Keto Diet Downsides May Outweigh Benefits: Review

If you’ve been weighing the pros and cons of the ketogenic diet, one of the most fiercely debated eating plans, a new review suggests the downsides may eclipse the benefits.

The analysis, published in the July 2021 issue of Frontiers in Nutrition, examines the potential long-term risks of the keto diet, which is a very low-carb, high-fat style of eating. People on this restrictive diet typically get 70 to 80 percent of their daily calories from fat, 5 to 10 percent from carbohydrates, and 10 to 20 percent from protein, according to the Harvard T.H. Chan School of Public Health. (The U.S. Department of Agriculture’s Dietary Guidelines for Americans say most people should get 20 to 35 percent of their daily calories from fat, 45 to 65 percent from carbs, and 10 to 35 percent from protein.)

The new review examined more than 120 studies, says one of its authors, Neal Barnard, MD, of Washington, DC, the president of the Physicians Committee for Responsible Medicine. The PCRM is a nonprofit that promotes a plant-based diet, which is essentially the opposite of the meat-heavy keto diet.

“There have been a great many hints about the risks of ketogenic diets for a long time, and this review really brings the evidence that the ketogenic diet, for some people, causes weight loss,” Dr. Barnard says. “But even when it does, the risks greatly outweigh any benefit — and the weight-loss benefits are short-lived for most people, anyway.”