The Ornish Diet is a vegetarian diet that is very low fat. While fat is often what satisfies us, this diet eliminates almost all meats, nuts, and oils. Instead, you get to eat a nearly unlimited amount of whole grains, vegetable, and fruit. This is a great diet for those who like to eat large quantities, as most of what you eat will be low in calories and allow you fill up your plates. However, you still need to eliminate processed carbohydrates while on the Ornish Diet. The following foods are not allowed: oils, sugar, white rice, and white sugar.