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- Protein is made up of amino acids and is one of three types of essential macronutrients.
- Protein is important because it builds muscle, digests food, and keeps skin firm and healthy.
- You need to eat at least 0.36 grams of protein per pound of body weight daily.
- Visit Insider's Health Reference library for more advice.
The human body consists of tens of thousands of proteins, which are found in every cell of your body, making them an essential part of anyone's diet. Protein also provides a number of other health benefits. Here is how much you need and the best protein food sources you can buy.
What is protein?
Protein is one of three types of essential macronutrients, the other two being carbohydrates and fats. They are made up of amino acids, organic compounds, and they help grow and maintain the body's tissues – including muscles, tendons, blood vessels, and skin.
Therefore, eating protein every day is essential to maintain key bodily functions like building tissues and digesting foods.
Why is protein important?
Unlike carbohydrates or fats, your body doesn't store protein, meaning you need to eat it every day. Protein is also the only macronutrient that contains nitrogen, a structural component of amino acids that humans can only acquire through food.
Protein's health benefits include:
- Builds lean muscle mass when combined with resistance exercise. Proteins also maintain current muscle mass.
- Boosts the immune system by stimulating white blood cells to help your body fight off infection.
- Assists in weight loss by keeping you fuller for longer. It also takes more calories to digest compared to fat or carbs.
- Keeps skin firm and healthy thanks to its role in building and maintaining body tissue.
- Supports proper growth and development, especially in childhood, adolescence, and pregnancy.
- Helps digest food as proteins create the enzymes necessary for breaking food down into energy.
- Regulates hormones, particularly during puberty.
How much do you need every day?
The US Food and Nutrition Board of the Institute of Medicine recommends a daily protein intake of at least 0.36 grams of protein per pound of body weight, or 0.8 grams per kilogram.
Therefore, an adult who weighs 150 pounds should eat at least 54 grams of protein a day. Calorie-wise, protein should take up about 10% to 35% of your daily intake.
However, some people may need more protein, like:
- Athletes need protein to maintain and repair muscle tissue, which intense physical exercise can break down. For example, marathon runners may require 1.4 to 2.0 grams of protein per kilogram of body weight a day.
- Older adults typically need 1.0 to 1.2 grams per kilogram of body weight. As we age, our bodies do not process amino acids as efficiently. We also lose muscle mass, which decreases overall strength and mobility.
- Pregnant or nursing women need at least 71 grams of protein per day to help build the baby's muscles, bones, and tissues.
- People recovering from surgery need more protein to help repair skin and tissues.
Most American adults get enough protein, though some 46% of adults over 70 don't have adequate intake. Not consuming enough protein results in a protein deficiency, which can reduce your muscle mass, impair your immune response, and reduce bone density, leading to osteoporosis.
"Certain fad diets set us up to have a health halo over all types of protein, thinking more is better. But as in any macronutrient, if you have an overabundance of protein, it will equate to extra calories and be stored as fat or adipose tissue," says Christine Patorniti, a registered dietician and certified diabetes educator in Centennial, Colorado.
Types of protein
Both animal and plant foods have protein. However, animal products are complete proteins, containing all of the nine essential amino acids your body needs to function. Meanwhile, plant-based sources of protein are more likely to be incomplete, lacking a sufficient quantity of one more of the essential amino acids.
Therefore, vegetarians and vegans will need to eat a variety of plant proteins to take all in the amino acids plus other nutrients their bodies need, says Patorniti.
However, compared to animal protein sources, plant proteins may promote lower blood sugar and cholesterol levels. In fact, a large 2020 review found people who ate diets high in plant-based protein had an 8% lower risk of death from any cause over 32 years.
High protein foods
| Food | Serving Size | Protein grams (g) | % Daily Value (DV) |
| Beef, cooked | 3 ounces (oz) | 23.4 | 46.8% |
| Chicken breast, boneless, skinless | 3 oz | 25.9 | 51.8% |
| Tuna fish | 3 oz | 24.8 | 49.6% |
| Tofu, raw | 1/2 cup | 10 | 20% |
| Large egg | 1/2 cup | 6.25 | 12.5% |
| Black beans | 1 cup | 15.2 | 30.4% |
| Cheddar Cheese | 1 slice | 6.78 | 13.56% |
| Peanuts, dry roasted | 1 oz | 7 | 14% |
A powder or drink supplement can help you meet your daily protein requirement, but can also be high in sugar, salt, and preservatives, which could negatively impact your health, says Kelsey Mangano, PhD, an assistant professor and Nutrition Program Director at the University of Massachusetts Lowell. Meanwhile, protein from whole foods contains other important nutrients like vitamins, fiber, and iron.
Insider's takeaway
Protein is a macronutrient composed of amino acids that your body relies on for many critical functions like building muscle and fighting infection. You should aim to eat at least 0.36 grams of protein per pound of body weight
a day, but this varies depending on weight, age, activity level, and goals High protein foods come from both animal and plant sources. Whichever type you choose, make sure to include a variety of sources throughout the day.