Our modern diet, saturated with carbohydrates, has become the leading cause of death worldwide. Faced with the explosion of metabolic, cardiovascular, and neurodegenerative diseases, many experts are sounding the alarm. Among them, Dr. Boris Dufournet, a neurologist specializing in the ketogenic diet, proposes a radical paradigm shift: a return to a diet physiologically suited to our species. Far from fleeting nutritional fads, this is a biological necessity grounded in millions of years of evolution.
Human evolution: carnivores or vegetarians?
To understand what we should eat, it is essential to turn to paleoanthropology. The species Homo sapiens has existed for approximately 300,000 years, and the genus Homo for nearly 3 million years. During this immense period, our genetics have not fundamentally changed, unlike our environment.
Isotopic analyses (particularly nitrogen-15 concentration) performed on the bones of our ancestors are conclusive: the degree of carnivorism of early humans was equivalent to that of modern wolves or hyenas. Humans began as opportunistic scavengers, which explains the extreme acidity of our stomachs (with a pH between 1.5 and 2, very close to that of a vulture), before becoming formidable predators.
The idea that our distant ancestors primarily consumed plants is a paleoclimatological fallacy. During glacial periods, abundant vegetation did not exist. Today, field paleoanthropologists agree that humans are obligate carnivores and facultative omnivores .
The ravages of hyperinsulinism and carbohydrate toxicity
The widespread introduction of carbohydrates into our diet is very recent on a human timescale. Cereal consumption truly began only a few thousand years ago (notably in Mesopotamia and ancient Egypt), which also led to the appearance of the first documented cases of diabetes and bone tuberculosis linked to a decline in immunity.
Today, excess carbohydrates cause major damage through a primary mechanism: hyperinsulinism . Contrary to popular belief, insulin is not just a blood sugar-lowering hormone; it is primarily an anabolic hormone (growth factor). Faced with a massive influx of sugar, the body secretes enormous quantities of insulin to eliminate this glucose, which is toxic to the blood. Eventually, this mechanism breaks down.
Insulin resistance: To protect themselves from this chronic hormonal excess, cells suppress their insulin receptors. The pancreas then has to produce even more insulin, creating a vicious cycle leading to type 2 diabetes and fat storage (hepatic steatosis or “fatty liver”).
Cell proliferation: Tissues that cannot develop insulin resistance are severely affected by its anabolic effect. This is the case with arteries. Atherosclerosis is not simply a deposit of cholesterol, but a thickening and proliferation of cells in the arterial wall under the influence of insulin.
The brain in danger: Alzheimer’s and neurotoxicity
Neurologically, the impact of carbohydrates is devastating. Certain areas of the brain, such as the hippocampus (the seat of memory), are highly dependent on insulin. When they become resistant to insulin, they enter a state of shock, leading to the memory loss typical of Alzheimer’s disease.
Furthermore, the brain undergoes what researchers call ketosuppression . Our nerve cells are designed to function optimally with ketone bodies (derived from fats). By constantly consuming carbohydrates, we block the production of these ketones, forcing the brain to run exclusively on glucose, an emergency fuel that generates significant oxidative stress.
The true ketogenic diet: a biological definition
The ketogenic diet is often misunderstood. It is not defined by a precise ratio of macronutrients on the plate, but by a biological state: the significant presence of ketone bodies in the blood (generally between 1.0 and 3.0 mmol/L in the morning on an empty stomach).
This state of ketosis is our default metabolism. Babies are born in ketosis and remain there during the breastfeeding period, because this metabolism provides clean and abundant energy, essential for brain development.
In practice: the “Keto Carni Flex” (KCF) approach
To regain metabolic health, Dr. Dufournet recommends an approach called “Keto Carni Flex,” which aims to be paleo-consistent:
The meat base
The diet should be based on raw animal products, primarily from ruminants (beef, mutton, lamb, goat). It is crucial to rediscover less expensive cuts and especially offal, which are true superfoods:
