Complete proteins are foods that contain all nine essential amino acids in adequate amounts. Meat, poultry, fish, eggs, dairy and whole soy foods such as tofu, edamame and tempeh are complete. Most beans, grains, nuts and seeds are incomplete, but eating a variety of them over the day can cover your needs.
Protein is built from smaller units called amino acids. MedlinePlus, from the U.S. National Library of Medicine, sorts them into three groups:
Essential amino acids can't be made by your body, so they must come from food. There are nine: histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine.
Nonessential amino acids are ones your body can make, even if you don't eat them.
Conditionally essential amino acids are usually not essential, except in times of illness and stress.
Cleveland Clinic explains that a food is considered a complete protein when it contains adequate amounts of all nine essential amino acids. An incomplete protein may still contain all nine, but some in lower amounts. "Incomplete" doesn't mean bad. As Cleveland Clinic puts it, each of these foods brings something to the table, and a healthy combination of them can give you everything you need.
Grams are approximate, from USDA FoodData Central (SR Legacy data), and rounded. Meat and fish are cooked weights.
Animal foods. Cleveland Clinic lists fish, poultry, eggs, beef, pork and dairy as complete:
Chicken breast, roasted, 3 ounces: about 26 grams of protein
Lean top sirloin steak, 3 ounces: about 26 grams
Salmon, cooked, 3 ounces: about 19 grams
Plain nonfat Greek yogurt, 6-ounce container: about 17 grams
Low-fat (1%) cottage cheese, 1/2 cup: about 14 grams
Milk (2%), 1 cup: about 8 grams
Egg, 1 large: about 6 grams
Whole soy foods. Cleveland Clinic also counts whole sources of soy, like tofu, edamame, tempeh and miso:
Soybeans, cooked, 1 cup: about 31 grams
Edamame, 1 cup: about 18 grams
Tempeh, 3 ounces: about 17 grams
Firm tofu, a quarter block: about 7 to 14 grams, depending on the type (USDA lists both)
You will often read that quinoa is a complete protein. Harvard's Nutrition Source does call quinoa and chia seeds complete plant proteins. Cleveland Clinic's list of complete proteins sticks to animal foods and whole soy, and it puts whole grains, nuts and seeds with the incomplete proteins.
Either way, the amounts are modest. A cup of cooked quinoa has about 8 grams of protein and an ounce of chia seeds about 5. Enjoy them, but they work best next to beans, tofu, dairy or eggs rather than as your main protein.
Cleveland Clinic lists legumes (beans, peas and lentils), nuts, seeds, whole grains and vegetables as incomplete proteins. Many of them still carry a good amount:
Beans, lentils and peas: a cup of cooked lentils has about 18 grams, black beans about 15 and chickpeas about 14.5.
Nuts and seeds: 3 tablespoons of hulled hemp seeds have about 9.5 grams, 1 ounce of roasted pumpkin seeds about 8.5, 2 tablespoons of peanut butter about 7 and 1 ounce of almonds about 6.
Whole grains: a cup of cooked brown rice has about 5.5 grams, 1/2 cup of dry oats about 5 and a slice of whole-wheat bread about 4.
Vegetables: a cup of cooked spinach has about 5 grams.
Harvard's Nutrition Source adds a useful point: the whole "protein package" matters for health, meaning the fat, fiber and sodium that come along with the protein, not just the grams.
The traditional idea, sometimes called protein combining, is to pair a bean, lentil or soy food with a grain, nut or seed. Rice and beans is the classic example. These pairings are handy and tasty, but optional:
Rice and beans: 1 cup of brown rice with 1 cup of black beans. About 21 grams.
Lentil soup and bread: 1 cup of cooked lentils with 1 slice of whole-wheat bread. About 22 grams.
Oatmeal with soy milk and hemp seeds: 1/2 cup of dry oats cooked in 1 cup of unsweetened soy milk, topped with 3 tablespoons of hemp seeds. About 22 grams.
Tofu stir-fry with rice: a quarter block of firm tofu and vegetables over 1 cup of brown rice. About 13 to 20 grams, depending on the tofu.
Bean tacos: 1 cup of cooked pinto beans in 2 corn tortillas. About 18 grams.
Peanut butter toast: 2 tablespoons of peanut butter on 2 slices of whole-wheat bread. About 15 grams.
Hummus and pita: 1/4 cup of hummus with 1 large whole-wheat pita. About 11 grams.
Looking for more ideas? See our list of high protein vegetarian foods with grams for each.
No. It's a common worry, but the advice has moved on.
MedlinePlus says you don't need to eat essential amino acids at every meal, and that getting a balance of them over the whole day is what matters. It adds that experts no longer worry about pairing proteins, such as beans with rice, at a single meal.
Cleveland Clinic agrees: aim for a balance of essential amino acids over the course of the day, and eat a wide variety of legumes, lentils, nuts, seeds and whole grains daily if you eat little or no meat.
MedlinePlus also notes that a diet based on a single plant food won't be adequate. Variety is the key.
And you don't need animal products at all. MedlinePlus states that you do not need to eat animal products to get all the protein you need.
For the bigger picture of what protein actually does, read what protein does in the body.
A registered dietitian can help you plan if you are moving to a vegetarian or vegan diet, are pregnant or breastfeeding, have kidney disease, or have a food allergy to soy, milk, eggs, peanuts or tree nuts. Ask your doctor before making big changes if you have a health condition or take medicine that affects your appetite.
This is general information, not medical advice. Talk to your doctor or pharmacist about your own situation.
Yes. Eggs are on Cleveland Clinic's list of complete proteins. One large egg has about 6 grams of protein.
Cleveland Clinic groups nuts with the incomplete proteins. Peanut butter is still a useful source, with about 7 grams in 2 tablespoons, and it pairs well with whole-wheat bread.
Rice and beans is the classic plant pairing. You don't have to eat them at the same meal, though. MedlinePlus says the balance over your whole day is what counts.
Yes. Eggs, dairy and whole soy foods like tofu, tempeh and edamame are complete, and a varied plant-based diet can supply all nine essential amino acids over the day.
Sturdy: Strength on GLP-1 is an iPhone app for adults using GLP-1 or other prescribed weight-management medication. It lets you log protein by meal period with favorites, custom foods, saved meals and label-based entry, and any estimates are clearly labeled as estimates. It needs no account, has no ads, and is free with an optional Sturdy Pro subscription.
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Protein (The Nutrition Source, Harvard T.H. Chan School of Public Health)
FoodData Central, SR Legacy food data (USDA Agricultural Research Service)