How Much Protein Do You Need? Experts Explain

Snack bars, yogurt, ice cream and even bottled water: It seems food manufacturers have found ways to incorporate extra protein into almost everything as they seek to capitalize on a growing consumer trend.

Today, protein-fortified foods and protein supplements form a market worth tens of billions of US dollars, with fitness influencers, as well as some researchers and doctors, promoting high-protein diets as the secret to strength and longevity. Protein is undeniably essential, but how much people actually need remains a matter of debate.

On the one hand, most official guidelines recommend a minimum of nearly one gram of protein per kilogram of body weight per day, or the equivalent of about 250 grams of cooked chicken (which contains about 68 g of protein) for an adult weighing 70 kilograms. On the other hand, a growing narrative in wellness circles encourages people to eat more than double that amount. Many scientists fall somewhere in between and take issue with some of the advice circulating online.

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“It’s really frustrating because there’s no evidence to support their claims,” says Katherine Black, an exercise nutritionist at the University of Otago in Dunedin, New Zealand, referring to the high-protein recommendations often shared on social media. What research shows is that protein needs can vary from person to person and can change throughout life. And people should think carefully about what they eat to meet these needs. “On social media, it’s like everyone is worried about protein and putting protein powder in everything,” she says.

Health authorities can help guide citizens’ food choices based on the latest research. The upcoming Dietary Guidelines for Americans, a document that provides advice on what to eat to maintain a healthy lifestyle, is expected to be released by the end of this year. But its recommendations, which tend to have great influence, could change.

Calculate protein requirements

Researchers have been trying to estimate how much protein people need for more than a century. In 1840, chemist Justus von Liebig estimated that the average adult needed 120 grams of protein per day, based on the diet of a group of German workers. Later, scientists began using nitrogen to calculate protein requirements. Protein is the only major dietary component containing nitrogen. So by measuring how much people consume and how much they excrete, researchers could estimate how much the body uses.

Since the 1940s, this method of nitrogen balance has been used to determine Recommended Dietary Allowances (RDA), a set of nutritional recommendations developed by the United States National Academies of Sciences, Engineering, and Medicine.

The last such recommendation for protein, from 2005, sets the recommended daily allowance for men and women at 0.8 grams per kilogram of body weight per day, which it says should be enough to meet the needs of 97 to 98 percent of healthy people. European and global health authorities recommend similar or slightly higher levels.

Although scientists agree that RDAs are a useful benchmark, many argue that people could benefit from a higher amount. “The RDA is not a target; it’s simply the minimum that seems to prevent any detectable deficiency,” says Donald Layman, a researcher specializing in protein requirements at the University of Illinois at Urbana-Champaign. Data suggests the optimal range is between 1.2 and 1.6 grams of protein per kilogram of body weight per day, he says.

This is especially true for older adults, who often experience muscle loss as they age, as well as some athletes and people trying to gain muscle.

For example, in an observational study of 2,066 adults aged 70 to 79, those who reported eating the most protein – about 1.1 grams per kilogram of body weight – lost 40% less lean mass over the three years of follow-up than those who ate the least – about 0.7 grams per kilogram.

“For older people, 1.2 grams per kilogram only gives them a little extra protection,” says Nicholas Burd, a nutrition and exercise researcher also at the University of Illinois at Urbana-Champaign. Additionally, older adults may experience a decreased appetite, making it especially important that they pay attention to their protein intake. That doesn’t mean they have to take protein supplements, he says. “That’s all we can do with just the normal incorporation of protein-rich foods into our lives.”

For healthy adults, increasing protein may enhance the effects of resistance exercises, such as weightlifting. A 2017 systematic review found that, among people engaged in this type of training, taking protein supplements improved muscle gain and strength. But increasing protein beyond 1.6 grams per kilogram per day provides no additional benefit.

Meanwhile, some fitness influencers swear by consuming 2.2 grams per kilogram of body weight. For most people, that’s just overkill, Burd says. There’s little danger except for people with kidney disease, but Burd adds: “You’re just creating an inefficient system where your body becomes very efficient at wasting food protein.” »

Some practitioners might recommend higher protein targets to ensure people are getting enough, Burd says. But the protein craze is mainly due to aggressive marketing of protein-rich foods and supplements, he says.

“The myth of increased protein needs has infiltrated the popular imagination, including among health professionals, and has been reinforced by the food industry,” says Fernanda Marrocos, a researcher specializing in nutrition and food policy at the University of São Paulo in Brazil.

Amino acid goals

Not all proteins are the same, and some researchers are arguing for a more nuanced recommendation that takes into account the amino acids — the building blocks of proteins — that foods contain. The human body requires 20 amino acids to function properly, 9 of which are considered “essential” because they can only be obtained through diet.

The rest of these nine foods in animal foods are exactly what other animals need, says Layman. “In plants, the essential amino acids are generally there, but they are proportioned to the plants.” This means that some plants may be rich in certain amino acids but not others. Therefore, meeting amino acid requirements with plant-based products may require a wider variety of foods.

He criticizes the way official dietary guidelines calculate protein recommendations from different sources. For example, according to the U.S. Department of Agriculture, 14 grams of almonds can replace 28 grams of chicken breast. Research by Layman and colleagues, which examines amino acid balance, suggests that it would actually take more than 115 grams of almonds to replace 28 grams of chicken.

Robert Wolfe, a researcher specializing in muscle metabolism at the University of Arkansas for Medical Sciences in Little Rock, says dietary guidelines should incorporate analysis of protein quality, including the balance of amino acids and how well the human body can digest them.

According to Wolfe, one area for future research is to understand exactly how food processing affects protein content. Factors such as cooking temperature, for example, can influence how the body digests protein. This may have implications for certain protein supplements and high-protein bars, which are typically highly processed.

Obtaining this information requires going beyond nitrogen balance studies. Wolfe’s team used isotope tracers to determine the rate at which dietary proteins are incorporated into new proteins in the body. A study of 56 young adults, for example, concluded that consuming animal-based protein led to a greater gain in body protein than consuming an equivalent amount of plant-based protein. But studies in this area are still limited and should not be interpreted to mean that people should get all their protein from animal sources.

The American Heart Association recommends prioritizing plant-based proteins, since saturated fats found in red meats may increase the risk of cardiovascular disease. Meat production, which is a major source of greenhouse gas emissions, also has a high environmental cost.

Burd says that if a diet includes at least some animal-based protein, it will likely provide all of the essential amino acids for maintaining good health. And it’s possible to get the same benefits with plant-based proteins alone. “This is where supplements could be beneficial, because it’s more difficult to achieve this balance from plants alone,” says Burd.

Experts who advised the formulation of the next Dietary Guidelines for Americans say most Americans already consume more than enough protein. They suggest reducing protein intake from red meat, chicken and eggs and increasing intake of certain vegetables. But it is not clear what these guidelines will contain: US Secretary of Health Robert F. Kennedy Jr. has said in recent months that he will emphasize the need to consume saturated fats especially from meat and dairy products, which goes against the recommendations of many medical associations.

Protein consumption is adequate in most parts of the world, says Marrocos. A study his team conducted in Brazil found that in general, people consume far more than the World Health Organization’s recommendations for protein, even those with the lowest incomes. So there’s no need to obsess about getting an exact protein count.

“For most people, as long as they eat enough calories and eat a reasonably varied diet, they will get all the protein they need,” says Marrocos.

This article is reproduced with permission and has been published for the first time on November 12, 2025.