I’m not much one for dogmatic thinking or proselytizing when it comes to diets. I believe there are many different dietary patterns shown to promote good health, and different patterns work best for different people. I counsel patients on a variety of diets — from very low-fat Ornish-style diets for heart health to relatively higher-fat Mediterranean diets. I’ve got patients maintaining good health on high-carb vegan diets, moderate-carb paleo-style diets and lower-carb South Beach diets. You prefer not to eat gluten or dairy? Be my guest; we’ll work around it. From my perspective, what determines the healthfulness of a diet isn’t what you avoid, but rather what you actually eat.
[See: U.S. News’ 40 Best Diets Overall.]
But as live-and-let-live as I am when it comes to differing dietary philosophies, there is one increasingly popular diet fad that I cannot get behind: the ketogenic diet.
In case you haven’t yet heard about it, the ketogenic diet is an extremely low-carb, high-fat diet that was developed about 100 years ago as a veritable “metabolic hack” for people with epilepsy. The diet involves consuming about 70 to 80 percent of calories from fat, 5 to 10 percent from carbohydrates and 10 to 20 percent from protein. By way of comparison, a more typical range of fat intake would be 10 percent on a very low-fat diet to about 40 percent on a Mediterranean-style diet. A more typical range of carbohydrate intake would be about 30 percent on a lower-carb South Beach or Zone diet-type eating plan to 50 to 60 percent on your standard American diet.
By restricting almost all carbohydrate intake and even limiting protein intake, the ketogenic diet forces your liver to start producing substances called ketone bodies to supply the brain and body with the energy it needs to function. In so doing, researchers discovered, people with epilepsy were experiencing fewer and less severe seizures — and many were becoming completely symptom-free. In some cases, people with epilepsy remained symptom-free for prolonged periods — even after going off the diet, so long as they initially stayed on it for a period of several months to a few years. Before the advent of newer medications for epilepsy, the ketogenic diet was considered one of the most effective treatments available.
Given its history, virtually all the research into the health effects of the ketogenic diet has been conducted on people with epilepsy, particularly children. In this population, gastrointestinal tolerance issues like constipation, diarrhea and nausea are among the most common side effects of the diet. But some of the more serious risks associated with longer-term ketogenic diets include hypothyroidism, reduced bone mineral density, kidney stones and gallstones. For a child with severe epilepsy, however, these health risks were often deemed acceptable when compared to the benefits of reducing or even eradicating seizures.
[See: 8 Food Trends Nutrition Experts Pray Will Never Return.]
Today, the ketogenic diet is enjoying another 15 minutes of fame among otherwise healthy people. Fans of the diet report benefits including weight loss, blood sugar and hunger control, and mental clarity. But little is known about the long-term consequences of following a ketogenic diet among generally healthy people.
Based on what we know from the studies in people with epilepsy, coupled with what we know about dietary patterns and other health risks, though, I’m hereby waving a giant red flag. You may very well feel energetic on the ketogenic diet and love how it helps you lose weight. You may even have figured out to manage the bad breath or raging constipation induced by this diet so that these common side effects are livable. But I urge my patients considering this diet to think about the potential impact it may have on gut health. For example:
Digestive System Cancer Risk: This is one of my chief concerns regarding the ketogenic diet. The evidence is quite strong as to what dietary patterns are associated with increased risk of developing digestive system cancers — including and especially colon cancer — and what patterns are protective against them. The ketogenic diet is a textbook example of a high-cancer-risk dietary pattern: very high in animal fat in general and red meat in particular, and very low in fiber-rich fruits, vegetables, beans and whole grains. Colon cancer is the second leading cause of cancer deaths among Americans, and death rates have been sharply increasing among young people ages 20 to 50 in the past 20 years. Colon cancer is not just something that happens to grandparents; it increasingly affects their millennial grandchildren as well.
Likely Devastation of the Gut Microbiota: As health researchers uncover more and more connections between the inner ecosystem of our gut’s microorganisms and health conditions ranging from obesity and autoimmune disease to depression and eating disorders, one thing is becoming increasingly clear: A very diverse, thriving inner ecosystem is associated with better health outcomes across the board. Researchers have also found that there’s really only one surefire way to cultivate a diverse, robust inner ecosystem: by consuming a high-fiber diet composed of a variety of different plant-based foods — from leaves and roots to fruits and flowers, whole-cereal grains and legumes to nuts and seeds. This is because a diet that’s diverse in fiber types will feed and nurture a diverse community of microbial species.
[See: 7 Reasons to Choose a Plant-Based Diet.]
Conversely, a very low-carb, low-fiber diet that’s heavily weighted to fat and animal protein has been shown to reduce the diversity of your gut microbiota — and such changes can happen quickly in response to a dramatic diet change. A typical ketogenic diet is likely to essentially starve many of the health-promoting species that produce metabolic byproducts called short-chain fatty acids, and selectively nourish other species whose predominance is associated with obesity risk and inflammatory disease. Short-chain fatty acids help protect your gut’s mucus barrier — an essential component of the immune system — but these important compounds are very diminished in the guts of people following a high-fat, low-fiber diet like the ketogenic diet.
When selecting a dietary pattern, it’s important to remember you’re not just eating for one; you’re eating for 100 trillion. Your food choices may have consequences beyond the narrow measure of what you see on the scale today, and following the ketogenic diet may be missing the forest for the trees.
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No One Diet Is Right for Everyone, but the Ketogenic Diet Is Wrong originally appeared on usnews.com
