These vegetarian and vegan sources of protein are alternatives that you can include in your diet. First up is tofu. It is a whole source of protein. You can stir fry it or add some to your salad. Next, Green peas! They're rich in leucine, an amino acid that provides proteins and benefits your metabolism. Lastly, Nuts are storehouses of protein. Sprinkle them over your breakfast cereal or add them to your evening snacks.