlate with gains in hypertrophy. Instead, I’d expect more intangible benefits, things you won’t notice right away. It’s important in cognition. It helps maintain bone health, organ reserve, and general cellular regeneration. It’s great for burning fat.

Growth hormone does way more than promote overt muscular growth.

Steve wrote:

In the linked article it says:

“Endothelial cell dysfunction is an initial step in atherosclerotic lesion formation and is more likely to occur at arterial curves and branches that are subjected to low shear stress and disturbed blood flow (atherosclerosis prone areas) (7,8). These mechanical stimuli activate signaling pathways leading to a dysfunctional endothelium lining that is barrier compromised, prothrombotic, and proinflammatory.

So it seems that endothelial disfunction comes first, triggered by blood flow stresses. It’s common wear and tear in exposed areas. The patched knees on jeans. Managing endothelial health and healing may slow or diminish rate of progression or is it mostly too late for that?

I’m not a doctor. This isn’t medical advice. This is just speculation.

I find it rather hard to believe that healthy arteries are inherently fragile and prone to damage and incapable of weathering the “stress” of blood flowing through them, even at the “susceptible” curves. I find it more likely that poor health, poor diets, and poor lifestyles make us more susceptible to otherwise normal stresses.

Do the mechanical stimuli weaken the endothelium in people with healthy levels of nitric oxide production? Or are we talking about people whose poor nitric oxide status is exacerbating the damaging blood flow patterns, leaving their endothelium vulnerable to atherosclerosis?

Think about how much context matters in our response to stimuli. If you’re shy around girls, a school dance will be a traumatic experience. If you’re comfortable around girls, a school dance will be a great experience. If you’re weak, lifting a barbell will be scary, and you may injure yourself. If you’re strong, lifting a barbell will be second nature, and you may get stronger. The baseline context determines the quality of the response.

I’d argue that blood flowing through your arteries should be a commonplace occurrence. It shouldn’t be a traumatic experience. Now, maybe I’m wrong. Maybe it is stressful regardless of the baseline endothelial health and the amount of nitric oxide you produce. Maybe it’s just a matter of time. But:

  • We know that, as you quote, atherosclerosis tends to occur at bends and curves of the arteries—the places most likely to be subject to “disturbed flow” patterns.
  • We know that “laminar flow”—blood flowing smoothly through the artery—is protective of the endothelial wall, promoting anti-inflammatory effects and making the endothelium more resistant to damage.
  • We know that “disturbed flow” has an opposing effect on endothelial health, promoting inflammatory effects and rendering the endothelium more susceptible to damage. This increases atherosclerosis.
  • The question I’m wondering is if “disturbed flow” at the curves and bends of the arteries is inevitable or not. And if disturbed flow is always “bad.”
  • We know that hyperglycemia—high blood sugar—makes disturbed blood flow more damaging to arterial walls. Diabetics have higher rates of atherosclerosis because their elevated blood sugar interacts with disturbed blood flow patterns.
  • We know that nitric oxide increases vasodilation in response to shear stress—widening the arteries to accommodate the increased stress and mitigate the damage done. We know that people with hypertension don’t get the same vasodilatory benefits from nitric oxide.
  • We know that “functional increases” of shear stress attained via exercise increase nitric oxide and oxygen production and induce autophagy (cellular cleanup) in the endothelial walls.

That sounds like there are a lot of factors that increases and mitigate the effects of shear stress on the endothelial wall. It sounds like some factors make shear stress more damaging, and some factors make it less. There may even be factors, like exercise, that make shear stress healthy.

This topic is really pretty interesting to me. It deserves a deeper dive, don’t you think?

What about you, folks? What’s your take on fasted workouts and GH secretion? Ever try one?

And do you think your arteries are doomed to fall apart at the seams?

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References:

Nyberg F, Hallberg M. Growth hormone and cognitive function. Nat Rev Endocrinol. 2013;9(6):357-65.

Park SK, La salle DT, Cerbie J, et al. Elevated arterial shear rate increases indexes of endothelial cell autophagy and nitric oxide synthase activation in humans. Am J Physiol Heart Circ Physiol. 2019;316(1):H106-H112.

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