Not all sources of protein are equal. Different products contain different combinations of amino acids. Including a good variety of protein-rich foods in your diet to ensure good protein intake. "High-quality" protein, such as meat, chicken and eggs, is especially important for muscle maintenance and growth.

Choose proteins low in saturated fat. Fish, for example, contains essential Omega-3 fatty acids, which are good for your heart, brain and eye health. Dairy products, such as milk and yogurt, are also great sources of protein. Those who are lactose intolerant will not be able to drink milk, however, yogurt is usually a good choice, since most of the lactose has been removed.

White-meat poultry, such as chicken and turkey with the skin removed, is a healthier option than red meat, as poultry is generally lower in saturated fat and contains high-quality protein. You may include lean beef and pork into your diet to enjoy every once in a while.

Protein can be found in other foods besides animal products. Quinoa, beans, peas, tofu and nuts are rich in vegetable protein and are great low-fat alternatives.