Eat 18 ounces a day and you can drop a jeans size. People who ate that much -- in conjunction with cutting their total calories -- lost 22 percent more weight and 81 percent more belly fat than dieters who skipped the snack, according to research from the University of Tennessee, Knoxville. They also retained one-third more calorie-torching lean muscle mass, which can help you maintain weight loss. "Fat around your waist produces the hormone cortisol, which tells your body to accumulate even more belly flab," says nutrition professor and lead study author Michael Zemel, PhD. When you eat yogurt, the calcium signals your fat cells to pump out less cortisol, making it easier for you to drop pounds, while the amino acids help burn fat.