Athletes taking protein might get stronger, but it could just be because they're eating more total calories — not because of the protein itself.

Protein supplements might give athletes a small boost in endurance, especially when taken with carbs—but it could just be because they're eating more calories overall.

Taking about an extra gram of protein per pound of body weight every day — mostly from supplements — might help athletes perform their best, but it's hard to be sure because most studies don’t account for total calories.

Taking protein supplements for several weeks might help athletes perform better than taking them just once, but we’re not totally sure because the studies didn’t control for total calorie intake.

If you lift weights and eat lots of protein, you’ll likely build more muscle and get stronger than if you just do one or the other—because together, they work better than alone.

If two people eat the same total amount of protein each day, it doesn’t matter whether one drinks a protein shake after the gym and the other drinks it at breakfast—both will gain muscle and strength about the same, but there’s not much research on this yet.