Ketogenic Diet
A diet involving the restriction of carbohydrates to the point of inducing ketosis (buildup of significant levels of ketones in the bloodstream). Usually this requires keeping carbohydrate consumption below 20 grams per day. Ketosis reduces appetite and some studies (but not all) have shown ketogenic dieters to lose relatively more fat and less lean body mass than non-ketogenic dieters. Note, however, that ketogenic diets are not usually well-suited for actually gaining muscle.