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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4 Misunderstandings About Carbs and Stress

The relationship between stress and carbohydrates is confusing, with seemingly contradictory arguments bouncing around the online health sphere.

There are those who say high-carb diets cause stress, and that eating more fat and fewer carbs is the solution.

There are those who say high-fat diets increase stress and eating carbs ameliorates it.

Who’s right? They can’t both be right, can they?

Well…

You’d be surprised.

Let’s dig into four common carb questions and assertions.

“Stress Increases Carb Cravings.”

This is well-established. You have a terrible day at the office, your kids have appointments twenty miles apart within fifteen minutes of each other, the traffic is backed up to your driveway, you’re late for work, the dog needs a walk, you haven’t even thought about what to make for dinner, you slept four hours last night—it adds up. People deal with a lot. And in that moment, a carbohydrate-based snack really does seem to take the edge off.

Across millions of years of hominid evolution, the human stress response developed in the context of real-world, short-term, and infrequent but intense stressors: battles, hunts, freak injuries, dangerous animal encounters, interpersonal conflicts. These were situations that demanded heightened senses, available fuel, and a rapid heart rate to deliver everything to the tissues that needed to move and act. It makes perfect sense for your body to pump out adrenaline to increase fat burning and glucose in the blood—you need that fuel to deal with the situation. It also makes sense for your body to follow that up with a blast of cortisol, which makes you crave high-carb junk food to replace the fuel you utilized. The problem is that our modern stressors are too frequent, they aren’t physically demanding, we aren’t utilizing the fuel we mobilize, and we have no real need for the carb cravings that come after.

What happens when we eat too many carbs that we never actually needed?

We get fat. Cellular energy supply becomes overloaded, impairing our mitochondria’s ability to process energy efficiently. This degrades metabolic flexibility—the ability to switch between different fuel sources—preventing us from burning the fat on our bodies in between meals. We become reliant on those carbs, and when we don’t get them fast enough, our bodies perceive that as a major stressor.

So while giving in to carb cravings can reduce stress in the short-term, it sets us up for longer-term, more chronic stress.

“What About Gluconeogenesis? Isn’t That a Stress Response?”

It can be.

A primary goal of cortisol is to increase glucose availability. It does this through multiple avenues. One I just mentioned is to increase carb cravings. Another is to make you insulin resistant, thereby preventing insulin from sucking up blood glucose. Gluconeogenesis—the creation of glucose from amino acids and other substrates—is another.

If you’re a sugar-burner, stressful situations will increase carb cravings, induce gluconeogenesis, and may even make you insulin resistant. If you’re fat-adapted, the story shifts.

A fat-adapted person will have ketones and fatty acids available to provide energy in between meals. A fat-adapted person will have ketones and fatty acids available to provide energy in stressful situations. A fat-adapted person will be able to utilize those ketones and fatty acids during stressful situations—their mitochondria will literally be primed to utilize those fuels, not just glucose. A fat-adapted person is less likely to perceive carbohydrate shortages as stress shortages because they’ve got all this other fuel available to burn.

This adaptation doesn’t happen overnight. If your diet is low-carb or keto, but your body is still reliant on sugar, you will perceive reduced carb availability as a stressor. That’s one of the hallmarks of the keto flu, and it’s one reason why some people have extended keto flu—their bodies are still expecting and demanding glucose.

Some people never get over the carb cravings; they never fully adapt. This is the subset of the population that doesn’t function or perform well on a long-term ketogenic diet. The cause is unknown, at least for now (I suspect it has to do with recent ancestry and genetic proclivities), but what matters is that these people exist. For them, a long-term keto or very low carb diet approach will probably always be stressful. But even in these folks, spending some time in ketosis—through short term low-carb eating, intermittent fasting, or even extended low-level endurance activity that primarily burns fat—is a good idea that will reduce stress and improve overall resilience.

“But Carbs Make Exercise Less Stressful!”

Exercise is stressful to begin with. But then you adapt to the stress and overcome it—and end up stronger, fitter, and faster than before. Without the stress, working out doesn’t work. A legitimate method for increasing your work capacity is to train-low (carb), race-high (carb). Athletes have been doing this for decades—training in a low-carb state to get better at performing without ample muscle glycogen, then going into a race with full glycogen reserves and the ability to perform without glycogen. Exercising in that low-glycogen state is stressful, but that’s the whole point. It makes them better, stronger, faster, and it conserves glycogen for when they really need it.

