Tiny as they are, beans can help you feel energized and fuller longer than almost anything else you can eat. The reason is twofold: They're incredibly high in fiber, which swells in your stomach and promotes a feeling of fullness. And, they're stuffed with a highly complex form of carbohydrate that can take your body a long while to convert into energy. Like meat, they're also packed with protein. But unlike meat, they've got no saturated fats. "Beans of all types are always high on most nutritionists' lists," says Chicago-based nutritionist Jennifer R. Bathgate, R.D. So why'd our experts pick the black variety? Easy. Ounce for ounce, they have more fiber per serving than any other member of the legume family.