There is no universal definition of a low-carb diet. The number of carbohydrates permitted on a low-carb diet depends on the specific meal plan. The keto diet, for example, is a variation of a very low-carb diet that typically recommends 20 to 50 grams of carbohydrates per day. Some evidence suggests that a low carbohydrate diet may be defined as less than 130 grams per day, or 26% of total energy intake.