Have you heard? There’s a new “red meat will kill you” study. This time, it’s colorectal cancer.
Here’s the press release.
Here’s the full study.
I covered this a couple Sundays ago in “Sunday with Sisson.” If you haven’t signed up for that, I’d recommend it. SWS is where I delve into my habits, practices, and observations, health-related and health-unrelated—stuff you won’t find on the blog. Anyway, I thought I’d expand on my response to that study here today.
How the Study Was Conducted
It’s the basic story you see with most of these observational studies. Around 175,000 or so people were asked to recall what they ate on a regular basis—a food frequency questionnaire. This is the exact questionnaire, in fact. The research team took the answers, measured some baseline characteristics of all the subjects—socioeconomic status, exercise levels, whether they smoked, education level, occupation, family history of colorectal cancer, and a few others—and then followed up with participants an average of 5.7 years later to see how many had developed colorectal cancer.
What the Study “Showed”
Those who had moderate amounts of red meat had a 20% higher chance of getting cancer.
And in the end, the increased risk was a relative risk. It wasn’t a 20% absolute increase in risk. It was a relative increase in risk. The subjects started with a 0.5% risk of getting bowel cancer. In those who ate the most processed meat and red meat, that risk increased 20%—to 0.6%!
From 0.5 to 0.6%. Sure, that’s an increase, but is it something to overhaul your entire diet for? To give up the best sources of zinc, iron, B vitamins, protein, carnosine, creatine? All that for a measly 0.1% that hasn’t even been established as causal?
Study Findings Most News Outlets Won’t Include
One head scratcher that leaps out: the link between unprocessed red meat and colon cancer was not actually statistically significant. Only processed meat was significantly linked to colon cancer.
Another head scratcher: red meat, whether processed or unprocessed, had no significant association with colorectal cancer in women. Why didn’t they highlight the fact that in women, eating red meat was completely unrelated? That’s half the world’s population. That’s you or your mom, your daughter, your grandmother, your girlfriend. And unless they were to look at the full study and read the fine print, they’d never know that red meat actually had the opposite relationship. You’d think the authors would want to mention that in the abstract or see that the press releases and media treatments highlighted that fact.
It’s probably because mentioning that red meat was neutral in women and had no statistically significant link to colon cancer in men and women would have destroyed their case for red meat as an independent carcinogen. See, carcinogens are supposed to be carcinogens. There are many meaningful differences between men and women, but a poison is a poison.
What’s the proposed mechanism for red meat triggering colon cancer in men but not in women? If they didn’t have one (and I imagine they wouldn’t have mentioned it if they did), then there’s probably something else going on.
Besides, the literature is far from unequivocal.
What Other Research Says About Red Meat and Bowel Cancer
In analyses that include consideration of cooking methods and other mitigating factors, red meat has no relationship with colon cancer.
Or what about this study, where colon cancer patients were more likely to eat red meat, but less likely to have type 2 diabetes? Should people avoid red meat and work toward getting diagnosed with type 2 diabetes?
Or how about this study, which found no difference in colorectal cancer rates between people who ate red meat-free diets and people who ate diets containing red meat? Shouldn’t the diet without any red meat at all have some effect?
Or this classic study, where rats on a bacon-based diet had the lowest rates of colon cancer. In fact, bacon protected them from colon cancer after they were dosed with a colon cancer promoter, while rats on normal “healthy” chow were not.
The Blind Spot In Red Meat Research
I don’t need to go into all the confounding factors that might predispose conventional red meat lovers to bowel cancer. Nor will I mention that it’s impossible to fully control for variables like the buns and bread and fries you eat the red meat with and the industrial seed oils it’s cooked in.
That last bit is crucial: the seed oils. It’s what nearly every cancer researcher misses. It’s not just a minor variable; it’s quite possibly the most important determinant of whether meat is carcinogenic in the colon or not. Heme iron—the compound unique to red meat that usually gets the blame for any increase in cancer—is most carcinogenic in the presence of the omega-6 fatty acid linoleic acid.
In one study, feeding heme iron to rats promoted colon cancer only when fed alongside high-linoleic acid safflower oil. Feeding MUFA-rich and far more oxidatively-stable olive oil alongside the heme prevented the colon carcinogenesis.
