Protein is the all-mighty macro that feeds your muscles to help them grow bigger and stronger, curbs hunger, lowers blood pressure, boosts metabolism—more. But to say any protein-rich food can get you these benefits is flat-out wrong. There are optimal sources of protein, just as there are optimal food sources of fat, carbs, and sugar.
"High-quality protein refers to sources that are highly digestible and contain all the essential amino acids your body needs to build and maintain muscle mass, manage weight, and support a number of functions and structures in your body," says Jordan Mazur, MS, RD, director of sports nutrition at the University of California, Berkeley. "The following foods provide a decent amount of protein, however they may not be complete protein sources or aren’t the health foods that contribute to overall well-being and fitness." And that's being democratic about it; limit your consumption of these poor-quality foods or your health (and gut) will surely suffer.