Photo Credit: by Kristina Compbell
"Eat meat. Not too little. Mostly fat." Such is the guideline of one devotee of the ketogenic diet—a way of eating that focuses on foods high in fat and low in carbohydrates.
In a world of trendy low-carb diets, the ketogenic version of low-carb is particularly extreme. It prescribes the avoidance of all sugary foods, grains, fruits, and legumes, and allows fat- and protein-rich foods like meat, fish, eggs, cream and butter, as well as nuts and seeds and a few low-carbohydrate vegetables. This is the dietary pattern that permits a burger topped with cheese and bacon and a fried egg. No bun, of course.
The ketogenic diet, while commonly claimed to induce weight loss, is not necessarily a low-calorie diet. Its severe restriction of carbohydrates, however, makes the body shift into a state where it’s necessary to burn fat for energy. This serves to increase the production of ketones—the residues left behind when fats are burned without sufficient glucose.
There’s one big problem, though: the diet seems to fly in the face of nearly all the dietary recommendations around the world. These recommendations, developed by experts based on decades and decades of nutritional research, advise the consumption of less meat and fat, not more. Total fat intake in particular is linked with cardiovascular disease risk.
So what’s the big deal about the ketogenic diet? The scant evidence that exists on its health effects seems to show the diet doesn’t have much of an effect on regular people, especially in the short term. One study found modest weight loss and a slight decrease in physical performance (for example, slightly faster exhaustion) in healthy adults who adopted the ketogenic diet for 6 weeks.
But could the diet have therapeutic promise for people with certain health conditions? Here, the evidence is stronger. Several studies suggest the diet improves insulin sensitivity in those with diabetes. But most of the scientifically-backed benefits of the diet revolve around the brain.
Reportedly, the diet was designed in the first place by a Mayo Clinic doctor in the early 1920s as a treatment for epilepsy (and was highly preferable to the practice of starving children with epilepsy for up to 25 days in order to control their seizures). Pediatric epilepsy does seem to be a condition for which the diet is useful: a long-term study of 150 children found that, after 3 to 6 years on the ketogenic diet, their difficult-to-control seizures had gotten better and many were able to decrease or discontinue their medicine. And despite eating so much fat on a daily basis, these children had no apparent cardiac complications.
The ketogenic diet shows promise for other brain conditions, too. In one recent study, researchers looked at brain energy metabolism in a group of people with Alzheimer's disease (AD) and another group with mild cognitive impairment (MCI); both of these groups were compared with healthy individuals of the same age. The researchers found the differences in brain energy metabolism in those with AD and MCI that specifically had to do with glucose. Although it wasn't clear whether this metabolic difference was a cause or an effect of the cognitive impairments, the researchers surmised that a ketogenic intervention might have the possibility of correcting brain metabolism in AD and MCI.
The bacteria living in the human digestive tract—which are known to respond to diet, and also reveal clues about health—might in future provide more information about the positive or negative effects of the ketogenic diet. A small study of people with multiple sclerosis, for instance, found that after starting on a ketogenic diet, individuals' gut bacterial diversity initially decreased, but then started to increase again after 6 months on the diet. The researchers didn’t track the effects on health, but greater diversity is usually associated with better health outcomes.
Maybe the ketogenic diet is a big fat deal for good reason, but that doesn’t mean it’s for everyone. Diet and health—especially brain health—is complex, and it’ll be many more years before scientists know exactly who should go keto for life.
###
Kristina Campbell is a freelance science writer specializing in the gut microbiota and digestive health.
Your email address will not be published. Required fields are marked with *.