Another study had similar results, finding that meats containing medium to high amounts of heme—beef and beef blood sausage—promoted carcinogenic conditions in the colon when the fat sources were linoleic acid-rich corn and soybean oil.
And most recently is this paper. Mice were split into three groups. One group got heme iron plus omega-6 PUFA (from safflower oil). One group got heme iron plus omega-3 PUFA (from fish oil). The third group got heme iron plus saturated fat (from fully hydrogenated coconut oil, which contains zero PUFA). To determine the carcinogenicity of each feeding regimen, the researchers analyzed the effect the animals’ fecal water (which is exactly what it sounds like) had on colon cells. The fecal water of both PUFA groups was full of carcinogenic indicators and lipid oxidation byproducts, and exposing colonic epithelial cells to fecal water from PUFA-fed mice was toxic. The coconut oil-derived fecal water had no markers of toxicity or lipid oxidation.
I never see these (animal) studies cited in observational studies of meat and colon cancer. I think that’s a huge blindspot, and it’s one of the reasons I rarely put any stock in these scary-sounding studies.
That’s it for today, folks. Thanks for reading. Now go enjoy a steak.
Bylsma LC, Alexander DD. A review and meta-analysis of prospective studies of red and processed meat, meat cooking methods, heme iron, heterocyclic amines and prostate cancer. Nutr J. 2015;14:125.
Alsheridah N, Akhtar S. Diet, obesity and colorectal carcinoma risk: results from a national cancer registry-based middle-eastern study. BMC Cancer. 2018;18(1):1227.
Rada-fernandez de jauregui D, Evans CEL, Jones P, Greenwood DC, Hancock N, Cade JE. Common dietary patterns and risk of cancers of the colon and rectum: Analysis from the United Kingdom Women’s Cohort Study (UKWCS). Int J Cancer. 2018;143(4):773-781.
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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.
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.
No studies have looked at the direct effects of ketones on menstruation.
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 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 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.
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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While some keto or low-carb proponents claim fiber is useless at best and actively harmful at worst, I come down on the side that says fiber is probably helpful for most people. Some folks have persistently better responses to low- or no-fiber keto diets, and I won’t argue with that—I’ve seen it happen and I’ve read the studies where de-emphasizing fiber can actually improve constipation, for example.
I’ll just say that I have an opposite reaction, and, most importantly, I love eating a variety of plant foods that also happen to contain a ton of great nutrients in addition to fiber.
Do I buy into the idea that fiber is important because it is every human being’s responsibility to produce as much colonic bulk as humanly possible? No.
Do I think we should be consistently pushing the limits of our digestive tracts, performing feats of bathroom heroism so momentous they border on Herculean, and making sure the toilet bowl buckles beneath us? No.
The real value of fiber lies not in its coarseness, its tendency to form colonic bulk, to keep us topped off. The true value lies in its fermentability.A fermentable fiber is a prebiotic fiber—fiber that feeds our gut bacteria.
I won’t get into the many roles our gut bacteria play in our health today (I’ve covered that before. 1, 2, 3).
I will, however, explain why we need to be feeding our gut bacteria. Our gut bacteria form a physical barrier against incursions and colonization by pathogenic bacteria; they take up room along the gut lining so pathogens can’t. If we don’t feed our gut bacteria with prebiotics, it won’t be around to protect us. After antibiotic treatment where both good and bad gut flora are indiscriminately targeted and wiped out, pathogenic obesity-promoting bacteria take advantage of the open space. That’s a worst-case scenario, but it shows what can happen when the harmony of the gut is disturbed by antibiotics or, to a less extent, a lack of fermentable prebiotic fibers.
When our gut bacteria eat prebiotics, they also give off metabolites like butyric acid—a short chain fatty acid that our colonic cells use as an energy source and which improves metabolic health.
Gut bacteria also convert antinutrients like phytic acid into nutrients like inositol. The almond meal-obsessed keto eater would do well to have a powerful gut biome set up to convert all that phytic acid to inositol.
