Protein is one of the macronutrients and most important sources of calories to be consumed at each meal, including snacks. Its power to slow digestion and regulate blood sugars, hunger, and energy levels can improve your productivity and performance — and you won't need to take so many coffee breaks. This is especially true during that afternoon drop, when many of us reach for a quick fix of processed foods or “empty calories.” Luckily, we have plenty of protein sources from plants, animals, and dairy products to save us from malnutrition and help us reach our potential.