Ketogenic Diet – The BARMER's Take
BARMER (a health insurance organization in Germany) has published an article on the ketogenic diet (page in German). It is remarkably measured for an article that ultimately steers readers away from trying ketogenic eating for themselves. The author(1) has evidently researched thoroughly, cited thoroughly, and thoroughly missed what her own arguments are actually saying.
I have been eating ketogenically for almost 14 years. Not as a diet - diets end at some point. As a way of living. In that time I have read many articles on “the keto diet”, and the BARMER’s is among the better ones. What makes it interesting: read it carefully enough, and you may reach different conclusions than the author did, with her own arguments.
I’d like to comment on a few highlights. Each section also links to other articles for anyone who wants to dig deeper.
Origins in 1921 – or: Every Baby Is a Proto-Keto Enthusiast
“The ketogenic diet has its origins in 1921…”
No.
It may have received its medical name in 1921. Its origins go back to birth: a healthy newborn enters the world in ketosis. Breastfed infants remain in this state for the most part (2). It only ends with the first spoonful of fruit purée, mashed potato, rusk, or sweetened formula.
One could put it this way: ketogenic eating is the default state. The question isn’t how long you can sustain it: The question is why you ever left it.
“Alternative” Energy Source – Who’s Really the Alternative Here?
“It produces ketones and uses these as an alternative energy source instead of glucose.”
That phrasing is revealing. Ketones as an alternative to glucose.
Homo sapiens has existed for roughly 300,000 years. Agriculture dates back some 10,000 years. Carbohydrates in the quantities we now consider normal - enough to keep us permanently out of ketosis - have only been universally available since industrialisation, roughly 200 years ago. One could argue that it isn’t ketones that are the alternative, but glucose.(3)
But fair enough - it’s a matter of perspective.
The DGE Says: 50 Percent Carbohydrates. For the Healthy.
“The DGE recommends that healthy people take in at least 50 percent of their daily energy in the form of carbohydrates.”
For the healthy. That little qualifier carries a lot of weight. It implies - without saying so - that the recommendation doesn’t apply to the unwell. For people with insulin resistance, metabolic syndrome, type 2 diabetes, epilepsy? What applies to them?
Interesting side note: ketogenic eating has been a standard clinical tool in paediatric epilepsy for over a century — in people who are emphatically not healthy, and for years at a time (4). The question there is ‘does it work?’ The answer is an unambiguous yes. That means the argument against it for healthy adults has to be something stronger than: ‘you don’t need it to work’.
Nutrient Deficiencies: A Warning in Search of Its Symptoms
“Scientists from the DGE explain that a severe restriction of food choices increases the risk of nutrient deficiencies.”
After almost 14 years, I’m still waiting for my first deficiency symptom. That is, admittedly, not scientific proof - I am one data point, not a study design. But a stubbornly healthy one.
Let me pick one common example:
Just as vegans are always first asked about vitamin B12, I tend to get asked about vitamin C when I mention I don’t eat fruit. What most people don’t know: Vitamin C and glucose compete for the same transport mechanism (5). Without dietary carbohydrates, the receptors for vitamin C are considerably less “blocked” and can absorb it even from small amounts. Scurvy (the vitamin C deficiency disease) historically struck a ships’ crew who lived mainly on hardtack - not the officers, who also ate meat (6).
Protein as an Energy Source: A Persistent Misconception
“Anyone who drastically reduces the carbohydrate portion of their diet needs alternative energy sources: protein and fat.”
Wrong - at least in the context of ketogenic eating. In ketosis, protein is not used primarily as an energy source. Energy comes from fat. Protein serves to maintain muscle mass and body structure - as it always does.
Confusing “high-protein” with “ketogenic” is one of the most common errors in articles on this topic. A ketogenic diet is high in fat, moderate in protein, and low in carbohydrates. Not “lots of meat and even more steak”. Even if the potential for drama there would be considerably greater (7).
Saturated Fat and the Legacy of Ancel Keys
“Saturated fatty acids are associated with an increased risk of cardiovascular disease.”
This claim originates largely from the 1950s and the work of Ancel Keys. His Seven Countries Study was methodologically… let’s say: selective. To cut a long story (very) short: Before starting to work on his Seven Countries Study, he published data from 6 countries that showed a clear correlation between saturated fat intake and coronary heart disease. The problem: He had data from 22 countries and chose to present the six that supported his hypothesis, omitting the others (8). Following this, the choice of the countries for his Seven-Countries-Study was never laid out convincingly.
More recent meta-analyses find no significant association between the consumption of saturated fatty acids and heart disease (9). The old hypothesis prevailed because it prevailed (!) - not because the evidence was overwhelming.
The article therefore recommends plant oils instead. Of all things, the polyunsaturated fatty acids in plant oils are chemically far less stable and oxidise when heated. I personally avoid them strictly. But that’s another story.
Wholegrains and Zinc – or: What Phytic Acid Has to Say About That
“Wholegrain products supply anti-inflammatory nutrients such as zinc. […] quality and adequate quantity are, however, what matter.”
True. Wholegrains contain zinc. What wholegrains also contain: phytic acid - an antinutrient that binds zinc and significantly reduces its absorption in the gut.(10) What dramatically improves absorption, on the other hand: animal proteins, particularly histidine and cysteine, which form soluble zinc complexes. Someone who eats meat absorbs more zinc from a smaller source than someone eating wholegrains.
The reassuring closing phrase (“quality and adequate quantity”) sounds reassuring but says absolutely nothing. Quality in what dimension? Bioavailability? Chemical binding? Necessary cofactors? Free of mold? How much, or how little? All of that is left as an exercise for the reader (11). Classic hedging.
Missing Long-Term Studies
The article laments the lack of long-term studies. That’s true - for the formal clinical literature.
But one could also argue that 300,000 years of human history constitute a kind of long-term study - with a control group that subsisted largely on what it could hunt and gather, and little of what now forms the base of the food pyramid.
The question is which null hypothesis you apply.
And returning to plant oils, which the author, like so many in the nutrition industry, seems to prefer: I find myself missing the long-term studies on their safety. Most seed oils have only been in use in this form for 50–100 years, and, remarkably, we have been getting progressively sicker ever since.
Conclusion
The article was a pleasure to read for its composure, but presented me with nothing new - at least given everything I’ve read on the subject so far. The arguments against ketogenic eating (here: diet) are the usual ones - exactly the ones I started this site to address, sorting and presenting all my thoughts and experiences.
In this case, my conclusion is: it don’t really need counter-arguing or a rebuttal. It’s enough to now read the same article a second time - from a new perspective.