Now, some writers will come up with specific blends of fibers, powders and gums to create the “optimal” prebiotic diet for your gut bacteria, but that’s pretty silly. The gut is a complicated place. We’ve barely begun to even identify all its inhabitants. To think we know the precise blend of isolated fiber that will make them flourish, and then act on that, is a mistake.
A better option is to eat foods that contain fiber. Some of the prebiotic fibrous foods with the best nutrient profiles also happen to be extremely keto-friendly.
1) Almonds and Pistachios
Nuts are usually favored in health-conscious circles for a few reasons. They like the monounsaturated fat. They like the mineral profile, or the complete protein, or their ability to dissemble into nut meals and form baked goods. But what gets short shrift is the fiber content. Now, I can’t speak for other nuts, but almonds and pistachios in particular contain fiber with potent prebiotic effects. People who eat almonds and to an even greater extent pistachios end up with improved gut bacteria profiles.
2) Green Bananas
Ripe bananas are difficult to squeeze into a ketogenic diet. The green banana—an unripe one—is mostly resistant starch, a type of starch that cannot be digested and travels untouched until colonic bacteria metabolize it. It’s one of the best stimulators we know of butyric acid production. And sure, you could do a spoonful of raw potato starch to get your resistant starch, but the beauty of the green banana is that it also provides potassium, another nutrient that some find difficult to obtain and stay keto.
3) Wild Blueberries
Blackberries, boysenberries, raspberries, and strawberries are all loaded with fiber, and you should eat them. They’re lower carb than you think, they’re loaded with polyphenols, and topped with some real whipped cream they make a fantastic dessert. But wild blueberries are special. They’re smaller than other berries, which increases the amount of skin per ounce you get, and skin is where all the polyphenols and fiber lie. Heck, even the blueberry’s polyphenols have prebiotic effects on the gut biome.
A few years ago, I wrote a whole post on mushrooms. Suffice it to say, they’re quite wonderful, bordering on magical. I did not discuss the fiber they contain. It turns out that all the various mushroom polysaccharides/fibers, including beta-glucans, mannans, chitin, xylans, and galactans also act as potent prebiotics that improve the health of the host.
Your standard avocado has about 12-15 grams of fiber, if you eat the whole thing. I
Great with chili powder, salt, and lime juice, jicama is about 11 grams of carbs per cup, but half of those are inulin, a potent prebiotic fiber with a tendency to really ramp up butyrate production.
Onions are another fantastic source of inulin. They go into almost every dish of every cuisine, so there’s no excuse not to be eating onions.
I’ve been known to treat garlic like a vegetable, roasting an entire cast iron pan full until brown and sweet and chewy. They’re another great source of prebiotic fiber.
Leeks have more inulin than onions. Try them crispy in egg scrambles.
Broccolini is a major part of my favorite meal of the day—my Big-Ass Keto Salad. Broccoli (and cruciferous vegetables in general) has been shown to have modulatory effects on the gut biome.
Kraut gives you two in one. It’s a fermented food, which is great for the gut biome. And it’s cabbage, which is very fibrous. Even pasteurized kraut improves gut health.
12) Dark Chocolate
Dark chocolate, the good stuff with a high cacao content (85%+) and low sugar content, is an incredible source of prebiotic fiber. Eat more of it.
13) Animal Fiber
Obligate carnivores like cheetahs who don’t eat any plants (willingly) still have gut bacteria. These gut bacteria thrive on “animal fiber,” the gristle and cartilage and other bits of connective tissue that comprise a good 20-30% of the walking weight of a prey animal. Humans are not obligate carnivores, but eating the entire animal has been a mainstay of advanced hominid existence for millions of years. I find it very likely that something, someone, somewhere inside our guts is breaking down the animal fiber we eat—so you’d better be eating some!
Not so tough, is it? It’s not like I’m suggesting you load up on bran muffins, psyllium smoothies. I don’t want you dumping flax meal into everything or munching on those awful fiber gummies. Just eat some basic, healthy, low-carb plant matter—foods that don’t really scream “fiber”—and the rest will take care of itself.
What’s your favorite low-carb source of fiber? Let me know down below.
Thanks for reading, everyone.
