The gist of the eating plan? Taking in so few carbs sends your body into ketosis—a state of burning fat for energy, instead of carbohydrates or sugars, explains Beth Warren, RDN, founder of Beth Warren Nutrition and author of Secrets of a Kosher Girl: A 21-Day Nourishing Plan to Lose Weight and Feel Great (Even If You're Not Jewish). In order to stay in ketosis, you only consume 5% to 10% of your calories from carbohydrates—which for most followers is fewer than 20 grams total per day—and instead eat moderate amounts of protein and high amounts of fat.
Some research suggests that ketogenic diets might help lower your risk of heart disease. Other studies show specific very-low-carb diets help people with metabolic syndrome, insulin resistance, and type 2 diabetes. Researchers are also studying the effects of these diets on acne, cancer, polycystic ovary syndrome (PCOS), and nervous system diseases like Alzheimer's, Parkinson's, and Lou Gehrig's disease.
There are three instances where there’s research to back up a ketogenic diet, including to help control type 2 diabetes, as part of epilepsy treatment, or for weight loss, says Mattinson. “In terms of diabetes, there is some promising research showing that the ketogenic diet may improve glycemic control. It may cause a reduction in A1C — a key test for diabetes that measures a person’s average blood sugar control over two to three months — something that may help you reduce medication use,” she says.