Depending on who you ask, we’re either eating “too much” protein, or we need protein shake after protein shake just to build a little muscle or lose weight. The truth isn’t either of these. Some of us may need more, while others get more than enough—but more isn’t necessarily harmful. Here’s how to figure it all out.
More Than Enough Isn’t “Too Much”
Last time we talked about protein, we were trying to figure out how much was enough. To recap, the Health and Medicine Division of the National Academies says that 98 percent of us will get enough protein if we eat 0.36 grams of protein per pound of body weight. That number, the RDA, is the basis of textbook and government guidelines. It works out to 54 grams for the average woman, who is about 150 pounds, or 72 grams for the average man at about 200 pounds.
Most Americans eat more than that. In this report from the US Department of Agriculture, based on a large survey from 2010, men ate 98 grams of protein per day, on average and women ate 68. Protein intake was low in some older adults and some teenage girls, but most of us easily meet the textbook requirements.
Studies like that one have led to a sort-of myth that we are all eating “too much” protein. But that’s misleading. It’s more correct to say that on average we are eating more than enough protein. That’s a good thing! After all, we wouldn’t want to eat less than enough.
So that number we started with—0.36 grams of protein per pound of bodyweight, sometimes written as 0.8 grams per kilogram—is a minimum. And it’s only the minimum for people living an averagely sedentary life. If you exercise a lot, or if you’re trying to lose weight, it makes sense to eat more than that.
Even if a marathon runner or a bodybuilder would be healthy with a protein intake near the textbook amount, they may be even healthier, or able to do better in their sport, with a higher intake. Again, that’s not too much; it’s within the range that their body can put to good use. This range goes up to 0.82 g/lb, depending on the athlete and their sport. That’s 123 grams for a 150-pound person, or 164 grams for a 200-pound person.
Extra Protein Just Means Extra Calories
You’ll notice that even the higher levels we discussed are well under the 1 gram per pound “rule” that bodybuilders and some other athletes like to repeat. You don’t have to look far to find people who are trying to eat 200 or even 300 grams of protein in a day, on the theory that more is better. The extra protein won’t hurt you, but it could make you gain weight.
Here’s what’s going on in your body. We eat protein so that we have amino acids (protein’s building blocks) to build our own protein-containing body parts. That includes muscle as well as hair, skin, enzymes, and all kinds of little components of our cells. But we only need so much. Eating an extra 100 grams of protein won’t make your body decide to build 100 more grams of muscle and hair. Instead, that extra protein is just…food.
Just like we can burn fat or carbohydrates as fuel, we can burn protein. And just like we can convert those nutrients to fat for storage, we can do that with protein too. To burn or store protein’s calories, our body has to remove the nitrogen-containing “amino” part from each amino acid, and the most convenient way to excrete that nitrogen is in urine. That’s given rise to a bizarre myth that it’s impossible to eat too much protein because your body will “pee out the excess.” No, the calories from the protein are still being stored or burned like any other calories. Your pee just contains an indicator of the fact that you ate some of your calories in the form of protein.
That’s disappointing if you’re trying to lose weight: you could have had those same calories in a different form that maybe you liked better. Perhaps a grilled cheese or a small dessert instead of an umpteenth dry chicken breast.
The “Dangers” of High Protein Diets Are Overblown
The same government document that lays out the recommendations for protein also contains a note about the “adverse effects of excessive consumption.” There is no level of protein, it says, that is associated with adverse effects. Instead, they recommend that protein make up between 10 and 35 percent of adults’ calories. They chose the lower number to provide enough protein to meet the RDA, and the upper number is, basically, as much protein as you can eat while still getting the recommended fat and carbohydrate.
So if the National Academies don’t think high protein intakes are dangerous, who does? Mainly people who aren’t up on the science, and groups like the pro-vegetarian Physicians’ Committee for Responsible Medicine. They list kidney disease, cancer, and kidney stones as downsides of a high protein diet.
But we need to remember that protein is not the same thing as meat. High intake of red and processed meat is linked with cancer, but that’s no reason to avoid other protein sources like chicken, tofu, beans, or whey powder. The connection with kidney stones is iffy, too: animal protein seems to be linked with stones, but the American College of Physicians couldn’t find enough evidence to recommend low protein diets for people prone to stones.
And the idea that too much protein will “place a strain on your kidneys,” as the PCRM says, has also been debunked. As Chris Kresser points out, people who have donated a kidney aren’t at risk for kidney disease, even though their remaining kidney is working twice as hard. That makes the “strain” idea a tough sell. Low protein diets do help people who already have kidney disease, but there isn’t any evidence that high protein is harmful for people who have healthy kidneys to start with.
Find Your Sweet Spot
Since there’s no strict limit on protein for healthy people, you need to find out what is the right amount of protein for you. Use your activity level and goals to figure out what your minimum should be. That’s your “enough.” Track what you eat to make sure you’re getting an amount close to that. Tracking is especially helpful if you’re on a restrictive diet, whether paleo or vegan or just very low calorie, since you might not realize what you’re missing.
Then, to find your personal “too much,” look at your calories. Does 300 grams of protein (that’s 1200 calories) really fit into your diet? If you truly love the taste of tuna and protein shakes, it’s not our business if you pig out. But if a high protein diet is more trouble and more calories than it’s worth, that’s when it becomes too much.