Of the three macronutrients that make up our diet (carbs, protein, and fats), protein often gets all the glory.
And, yeah, it’s pretty magical. Protein is a part of all cell structures (like our organs and muscles), and it helps us build enzymes and hormones, support our immune system, and feel full, says Lauren Harris-Pincus, M.S., R.D.N., author of The Protein-Packed Breakfast Club. All important things—especially if you’re physically active!
But that doesn’t mean you need to eat chicken breast for every meal of the day. Get your head straight about these protein myths to make sure you’re getting the most benefit out of this muscle-building macro.
Myth #1: More protein is always better.
Exactly how much protein you need per day depends on a few things, like your size, sex, and activity level. But generally, the most you really need is about a gram per pound of lean body mass per day (if you’re working out really hard), says Albert Matheny, M.S., R.D., C.S.C.S., co-founder of SoHo Strength Lab. The key here is lean body mass. So if you weigh 200 pounds and 175 of that is lean mass, you’d need 175 grams of protein per day. (Most gyms or trainers can help you estimate your lean body mass.)
When you eat protein, your body breaks it down into molecules called amino acids, which are then sent to your muscles and tissues where needed. “The body can use about 25 to 30 grams of protein at a time for things like muscle growth and repair,” says Harris-Pincus. For example, a smaller woman who trains a few times can probably utilize about 20 grams at a time, while a larger, active guy may tap out around 35 grams per sitting, says Matheny. Once you’ve fulfilled your body’s needs, any protein you consume is just extra calories.
“Too much of anything can be a problem,” says Matheny. So eating tons of processed foods like bacon just because they contain protein isn’t a great idea. Look at the food as a whole, not just its protein content. “Get your protein from whole foods instead of processed stuff that comes along with additional calories but few nutrients,” says Harris-Pincus.
Myth #2: Protein automatically goes to your muscles.
So now you know that your body can only use about 25 to 30 grams of protein for your muscles and tissues at a time. Anything beyond that is a different story…
Protein is great and all, but it does still have calories—four calories per gram, to be exact. The protein your body can’t use for its primary purpose basically gets broken down like a carb, says Matheny. That means it’s either used for energy or stored as fat. So, hate to burst your bubble, but more protein doesn’t automatically equal more muscle.
It’s all about balance: Too much protein (and calories) and you can still gain weight, says Harris-Pincus. Meanwhile, too few calories (even if they’re all protein) and you won’t build an ounce of muscle, says Matheny. “If you’re not meeting your calorie needs, your body focuses on maintaining the muscle it already has, not building more,” he says.
Myth #3: Plant proteins aren’t as good as animal proteins.
No two proteins are created equal—but that doesn’t mean they don’t all deserve a spot in your diet. Different protein sources contain different types and amounts of amino acids, and there are nine ‘essential’ amino acids we can only get from food, says Matheny.
“Animal proteins have higher amounts of branched-chain amino acids in amounts that have been shown to support muscle synthesis and growth,” he says. Meanwhile, plant proteins are often lower in branched-chain amino acids or other essential amino acids.
As long as you eat a balanced diet, though, chances are you’re getting all of the aminos you need. The full nutritional picture of a food is more important than how much protein (and how many of which amino acids) it contains, says Harris-Pincus. “Your body needs a variety of foods for a variety of nutrients to prevent disease and keep you healthy all life-long,” she says. Harris-Pincus recommends mixing up your protein sources and incorporating plant proteins (like beans and whole grains) and animal proteins (like chicken and whey supplements).
Related: 7 Protein Sources For Vegetarians
Just because those plant proteins don’t pack as mean an amino acid punch, doesn’t mean they’re not valuable: Plant-based diets not only help protect the body from oxidative stress and inflammation, but also help ward off issues common later in life, like metabolic syndrome and neurodegenerative diseases, according to a review published in Trends in Food Science and Technology.
Myth #4: Eating too much protein is bad for your kidneys and bones.
Yes, protein gets processed through your kidneys. But if you have healthy kidneys and eat a balanced diet that includes a sane amount of protein, you’re not going to damage them, says Harris-Pincus. (And by ‘sane amount’, we mean Matheny’s recommendation of one gram of protein per pound of lean body weight per day, or less. Not 300 grams of protein a day.)
And what about your bones? The theory here is that eating too much protein increases the amount of acid in your body, so you pull calcium from your bones to neutralize that acid, says Harris-Pincus. But not to worry, a high-protein diet hasn’t been clearly shown to harm bone health, according to a review and meta-analysis published in Current Opinions in Lipidology. The paper’s authors suggest that a high-protein diet may actually support bone health and that healthy people should not limit their protein intake for fear of leaching calcium from their bones.
Myth #5: Protein Supplements Are The Same As Whole Food Proteins.
If you’re eating just plain, skinless chicken breast, yeah, you’re getting mostly protein—but whole food protein sources are typically a package deal, and provide protein along with other nutrients, says Matheny. (The additional vitamins and minerals are often accompanied by some fat or carbs, adding some calories to many whole food proteins.)
Protein supplements, though, are all about getting as much protein per calorie, says Matheny. And while they’re a more calorie-efficient source of protein than most animal sources (25 grams of protein from whey is about 120 calories, while 25 grams of protein from sirloin steak is up around 245), supplements shouldn’t be your only source of protein. “If you’re just getting your protein from supplements, you’re missing out on a lot of vitamins and minerals and losing the balance needed in your diet for general health,” says Matheny.
That being said, protein supplements can be hugely helpful tools. “Protein powder is great for augmenting foods that otherwise don’t provide much protein, like oatmeal,” says Harris-Pincus. A protein shake is also a portable alternative to skipping breakfast or making a desperate stop at a drive-thru.
And, since that protein shake is digested quickly, it can be especially beneficial before or after exercise, when your body needs protein quickly in order to rebuild the protein in your muscles that break down during training.