“We tend to consume more than enough protein already,” says Roger A. Fielding, senior scientist at the Jean Mayer USDA Human Nutrition Research Center on Aging (HNRCA) and professor at the Friedman School of Nutrition Science and Policy. 

According to a national survey, 85% of Americans meet or exceed the recommended amount of protein. 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), or 0.36 grams per pound. One study found the majority of U.S. adults eat somewhere around 1.0 to 1.5 g/kg/d, well above the recommended 0.8 g/kg/d.

There are some circumstances where this extra protein may be warranted:

Building Muscle 

While simply increasing protein intake has not been shown to build muscle, it may help increase muscle strength when combined with a program of regular muscle-building exercise. 

“During aerobic or strength training activities, protein turnover increases,” Fielding explains. “In other words, your body may break down more protein than it is making. An abundance of evidence suggests people who are physically active probably require more dietary protein per day—up to 1.1 g/kg—to make up the difference. But keep in mind, most people in the U.S. already consume at least this much protein.”

Aging

Some studies suggest older adults could benefit from getting a bit more than the RDA for protein, but the jury is still out. “As we age, we lose muscle mass,” says Fielding. “If an older adult is eating a low protein diet or not consuming protein throughout the day, muscle loss may be accelerated.” 

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In a number of studies, high-protein interventions did not help maintain muscle mass in adults aged 65 or older who already consumed adequate amounts of protein at baseline. However, other studies, including a long-term study led by Tufts researchers, found higher protein intake across adulthood was associated with significantly lower risk of losing physical function with age, particularly in women.

While the U.S. RDA for protein is 0.8 g/kg/d (0.36 g/lb) for adults of all ages, some international expert groups recommend a protein intake of 1.0 to 1.2 g/kg/d for adults over 65 years old. The participants in the Tufts’ study were averaging protein intake of 1.0 g/kg/d, indicating most older adults in the U.S. don’t necessarily need to change their eating habits to meet this higher intake goal.

Weight Management

If you are cutting calories to lose weight, be careful to keep your intake of protein foods at the recommended level. 

“When people cut calories across the board, they generally cut protein intake along with carbohydrates and fats,” says Fielding. “If the body is not getting enough dietary amino acids to build all the proteins it needs, it will break down muscle tissue to get to the amino acids stored there. These dieters will lose body fat, but also lean mass (muscle).” 

Making sure a higher percentage of calories on a low-calorie diet comes from protein can help.

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