Protein is essential for growth, energy, and tissue repair. Athletic performance depends on muscle strength, and muscles are made of protein. Although athletes who are involved in strength and endurance training may need slightly more protein, it’s a mistake to think you can simply build up muscles by eating lots of protein. Exercise, not dietary protein, increases muscle mass.
The amount of protein adolescents need varies at different stages of development. As a rule, boys and girls between ages 11 and 14 need half a gram per pound of body weight daily. Thus, a young teenager weighing 110 pounds needs about 50 g of protein a day. Between ages 15 and 18, the RDA drops slightly. As with all essential nutrients, common sense is the rule—you don’t have to weigh every gram on a scale. Each gram of protein provides 4 calories—the same as carbohydrates—and protein should make up about 10% to 12% of each day’s calories. As a general rule, there are approximately 22 g of protein in 3 oz of meat, fish, or poultry. An 8-oz glass of milk contains about 8 g of protein. Therefore, an average teenager who is drinking 3 glasses of milk a day does not need enormous amounts of meat to meet his daily protein requirement.
The protein in foods of animal origin is termed complete or high-quality protein because it contains all the essential amino acids in about the proportions humans need. Vegetable proteins are called incomplete because, except for soybeans, they have low levels of one or more essential amino acids. You don’t have to eat animal products to obtain high-quality protein, however.
People on vegetarian diets take care of their protein needs by pairing plant foods that balance each other’s shortfalls. Pairing foods in this way is called protein complementation. Eating a grain and a legume does the trick; beans and tortillas, a peanut butter sandwich on wheat bread, and black-eyed peas and rice are good examples of protein complementation. You can also compensate for any lack in a plant-based food by adding a small amount of animal-derived protein, such as in pasta with cheese or cereal with milk.
Protein and Calorie Content of Foods Most Teenagers Like to Eat
| Bagel (1 medium)
| Bread, whole wheat, 1 slice
| Cheese, processed, American (1 oz)
| Cheeseburger (4-oz meat patty)
| Lean meat, fish, or poultry
| Milk, reduced-fat (2%). low-fat (1%), or nonfat (skim) milk
| Peanut butter (1 tablespoon)
| Pizza, cheese (1 slice)
| Yogurt, low-fat, coffee or vanilla (8 oz)