Fad diets such as a meat and fruit diet are meant to encourage short-term weight loss, and they can be successful. However, there are potential risks to eating. A diet consisting of lean protein, fresh fruits and vegetables mimics the diets of our ancient ancestors and, proponents believe, best suits our genetics. This is a detailed beginner's guide to the paleo diet. Eat: Meat, fish, eggs, vegetables, fruits, nuts, seeds, herbs, spices, healthy fats and oils.