How much protein should we really eat? Five things to know

Potato chips. pastry Bottled water. If you’ve been to the grocery store lately, you’ve probably noticed that even the most unlikely produce now comes in protein-enhanced versions.

Protein mixing—the social media-fueled trend to maximize dietary protein at every opportunity—shows no sign of slowing down. That’s in part because the federal government has weighed in with nutritional guidelines that emphasize meat and dairy consumption and increase the Recommended Dietary Allowance of protein by 50% to 100% over the previous RDA.

Do we really need all that protein? Should we skip dinner for a T-bone steak?

“Protein has gotten the same treatment that the low-fat diet-snack fad in the ’90s. We’ve all given protein a health boost.” Marilee Opizzo, Ph.D., a dietitian and professor of medicine at the Stanford Prevention Research Center, said. “Protein intake is important. Not just magic-fixer-fontaine-of-fixer-fontaine-of-interest as Instagram will tell you.”

We asked Oppezzo and other Stanford medicine experts to help us break down protein fact and myth—and get to the science behind conflicting diet recommendations. Here are five key tips.

1. Protein consumption fuels the body’s creation of important proteins.

While conflicting dietary advice may muddy the waters, it’s clear that we need protein in our diets. Broadly speaking, all food can be divided into three major nutrients: carbohydrates, fats and proteins. And of course, most foods contain all three. But if you are consuming calories, it must come from one of these three sources.

Protein is necessary for many things in our body. At its molecular root, dietary protein provides many of the building blocks we need to build our body’s proteins, which in turn are used to build and perform every physical function imaginable.

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

Our body’s proteins—like 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 cannot make it from other parts.

When you eat dietary proteins, your body breaks down the long chains of amino acids into their components, which it then uses to make new proteins that your body needs. Imagine pulling all the beads out of a carpet and then using those beads to make a new type of jewelry.

2. For some people, protein intake is important for maintaining muscle mass.

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 about 55 grams of protein a day, or the equivalent of an 8-ounce steak. The new revised dietary guidelines instead recommend 1.2 to 1.6 grams per kilogram, which raises the recommendation for a 150-pound man to 80 to 110 grams per day.

That’s quite a leap – so what really changed with science? None, said Christopher Gardner, PhD, director of nutrition studies at the Stanford Prevention Research Center.

“Were we really out of it? Is there any new evidence to show we’re out of it? There really isn’t any,” Gardner said. “Protein is one of the most heavily marketed products I’ve ever seen. Everything is marketed with protein in it.”

Oppezzo’s opinion is somewhat more important. He is concerned about the protein intake of adults over 40 and the growing segment of the population who are taking medications to lose weight. For these two groups, there is evidence that eating more than 0.8 grams of dietary protein per kilogram can prevent the loss of muscle mass that usually accompanies aging and weight loss.

For those with a body mass index greater than 30, the calculation is a bit more complicated. Instead of using their actual body weight, they should use an “adjusted body weight,” Opizzo said, because losing weight requires energy to build and maintain. For her clients who are actively losing weight, such as those taking weight loss medications, she recommends 1.6 grams of protein per kilogram of adjusted body weight. This is because people who eat a low-calorie diet are at risk of losing muscle mass.

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

“The biggest thing that prevents muscle loss is strength training,” Opizzo said. “What adds to the high protein is the very small potatoes.”

3. Protein intake may not be a problem in the beginning.

Distinguishing between the old and new dietary guidelines may be impossible, because Americans already eat too much protein. According to the National Health and Nutrition Examination Survey, adult men in the United States eat 90 to 100 grams of protein per day, and women get 65 to 75 grams. It is already compatible with new offers.

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

The results of these studies are known as the estimated average need for protein, and it is only 0.66 grams per kilogram. To ensure they meet the needs of the entire US population, they set the RDA 20% higher. That 0.8 grams per kilogram is designed to meet the needs of 98% of American adults, Gardner said, so it shouldn’t be viewed as a minimum “hit.”

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

While consuming too much protein isn’t likely to be harmful in itself, 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, people may 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 in primarily plant-based foods. National surveys show that unlike protein, only 5% of Americans meet the RDA for fiber, which is important for gut health and reduces the risk of heart disease and other chronic diseases.

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

Gardner said there are many foods that contain both fiber and protein, such as beans and other legumes and whole grains. Unfortunately, these are not foods that Americans typically think of when it comes to protein.

“Americans hardly eat any nuts,” he said. The average American eats less than 10 grams of nuts 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 is no such thing as incomplete protein.

If there’s one protein myth that Gardner wants to die early, it’s the incomplete protein myth. For years, general nutritional advice has maintained that plant proteins are called incomplete proteins, while animal proteins are complete. If you get most of your protein from beans and legumes, it is advised, you need to include some grains in the same meal to make a difference.

It’s the bapkiss, says Gardner. Plant proteins do not lack any of the 20 amino acids, although they contain slightly fewer of those 20 than animal proteins. If a person eats only grains and does not have additional protein, low intake of a single amino acid may be a problem. But this is not the reality of the American diet.

“If you need 50 grams of protein a day and you’re only getting 50, you 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 this point the distribution should not be complete, because you have a lot of excess.”

Gardner and his colleagues published a paper in 2019 that debunked the protein deficiency myth: They compared the amino acid distributions in several different animal and plant foods and found that they were almost identical. A recent study even found that a vegan diet works just as well for building muscle as an omnivorous diet.

Oppezzo mentions a few other protein myths, such as that you can’t absorb more than a certain amount of protein at one time, so it should be spread evenly throughout your daily meals. While you may be eating 25 grams of protein at one time versus 75 grams in three meals, studies have shown that there is no difference in how your body metabolizes protein. However, for older adults, splitting the protein between multiple meals can ensure they are getting enough protein because as we get older, we may need more protein in a given meal to build muscle protein synthesis.

It’s also not the case that you should adjust protein immediately after strength training, she said. It is true that after exercise there is a so-called anabolic window, a period when your muscles repair themselves and can easily incorporate protein from your diet. But that window is about 24 hours, so just eat your normal meals for the rest of the day and don’t worry about downing a post-workout protein shake at the gym.

And finally, eating more than the RDA can have its drawbacks—even if it’s not 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?”