LeannX Keto The keto diet limits starchy vegetables such as carrots, sweet potatoes, parsnips, pumpkin and squash and eliminates many fruits. LeannX Keto Reviews For our bodies, a ketogenic diet is actually a partial fast. During a total fast or starvation state, the body has no source of energy. With the keto diet, the ketones provide an alternative source of energy. Unlike a full fast, the keto diet helps to maintain lean muscle mass. Without enough carbs for energy, the body breaks down fat into ketones.