Recently, as part of what is somewhat of a general cycle of push and shove in terms of macronutrient preferences among diet trends, the “ketogenic diet” has become hugely popular. This diet is essentially ultra low carb, with the specific goal of reaching a state of metabolic ketosis and achieving a slurry of metabolic benefits (in reality there is little difference* with past ultra low carb/paleo diets in terms of content, rather the goal is just described differently). The diet has notably been present in the medical literature for awhile as a therapy for severe epilepsy (via reducing glucose utilization in the brain).
Purported benefits of a state of ketosis include most notably:
- Large increases in insulin sensitivity/reduced blood sugar.
- Increased mental focus/decreased anxiety.
- Reduced hunger.
- Improved skin quality/reduced acne.
- Reduction in rates of insulinemic/age associated diseases.
Side effects are mild in theory and include particularly diuresis associated symptoms (cramps, constipation), hunger and reduced performance initially. Additionally, the diet usually includes meat but is not too hard for vegetarians (though if you don’t eat soy or dairy it may be significantly more difficult). The following websites/articles are good resources for those interested in trying to achieve nutritional ketosis:
My initial experience with keto was too dive in with a 3 day, fully no carb fast after reading about it from a Tim Ferriss book. I have been doing 8 hour window intermittent fasting for several years (https://leangains.com/the-leangains-guide/ ) and had done a few full day fasts, so the idea of dealing with hunger was not new to me. However, my experience by the end of the 2nd day was amazing:
- No weakness/confusion like with full, day long fasting.
- Absurd levels of mental focus/mental and physical energy.
- A total lack of anxiety.
- Limited, intermittent hunger and a general feeling of well being.
I suspect that, though I really dived into it, many people who switch to the diet are convinced by the same kind of super human feelings I started with. However, I was really sold by some of the scientific literature purporting to show a significant reduction of age related decline in mice put on a ketogenic diet, particularly this one:
Thus I switched to a ketogenic/8 hour IF diet with under 30g carbs centered around exercise on weekdays, and standard diet during the weekends.
I saw an initial 6lb weight loss and a definite, low level continued reduction in baseline anxiety and mental hyperexcitability. However, the superman effects I started on did not persist overall, and I also felt somewhat less mentally creative and lacking in mental energy when acutely ketogenic. However, I continued until 1 day I stepped on the scale to weigh myself after 6 months and I had gained 20lbs! Though some of this was likely muscle due to simultaneously increasing my lifting when starting keto, a large % of it was clearly visceral fat.
Why would keto increase visceral fat? 1 potential reason is that carbohydrates generally reduce cortisol, a stress hormone which promotes visceral fat storage. But either way, I delved back into the literature and realized several key things.
1)The Ketogenic Diets initial effects are deceptive
The initial superman buzz I felt when delving into ketosis was in some ways not unlike any other day spent fasting. In general, fasting leaves people feeling mentally and physically better, and that’s why they do it. However, in this case I ate protein, which largely alleviates the concurrent weakness and mental lethargy observable in an acute starvation response. Additionally, my quick dive into keto likely was exacerbated by being unprepared to metabolize fat as a primary energy source, meaning I was essentially eating and feeling mentally happy that I had a meal without really being able to fully utilize the calories. Lastly, the 6lb loss initially was likely water weight due to the diuresis effect (it was a rapid loss and promptly stopped at 6 lbs).
One things is certainly real: the determination to stop eating carbs definitely enabled me to reduce calorie load overall. Carbs are addictive, probably more so than fat, and people who go out of their way to get on diets and lose weight are likely even more addicted to them than the average person. This leads to my second point:
2) Case or small population studies on dieters are deceptive
Studies and case stories in people lack a calorie matched, low fat control, and generally are done in people who have a high simple carbohydrate content in their diet in the first place (i.e. “western diet”). In an ideal context, someone would compare an intermittent fasting, high slow carb group to a ketogenic diet group, except that won’t happen because compliance would be too low. Additionally, they generally look at changes of disease biomarkers in a short term context, whereas a multiyear study would be more appropriate
Studies in mice, first of all, are in mice. Mice tend to die of cancer at a much higher rate than humans, and a potential benefit of low sugar towards cancer risk would have disproportionate effects. Additionally, they are somewhat contradictory: Two studies (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4371964/ , https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5087279/ ) suggest that high carbohydrate ratios in the diet are actually preventative of age related disease**.
3) Long lived populations do not exclude carbohydrates from their diet
A final point is that we do have long term, population wide studies on populations who have exceptional longevity. The Okinawans, famously known for having a very high percentage of centenarians (over a century old) among their population, have a very high carbohydrate, high vegetable, low protein, low fat, and low sugar diet:
Additionally, other long lived Asian centenarian groups have similar features:
And lastly, another long lived area, Ikaria in Greece, is not particularly low in carbs (though includes a lot of olive oil).
Population studies like this are mired by 2 difficulties: the influence of genetics and the influence of lifestyle. Though I’m sure lifestyle plays a factor, it’s notable on the genetics side of the argument that the Okinawan diet has westernized over the last few decades and this has resulted in a loss of the observed lifespan effects.
On the flipside, I had heard the argument on several occasions that two populations with low fat diets, Inuit and Masai, have very low rates of heart disease and insulin associated disease. However, this seems to be above all an unsupported rumor, and this article points out a lot of the contradictory information: https://nutritionstudies.org/masai-and-inuit-high-protein-diets-a-closer-look/
Above all else, this experience has taught me to distrust anecdotal evidence associated with dieting and to reject the red pill mindset people have about lifestyle changes. There is definitely supportive evidence for the ketogenic diet, and perhaps it works well for some people. I can even say it definitely increased focus in my experience. However, in the end many factors add together to shift people towards preference for extreme ideas because they see some positive effects.
Also, for a similar, well written argument against low carb dieting, check this article out: https://leangains.com/low-carb-talibans/
*there are a few notable differences, including the addition of MCT oil/beta-hydroxybutyrate among serious followers to promote ketosis more easily).
**to be fair, they compared carbohydrates to protein, and largely ignored fat intake.