You probably associate high-protein eating with people trying to gain mass. And that's because it works! Diets that are rich in high-protein foods, in combination with resistance training, have been shown repeatedly to help athletes add or retain lean mass.
However, diets that include moderate or high-protein foods have plenty of other advantages. For one, as Jose Antonio, Ph.D., writes in the article "3 Myths about High-Protein Diets Debunked," "It's very difficult to get fat if the only thing you overfeed on is protein."
Most high-protein foods are themselves very low in fat and carbs. Chicken breasts have 2-3 grams of fat per serving, while cottage cheese has only 1-2 grams. Egg whites and fish are virtually fat-free, and in the case of fish, the fats they contain are often healthy omega-3 fatty acids.
High-protein diets can also help you lose unwanted weight. "Not only will this extra protein help you build more lean muscle mass, but it will also diminish your appetite, making you less apt to cave in to cravings," says Jose Antonio, Ph.D. "[It] can help you lose weight because of its ability to act as a potent thermogenic agent. That means your body burns more calories digesting protein foods than it takes to digest an identical amount of carbohydrate and fat."