Hernández E, Bargiela R, Diez MS, et al. Functional consequences of microbial shifts in the human gastrointestinal tract linked to antibiotic treatment and obesity. Gut Microbes. 2013;4(4):306-15.
Ukhanova M, Wang X, Baer DJ, Novotny JA, Fredborg M, Mai V. Effects of almond and pistachio consumption on gut microbiota composition in a randomised cross-over human feeding study. Br J Nutr. 2014;111(12):2146-52.
Jiao X, Wang Y, Lin Y, et al. Blueberry polyphenols extract as a potential prebiotic with anti-obesity effects on C57BL/6 J mice by modulating the gut microbiota. J Nutr Biochem. 2019;64:88-100.
Jayachandran M, Xiao J, Xu B. A Critical Review on Health Promoting Benefits of Edible Mushrooms through Gut Microbiota. Int J Mol Sci. 2017;18(9)
Nielsen ES, Garnås E, Jensen KJ, et al. Lacto-fermented sauerkraut improves symptoms in IBS patients independent of product pasteurisation – a pilot study. Food Funct. 2018;9(10):5323-5335.
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GMO soybean oil (made to have less PUFA and more MUFA) causes less obesity than conventional soybean oil
12 weeks of keto improve cognitive function, eating behavior, physical performance, and metabolic health in obese people.
Older adults are still capable of growing new neurons, except if they have Alzheimer’s.
More inflammation, more impulsivity.
Want to bulk up your pet mouse’s colon tumors? Give him American cola, not Mexican.
A combo of EGCG and ferulic acid reverses cognitive deficits in mice with Alzheimer’s.
New Primal Blueprint Podcasts
Episode 322: Dr. Robert Glover: Host Elle Russ chats with Dr. Robert Glover, author of No More Mr. Nice Guy.
Health Coach Radio Episode 5: Ste Lane: Hosts Laura Rupsis and Erin Power chat with Ste Lane, a Primal health coach highlighting the importance and vitality of mindset in the pursuit of health and fitness.
Each week, select Mark’s Daily Apple blog posts are prepared as Primal Blueprint Podcasts. Need to catch up on reading, but don’t have the time? Prefer to listen to articles while on the go? Check out the new blog post podcasts below, and subscribe to the Primal Blueprint Podcast here so you never miss an episode.
The plaintiffs in an ongoing trial against Monsanto allege that the agrochemical company planted a mole in an independent lab to fake safety data for Roundup.
Primatologist Frans de Waal on human exceptionalism.
Interesting Blog Posts
How the timing of your training affects circadian rhythm.
These forest monks have it figured out.
Another “vegan” Youtuber got caught eating animal foods. You’ll never guess what happened next.
In last week’s SWS, I mentioned a product Kickstarter for Thin Ice, a wearable cold vest that claims to trigger thermogenesis. I want to make clear that I wasn’t recommending it, just expressing interest in the concept. I have no connection to the brand and no clue if the product actually does what it claims.
Look for a coffee-related giveaway this coming Monday on the blog. Has nothing to do with April Fool’s. (I never joke about coffee.)
Why are we “still waiting” for a male birth control pill? Maybe because the only viable one they’re trying to push lowers (an already historically low) testosterone.
Workism isn’t working.
Shmita, the ancient Jewish practice of agriculture.
Things I’m Up to and Interested In
We can do epidemiology, too: A new study on carb consumption and heart disease finds that “strong and probably causal” links between coronary heart disease and glycemic load/index “exist within populations.”
Concept I found interesting: Sex differences in pain sensations.
This is worrisome: A “sex recession.”
I’m intrigued: “In order to reveal how ‘peculiar a creature we are,’ Stewart-Williams offers an alien scientist’s perspective on modern human civilization, studying us as we would study animals in the wild.”
I’d send my kids here (if I had anymore of the right age): The first USDA-certified organic high school where learning to farm is a graduation requirement.
Question I’m Asking
Men: Would you take a birth control pill that lowers testosterone? Women: Would you want your men to take a birth control that lowers testosterone? And I guess this follows, too…how do you feel about women’s birth control pills’ effect on your own hormonal picture?
