Protein helps with weight loss in a number of ways. (Use these tricks to eat more healthy protein without even trying.) First, your body uses more energy—think calories—to break down protein foods than it does to break down other foods. Protein also helps you hang onto muscle mass as you’re losing weight, and since muscle burns more calories than fat, you want to keep as much of it as you can. Finally, protein dampens hunger better than carbohydrates do, says Donald K. Layman, PhD, the Journal of Nutrition study’s lead researcher, adding that decreasing carbohydrates also helped the protein group lose weight.