5 Things Experts Say You’re Getting Wrong About Protein

Seems like it always comes down to balance

By Rachel Tompa, Stanford University

Walk through a grocery store today, and you will likely see protein added to everything from potato chips and pastries to bottled water. Products that once had little connection to nutrition trends are now marketed as protein-rich options.

This surge reflects the rise of “protein-maxxing,” a social media-driven push to increase protein intake at every opportunity. The trend has gained further traction as federal dietary guidelines now highlight meat and dairy consumption and recommend increasing protein intake by 50% to 100% compared to earlier guidelines.

But is all this extra protein necessary? Should carbohydrates be replaced with steak?

“Protein has gotten the kind of treatment that low-fat food did in the ’90s—the SnackWell’s phenomenon. We all have given protein a health halo,” said Marily Oppezzo, PhD, a dietician and instructor of medicine at the Stanford Prevention Research Center. “Protein intake is important. Just not as magical-fixer-fountain-of-instant-awesome as Instagram would tell you.”

To separate fact from hype, Stanford Medicine experts reviewed the science behind protein and current dietary advice.

1. Protein intake fuels the creation of important bodily proteins.

Despite conflicting messages, one point is clear: protein is essential. Along with carbohydrates and fat, it is one of the three macronutrients that supply calories. Every calorie you consume comes from one of these three sources.

Protein plays a critical role throughout the body. At a basic level, it provides the raw materials needed to build the body’s own proteins, which support nearly every biological process.

“Protein can take the form of your muscles, your hair, your skin—everything has protein in it,” said Jonathan Long, PhD, an associate professor of pathology. “And you can’t get those constituents from fat or carbohydrates alone.”

Our bodies’ proteins — just the same as dietary proteins — are made up of strings of molecules called amino acids. There are 20 different amino acids, some of which we can synthesize from other compounds. But we must get nine of these, also called essential amino acids, from our diet. We simply can’t build them out of other components.

When you eat dietary proteins, your body breaks down those long strings of amino acids into their component parts, which it then uses to build new proteins your body needs. Imagine pulling all the beads off of a necklace and then using those beads to make new kinds of jewelry.

2. For some people, protein amounts are important for muscle retention.

Until just a few months ago, the federal RDA of dietary protein for adults was 0.8 grams per kilogram of body weight. For a 150-pound adult, that’s around 55 grams of protein a day, or the equivalent of an 8-ounce steak. The newly revised dietary guidelines instead recommend 1.2 to 1.6 grams per kilogram, raising that 150-pound person’s recommendation to 80 to 110 grams a day.

That’s quite a jump — so what actually changed with the science? Nothing, said Christopher Gardner, PhD, the director of nutrition studies at the Stanford Prevention Research Center.

“Were we really off by that much? What new evidence became available to show that we were off by that much? There really isn’t any,” Gardner said. “Protein has become one of the single most heavily marketed products I’ve ever seen. Everything is marketed with protein in it.”

Oppezzo’s view is slightly more nuanced. She’s concerned about the protein intake of adults over 40 and the growing segment of the population taking medications to lose weight. For these two groups, there is evidence that eating more dietary protein than 0.8 grams per kilogram can help stave off some of the muscle loss that commonly accompanies aging and weight loss.

For individuals with a body mass index above 30, protein needs are calculated differently. Instead of using total body weight, an “adjusted body weight” is used because lean tissue requires energy to maintain. For those actively losing weight, Oppezzo recommends about 1.6 grams per kilogram of adjusted body weight to help preserve muscle.

However, Oppezzo points out that resistance training is far more important than what you eat to maintain your muscles. One of her mentors, McMaster University nutrition researcher Stuart Phillips, PhD, likes to say that protein isn’t the cake, exercise is — protein is only a thin layer of frosting on the cake of resistance training.

“The biggest thing that stops muscle loss is strength training,” Oppezzo said. “What higher protein adds to that is pretty small potatoes.”