One year ago (Mar 24– Mar 30)
Comment of the Week
“‘Physiological Functions and Metabolism of Endogenous Ethanol and Acetaldehyde in the Reindeer’ is a bit of light reading that pairs well with a smokey single malt from Islay on a cold winter night.”
– I’m waiting for someone to bottle endogenous reindeer moonshine, Aaron.
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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.
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:
Do a big training session incorporating strength training and sprints. Lots of intense bursts. This will trigger autophagy.
Fast for two or three days. This will push autophagy even further.
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.
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!
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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We get lots of questions about how a ketogenic diet works in the context of exercise: Is it possible to maintain one’s fitness (strength, endurance, performance) and also drop one’s carb intake to ketogenic levels? Is it advisable? Will it help me lose weight faster?
Mark already addressed some of these topics, but it’s clear that many people still feel uncertain about how to pair a keto diet with their current workout routine.
Rather than write a single behemoth post, I’m going to tackle this in two parts. For today, let me talk keto and cardio, specifically how keto works for the average fitness enthusiast who thinks more in terms of general exercise. In a couple weeks I’ll follow up with a post on keto for runners and other endurance types who tend to focus on training programs and racing.
So, keto and cardio… This is for people who like to attend group fitness classes, or go out for jogs or spins on the bike, or do a mix of low heart rate exercise with occasional bouts of HIIT. (This is a problem with the term “cardio”—it can mean so many things.)
You probably already know Mark’s stance on cardio: avoid chronic cardio exercise patterns. The Primal Blueprint approach to exercise comprises lots of everyday movement, lifting heavy things, and occasionally going all out. If you simplymustdo cardio, most of these sessions should be conducted at an aerobic heart rate not higher than 180-age, as detailed in the Primal Endurance book. So, with the caveat that cardio exercise in the traditional sense of slogging away on an elliptical machine or treadmill doesn’t jibe with the Primal Blueprint approach, let’s get to some frequently asked questions.
Will My Workouts Suffer When I Go Keto?
This is a common concern because some peopledoreport that they feel sluggish when they first go keto. And yes, you might feel like your performance in the gym (cardio, strength, HIIT—all of it) takes a hit in the first few weeks of keto. Rest assured that this is a temporary dip as your body becomes efficient at using fat and ketones for energy in the absence of incoming carbs (glucose). It’s a learning process for your body, so to speak.
The more glycolytic your workouts, the more you are going to notice this. Prolonged, difficult workouts that fall into the category of chronic cardio or “black hole” sessions are especially likely to suffer.
To help mitigate temporary performance decrements during the transition to keto:
Dial back the intensity and/or frequency of your workouts for a few weeks. Trade some of your more intense cardio (and strength) sessions for walks, yoga or Pilates, or other gentle forms of movement.
Mind your electrolytes. If you are feeling weak or lightheaded, if you get a headache, or you just feel “off,” this is likely due to electrolyte imbalance. Try adding ¼ – ½ teaspoon of salt to a glass of water with lemon juice and see if that helps. You want to make sure you are getting 4.5 grams of sodium, 300-400 mg of magnesium, and 1-2 grams of potassium each day on top of your normal food.
While your body is making the switch, give it plenty of fuel. Consume extra fat and eat plenty of calories. If fat loss is a goal, you can adjust your macros and calories as needed once you are feeling in the groove with keto.
Tough it out. Don’t cave and add carbs in the first few weeks (see the next point). Know that this is temporary, and you should be back to normal within three to six weeks.
Do I Need To Add Back Carbs To Fuel My Workouts?
During the first few weeks of starting keto, you should notadd back carbs. It is important to create a low-glucose, low-insulin environment to promote ketogenesis and the adaptations that accompany a ketogenic state. If your workouts are too hard right now, the correct answer is to change your workouts, not to increase your carbs.
After you have done a dedicated period of aminimumthree weeks of strict keto—six or more is even better—you should be feeling better during your workouts if you are not engaging in prolonged, chronic cardio activities. (It might take longer to adapt to longer endurance training, as we will discuss in the next installment.) At this point you have some options:
One, you can continue in strict ketosis (less than 50 grams of carb per day) as long as you are feeling good.
