The ketogenic diet was originally designed in 1923 by physician Russell Wilder as an effective treatment for epilepsy.

Several variations of the keto diet exist today, but generally, it’s a very low-carbohydrate diet (VLCD) featuring a moderate amount of protein, high amounts of fat and no more than 5% to 10% of one’s daily calories from carbohydrates. Someone following a 2,000-calorie diet can consume no more than 200 calories—or 50 grams—of carbohydrates a day on the keto diet.