The ketogenic diet is a very low carb, high fat diet that shares many similarities with the Atkins and low carb diets. It involves drastically reducing carbohydrate intake and replacing it with fat. This reduction in carbs puts your body into a metabolic state called ketosis. A healthy keto diet is built on whole, nutrient-dense foods, such as meat, fish, eggs, and non-starchy vegetables, along with natural fats like butter or olive oil.