Keto and Mediterranean diets are good for controlling blood glucose levels and aiding weight loss

Reviewed by Emily Henderson, B.Sc.Jul 20 2022

A low-carbohydrate diet is generally recommended for people who have Type 2 diabetes or who are at risk of developing the disease. But there isn't wide agreement on how low to go in carbohydrate consumption or which carbohydrate foods to include, and little research is available to help people make informed decisions.

A new trial by investigators at Stanford Medicine has compared two popular low-carb diets — ketogenic and Mediterranean — in their effect on blood glucose, cardiometabolic risk factors, weight loss and nutrition, as well as how easily people can adhere to them.

The ketogenic diet is an ultra-low-carb, very high-fat diet that involves a drastic reduction in carbohydrate intake. The Mediterranean diet is a low-carb, moderately high-fat diet that emphasizes vegetables, legumes, fruits, whole grains, olive oil and fish.

Both diets received high marks in controlling blood glucose levels and aiding weight loss, but the ketogenic diet was lower in several nutrients, particularly fiber, and was more difficult for study participants to follow in the long run, according to findings published May 31 in the American Journal of Clinical Nutrition.

Low-carb diets for diabetes

The main issue in diabetes is the inability to manage your blood glucose, and the biggest effect on your blood glucose is your diet."

Christopher Gardner, PhD, the Rehnborg Farquhar Professor, professor of medicine and the director of nutrition at the Stanford Prevention Research Center, lead author of the study

Americans get roughly half their daily calories from carbohydrates, with about 80% of those carb calories coming from added sugars and refined grains — think soda, candies, bagels, pastries and pizza crust.

To manage or prevent diabetes, the American Diabetes Association recommends the Mediterranean diet and other low-carb diets, as long as they minimize added sugars and refined grains and include non-starchy vegetables.

The ultra-low-carb ketogenic diet fulfills these criteria. But its dramatic rise in popularity in recent years has nutritionists like Gardner concerned.