These delicious and versatile nuts contain filling protein and fiber, not to mention vitamin E, a powerful antioxidant. They're also a good source of magnesium, a mineral your body must have in order to produce energy, build and maintain muscle tissue, and regulate blood sugar. "A stable blood-sugar level helps prevent cravings that can lead to overeating and weight gain," says David Katz, MD, a professor at the Yale University School of Medicine. But what makes almonds most interesting is their ability to block calories. Research indicates that the composition of their cell walls may help reduce the absorption of all of their fat, making them an extra-lean nut.