A deficiency in protein leads to muscle atrophy and impaired functioning of the human body in general. High protein foods include meat, fish, cheese, tofu, beans, lentils, yogurt, eggs, nuts, and seeds. Below is a list of foods with the highest protein to calorie ratio, for more information, see the sections on protein dense foods, other protein rich foods, low calorie high protein snacks, and protein isolates. Protein in 100g.