Two, you can start experimenting with eating carbs strategically before your workouts. This is known as atargeted ketoapproach. There are various ways of implementing this, but the basic formula is that you would ingest 25-30 grams of glucose or dextrose (not fructose) about half an hour before high-intensity workouts to replenish muscle glycogen.
There are a few caveats here. First, most sources of glucose/dextrose are not Primal (think hard candy, gels). Probably the closest is pure maple syrup, but that also delivers a hit of fructose. If you are a Primal purist, you will have to decide if this is a compromise you want to make. Second, people tend to overestimate the degree to which they are actually low on glycogen and how much it matters. It is a common misconception that once you go keto you have “no glycogen.” While muscle glycogen storesarereduced, your tanks are probably still at least 50% full, and perhaps on par with non-ketogenic folks if you have been keto for a long time. Furthermore, the average low-to-medium intensity cardio session isn’t trulydepletingglycogen. Remember, the point of becoming fat- and keto-adapted is that you burn predominantly fat and ketones at these lower intensities, sparing glycogen. You have to go hard and/or long to really burn through your muscle glycogen stores. Thus, you should target pre-workout carbs only before truly high-intensity sessions.
Instead of adding simple carbs before workouts, another option if you feel like you need more carbs is to add back nutrient-dense carbs after workouts, when insulin sensitivity is increased. This might make sense if you feel like your ability to recover between workouts is lagging, or you want to recover quickly because you have back-to-back hard sessions planned. In either case—adding carbs before or after exercise—the amount you add should be proportional to the difficulty (intensity) of the workout. You don’t need to carb up for your yin yoga class, for example.
Lastly, if you are feeling underpowered during exercise, instead of adding back carbs you can experiment with adding more protein and/or fat. Some people report good success with “protein ups” timed around heavier workout days.
Will Adding Keto to My Cardio Routine Help Me Lose Weight?
Maybe. It’s a common refrain that “abs are built in the kitchen,” meaning that your food plays a bigger role in fat loss than does your exercise. This isn’t to say exercise is unimportant; it does matter. A caloric deficit is necessary to lose body fat, and exercise is one way to create a caloric deficit. However, this can also backfire if your exercise routine leaves you hungrier, so you unintentionally overeat calories due to increased hunger and cravings. Ketones have known appetite suppressing effects, so a ketogenic diet might help counteract any increased hunger that comes with exercise.
That said, I think the root of this question is the fact that ketosis is a fat-burning state, and so the logic goes that if you are metabolizing fat for energy, you will automatically shrink your body fat stores. Moreover, if you add keto and cardio together, especially if you are exercising in the so-called “fat-burning zone,” you will lose more fat than either alone. Right? Not necessarily. The fat you burn can come from your adipose tissue or from your plate. If you are eating an excess of fat calories relative to your daily caloric needs, you still won’t lose body fat.
We know that for body recomposition, the best bang for your buck comes from a combo of resistance training and HIIT. Cardio exercise still has many benefits for physical and mental health, and of course a lot of people simply enjoy their cardio; but you shouldn’t be putting all your eggs in the cardio basket if fat loss is your goal. All else being equal, though, it certainly can’t hurt to upregulate your body’s ability to use fat for energy.
When first starting out with keto, follow the recommendations laid out inThe Keto Reset Diet,and be strict forat leastthree weeks.
If you are struggling in your cardio workouts during this period, don’t add back carbs! Dial back your workouts, add calories (via fat or protein), or both.
Once you believe you are keto-adapted, then you can start to experiment with targeted carbs and/or carb ups if you so choose.
No matter your diet, avoid chronic cardio exercise patterns that increase stress and your body’s demand for glucose.
Check out this post for additional tips for exercising while keto.
Thanks, everyone. Questions, comments? Share them below, and have a good week.
Malhotra A, Noakes T, Phinney S. It is time to bust the myth of physical inactivity and obesity: you cannot outrun a bad diet. Br J Sports Med 2015;49:967-968. Matoulek M, Svobodova S, Vetrovska R, Stranska Z, Svacina S. Post-exercise changes of beta hydroxybutyrate as a predictor of weight changes. Physiol Res. 2014;63 Suppl 2:S321-5.
