Eating an appetizer of a broth-based soup or even an apple can reduce total calorie intake over the course of meal by up to 20 percent,according to a series of "Volumetrics" studies at Penn State. Consider that,according to the Journal of the American Medical Association,the average restaurant meal contains 1,128 calories.A 20 percent savings, just once a day, is enough to help you shed more than 23 pounds in a year.