If you consistently perform glucose-intensive high-intensity anaerobic activity for extended periods of time—CrossFit style WODs done 3-5 times per week, for example—you will run up a glucose debt and should replenish some of the carbohydrates you expend or risk cortisol spikes. Fat-adaptation can improve your tolerance of anaerobic activity in a low-glucose state, but there’s a breaking point, a physiological limit.

Eat the carbs you earn. This is a subtle point I don’t often see made. The reverse is widely understood—don’t eat the carbs you don’t earn—because millions of obese and overweight people do that every day. It’s a big reason why we’re so overweight. But if you fail to eat the carbs you earn through intense, protracted physical activity, you’re creating an undeniable glycogen deficiency that your body may perceive as a stressor. It may turn out that fully fat- and keto-adapted athletes can perform intense medium-to-long-term activities at high levels, and there’s some indication that this is the case, but for the time being it appears that eating the carbs you earn can stave off the stress.

“Low-Carb Diets Are Stressful For Women.”

There’s a glimmer of truth here. Allow me to explain.

Women are inherently more sensitive to caloric fluctuations than men…on average. The reason is sheer biology. Human evolution is concerned with fertility and reproduction. Can you produce, foster, and support viable offspring? Awesome. Natural selection deems you fit.

To fulfill their biological role, men have to produce sperm. They can do so almost indefinitely. They don’t run out; they just make more. If a batch is damaged due to poor lifestyle or dietary choices, there’s more on the way. After a man gets someone pregnant, his biological involvement with the growing baby is done. What or when he eats has no impact on the survival of the growing baby.

To fulfill theirs, women have a finite number of eggs, or “chances.” Once an egg is gone, there’s no replacing it.

And so the body seeks to inculcate the egg from environmental insults.

When you are preparing to get pregnant, your body needs extra nutrients to build up a reserve and “prime the pump.”

When you are pregnant, the growing baby needs a reliable and constant stream of nutrients for almost a year.

After you’ve given birth, the growing newborn needs breastmilk. To make that milk requires additional calories and extra doses of specific nutrients. Modern technology allows us to skip nursing and go straight to the bottle, but your body doesn’t “know” that.

It all points to women being more finely attuned to caloric deficits. For example, women’s levels of ghrelin, the hunger hormone, are quicker to rise after meals. Even if you’re never going to have kids, your body is still wired to protect against these caloric fluctuations.

Where do carbs come in?

One’s carbohydrate consumption is uniquely hewed to our sense of caloric sufficiency. If carbs are plentiful, your body perceives that as a signal of environmental plenty: the weather is good, the plants are producing, the trees are bearing fruit, the men are bringing back lots of honey. Life is good. It’s the perfect time to get pregnant. Above all other macronutrients, carbohydrate consumption increases the short-term expression of leptin, a satiety hormone that signals the presence of incoming calories, caloric sufficiency, and environmental plenty.

There’s also the issue of extreme satiety. Low-carb diets often become low-calorie diets without you even trying. That’s why they work so well for fat loss, by inadvertently reducing the amount of food you eat and increasing satiety. But for some women, especially those at or approaching their ideal weight, going too low in calories can increase stress.

Summing Up…

Are you unable to access your own body fat in between meals for energy? Then you’ll be a ball of stress unless you can get those Jolly Ranchers unwrapped quickly enough. It’ll be a constant battle. And yeah, if you keep pumping yourself full of carbs to keep your blood glucose topped off, you’ll keep stress at bay—but you’ll always be teetering on that precipice.

Are you exercising? Then you should strike a balance between gaining the adaptive benefits of training in a low-carbohydrate state and eating the carbs you earn.

Are you a woman? Then you’re probably more sensitive to diet-induced stress and may benefit from occasional carbohydrate refeeds. You should watch out for excessive satiety on ketogenic diets, which is great for fat loss but can lead to stress issues down the line if calories get too low.

The relationship between carbohydrates and stress isn’t exactly straightforward, but it is navigable. Hopefully after today you have a better idea of where you stand in the relationship.

What’s been your experience with stress and carbohydrates? Has your tolerance for stress gone up or down since going low-carb or keto? Thanks for stopping in today.

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References:

Mcallister MJ, Webb HE, Tidwell DK, et al. Exogenous Carbohydrate Reduces Cortisol Response from Combined Mental and Physical Stress. Int J Sports Med. 2016;37(14):1159-1165.

Dirlewanger M, Di vetta V, Guenat E, et al. Effects of short-term carbohydrate or fat overfeeding on energy expenditure and plasma leptin concentrations in healthy female subjects. Int J Obes Relat Metab Disord. 2000;24(11):1413-8.

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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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