3. Maybe there wasn’t a protein intake problem to begin with.

The difference between the old and new dietary guidelines could be moot, because Americans are eating plenty of protein already. According to the National Health and Nutrition Examination Survey, adult men in the U.S. are eating around 90 to 100 grams of protein a day, and women are getting 65 to 75 grams. That’s already in line with the new recommendations.

Some people think that the old RDA was a suggested minimum and that more protein is always better. But that’s a misconception, Gardner said. In the 1980s, scientists calculated adults’ protein needs through controlled diet studies in which they measured everything that went in and everything that came out.

The outcome of those studies is known as the estimated average requirement for protein, and it’s only 0.66 grams per kilogram. To make sure they were meeting the needs of the entire U.S. population, they set the RDA 20% higher. That 0.8 grams per kilogram was designed to meet the needs of 98% of American adults, Gardner said, so it shouldn’t be viewed as a minimum to “beat.”

4. With all the protein talk, we might be neglecting fiber.

While overconsuming protein likely isn’t harmful on its own, it’s important to look at where that extra protein is coming from, Gardner said. If it’s from red meat, as the new dietary guidelines emphasize, folks might be consuming unhealthy levels of saturated fat.

And if we fill up on steaks and protein shakes, we’re not eating enough fiber and other nutrients found primarily in plant-based foods. National surveys show that, unlike for protein, only 5% of Americans are meeting the RDA for fiber, which is critical for gut health and reducing the risk of cardiovascular and other chronic diseases.

“There are all kinds of antioxidants that can lower inflammation and prevent cancer, and those don’t come in meat and cheese and protein bars,” Gardner said.

Foods like beans, legumes, and whole grains provide both protein and fiber, yet they are often overlooked when people try to increase protein intake.

“Americans hardly eat any legumes,” he said. The average American eats less than 10 grams of legumes per day. “There’s plenty of room to increase that and get your fiber, your antioxidants and your plant protein, and have enough.”

5. There’s no such thing as incomplete protein.

If there’s one protein myth that Gardner wishes would die already, it’s the fable of the incomplete protein. For years, common nutrition advice has posited that plants contain so-called incomplete proteins, while animal proteins are complete. If you’re getting most of your protein from beans and legumes, the advice goes, you need to pair them with certain grains at the same meal to make up the difference.

That’s bupkis, Gardner says. Plant proteins are not missing any of the 20 amino acids, although legumes have slightly less of one of those 20 than do animal proteins. If a person was eating only legumes and no excess protein, that lower amount of the single amino acid might be a problem. But that’s not the reality of the American diet.

“If you need 50 grams of protein a day and you got only 50, then you’d have to be careful that it’s the right kind. But most Americans eat 80, 90, 100 grams of protein a day,” Gardner said. “At that point the distribution doesn’t have to be perfect, because you have so much extra.”

Gardner and his colleagues published a paper in 2019 debunking the incomplete protein myth: They compared amino acid distributions in several different animal and plant foods and found that they’re nearly identical. A recent study even found that a vegan diet works just as well for muscle building as does an omnivore diet.

Oppezzo notes a few other protein myths, namely that you can’t absorb more than a certain amount of protein at once, so it needs to be evenly distributed throughout your daily meals. While you might find it easier to eat 25 grams of protein in three meals than 75 grams all at once, studies have shown that there’s no real difference in how your body metabolizes protein by doing so. For older adults, however, splitting the protein among multiple meals can help ensure they get enough protein because, as we get older, we may need more protein within a given meal to trigger muscle protein synthesis.

It is also not necessary to consume protein immediately after a workout. While there is an “anabolic window” when muscles repair and use nutrients more efficiently, it lasts about 24 hours. Eating regular meals throughout the day is sufficient.

And finally, eating more than the RDA can have its drawbacks — even if it’s not coming from protein-packed potato chips or pastries.

“I don’t think a high-protein diet is necessarily bad, but what are you not eating?” Oppezzo said. “Are you missing out on the fiber, vitamins, phytochemicals and antioxidants that vegetables, fruits, whole grains, and nuts provide?”