Newman JC, Verdin E. ?-hydroxybutyrate: much more than a metabolite. Diabetes Res Clin Pract. 2014;106(2):173-81.
Sleiman SF, Henry J, Al-Haddad R, et al. Exercise promotes the expression of brain derived neurotrophic factor (BDNF) through the action of the ketone body ?-hydroxybutyrate. Elife. 2016;5:e15092.
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Every man faces erectile dysfunction sooner or later. What happened? Correctly understand all the reasons can only competent specialist.
Impotence – shameful topic? NO!
Many men (if not most) sooner or later face a situation when at the moment of intimate closeness the penis suddenly refuses to come to a working state. When the first shock of failure passes, thinking begins – what was it? The partner has lost appeal? Or is there something wrong with health? Or maybe old age is already sneaking up? And most importantly, what to do now?
Erectile dysfunction question
As a rule, the man quickly goes to the last question, not finding the answers to all previous ones. And due to the sensitivity of the problem, he does not seek medical help, but begins to engage in amateur activities – to search for information of dubious quality on the Internet, to buy advertised drugs or dietary supplements with unknown contents, or to address psychics and magicians altogether.
Causes of Erectile Dysfunction
Such a course of action is fundamentally wrong. Not understanding the cause of erectile dysfunction (so correctly called impotence, both single and permanent), reliably cure it is impossible. At the same time, a long fixation on the problem will constantly reduce self-confidence, forming a “vicious circle” and leading to a further deterioration of potency.
There are many causes of erectile dysfunction (ED), so only a specialist can correctly understand what led to it. This does not apply, perhaps, only to those cases where a single erection disorder occurred due to fatigue or lack of sleep and after rest the working capacity of the sexual organ was fully restored.
Erectile dysfunction reasons
In the formation of ED, psychological factors often play a key role: experiences, nervous tension, stress, and more serious disorders such as phobias, anxiety, depression, and others. In such cases, the andrologist and the clinical psychologist should work together to help the patient.
Many drugs can also affect potency, as well as alcohol and other drugs. One of the key predisposing factors for ED is smoking. The features of lifestyle can also make a contribution: sedentary work, lack of physical and mental overload, food and wardrobe.
Sometimes the cause of impaired potency is unobvious factors, for example, ejaculation, increased arsenic in drinking water, physical effects (vibration, pressure, etc.), damage to the gums and periodontal and others. Impotence-proving diseases
In addition, ED may be the result of various diseases. They can be divided into two large groups. The first relate directly to the reproductive system – a lesion of the vascular system and the cavernous bodies of the penis, damage to its nerves as a result of inflammation, surgery or injury. This also includes some endocrine disorders – a violation of the production and metabolism of hormones that regulate sexual function.
Another group – systemic diseases that affect the body as a whole. These include diabetes, coronary heart disease, multiple sclerosis and many other chronic diseases. Age is also important – in the fifth ten the risk of ED is four times lower than in the seventh.
The findings suggest that rising rates of overweight and obesity worldwide about 1 billion people are projected to be obese by 2030 could lead to an increase in the number of cases of severe liver disease and cancer in the future, the researchers said.
Bernstein said the findings “highlight the importance of early intervention for this disorder to prevent significant liver disease which may occur decades in the future.”
Obesity, an abnormal medical condition, is becoming one of the most serious public health problems worldwide and its prevalence has dramatically increased in the last few decades. Obesity is defined as having a body mass index equal to or higher than 30 kg/m2. The marked increase in the worldwide incidence of obesity, particularly in children, has been noted by the World Health Organization.
Factors such as alcohol consumption and smoking by the men were taken into account and the researchers excluded men who received a diagnosis of alcoholic liver disease during follow-up from their analysis, but this did not significantly change their overall findings about excess risk associated with high BMI.
This was an observational study, so no firm conclusions can be drawn about cause and effect. However, the researchers said it was likely that the increased prevalence of overweight and obesity around the world could lead to an increase in the total number of cases with severe liver disease in the future, including an increasing incidence of liver cancer.