Lean protein fills you up faster than other types of foods, but there’s more reason than that to choose this as your go-to food. Compared to other macronutrients, your body uses almost twice as much energy to break down and convert protein to fuel. In fact, a protein-based meal elicits a thermic effect of close to 30 percent of the total calories consumed—meaning that 600 calories of food burns up 180 calories just to eat!