Try to eat at least 1 gram of protein for each pound that you weigh (For example, a 160 lber would eat 160 grams of protein) every day. I mainly try to eat foods that are high in protein and low in simple sugars. Some examples of foods that are great for muscle building are tuna, chicken, peanut butter, oats, milk, and eggs. There’s nothing wrong with having a snack or a cheat meal every now and then (genetics pending).