Around 60% of adults in the U.S. report they are trying to eat more protein. But do they really need to?

By the Numbers

The actual amount of dietary protein you need depends on a number of factors, including your size, age, sex, activity level, and health status. The Recommended Dietary Allowance (RDA) for protein in the U.S. is 0.8 grams per kilogram of body weight per day (g/kg/d) (0.36 grams per pound). Some research suggests adults who are physically active may benefit from more—up to 1.1 g/kg/d. 

It may surprise you to learn that most Americans already meet or exceed the recommended protein intake. It is estimated the vast majority of U.S. adults eat somewhere around 1.0 to 1.5 g/kg/d.

Protein Benefits

Proteins are built from a mixture of 20 amino acids, some of which are essential, meaning our bodies can’t make them so we need to get from food. Protein plays many important roles in the body, but it may be best known as the building block of muscle. 

“Just increasing protein intake does not build muscle, but protein may help increase muscle strength when combined with a program of regular muscle-building activity,” says Roger A. Fielding, Ph.D., who studies age-related muscle loss at the Jean Mayer USDA Human Nutrition Research Center on Aging (HNRCA). “Additionally, if an older adult is not getting enough protein, the natural muscle loss that comes with aging may be accelerated.” Fielding also recommends people on a low-calorie diet make sure they are getting enough protein to avoid losing muscle along with fat.

More is Not Always Better

There are some health concerns associated with very high protein intake.

Kidney function: Protein influences how hard the kidneys work. While current data seem  to indicate healthy kidneys can handle protein intake above the required amount, people with reduced kidney function should stick to the recommended 0.8 g/kg/d to minimize any excess burden on the kidneys.

Bone Health: “High intake of protein combined with low intake of fruits and vegetables may cause a problem for our bones,” says Bess Dawson- Hughes, who studies bone health at the HNRCA and is also a professor of medicine at Tufts University School of Medicine. “The digestion and absorption of protein (and grains) increases the level of acid in the blood. This excess acid is neutralized with alkaline compounds obtained by the breakdown of bone—so too much protein could actually end up weakening bones. Vegetables and fruits, on the other hand, add acid-neutralizing compounds to the body when they are broken down (even acidic fruits like citrus).” 

Most Americans need more fruits and vegetables, less grains (especially refined grains), and protein in line with recommendations.

Unbalanced Nutrition: High-protein diets are often low in plant foods and rely heavily on animal products. Such a dietary pattern can be high in sodium and saturated fats, and low in healthy foods like fruits, vegetables, whole grains, legumes and healthy plant oils, as well as fiber. 

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Added vs. Natural

Protein is found naturally in animal sources (meat, poultry, seafood, dairy, and eggs) and plant sources (tofu and other soy foods, beans, lentils, and nuts and seeds). Food manufacturers extract protein from natural sources like milk (whey protein), soybeans (soy protein), and legumes (like pea protein), process it, and add it to all kinds of foods.

As we’ve established, most Americans already meet or exceed the recommended protein intake and don’t need these added proteins. Importantly, added proteins are often found in ultraprocessed foods high in sodium and/or added sugars and other refined carbohydrates. A mix of natural plant and animal (or only plant) sources is the best choice for health.

Aim to get most of your protein from natural sources. The “Protein Needs and Sources” table below can help you get an idea of what that might look like.

Protein Needs and Sources

1. Calculate your protein needs. Multiply your weight in pounds by 0.36. This is your Recommended Daily Allowance for protein (equivalent to .8 g/kg/day). Note: People who regularly engage in muscle-building exercises may benefit from protein in take at or around 0.45 grams per pound (1.0 g/kg/day).

2. Use the chart below to get an idea of what combinations of foods you can use to meet your protein needs. Remember to choose fish, legumes, nuts/seeds, or other plant sources more often in place of red and processed meats and added proteins in ultraprocessed foods.

*For reference, a three-ounce serving of cooked beef, lamb, pork, or poultry is about the size of a deck of cards. 

**For reference, a three-ounce serving of thicker fish (like salmon steak) is about the size of a deck of cards. For thin fish fillets like flounder or tilapia, three ounces is roughly the size of a checkbook or a bit longer than a standard cellphone. 

+An ounce of cheese is about the size of four dice.

This article originally appeared in the Tufts Health & Nutrition Letter, published each month by the Friedman School of Nutrition Science and Policy.