Health
Looking to build muscle? Lose weight? Need more protein, right? Probably not.

Forget influencers, nutritionist says. Here’s how much you really need, why too much can actually hurt you

Samantha Laine Perfas

Harvard Staff Writer

November 25, 2025 8 min read

High-protein diets are having a moment — maybe too much so. Recommended by influencers and athletes, these diets suggest that upping your intake can help build muscle, promote weight loss, and even regulate your hormones.

Marc O’Meara, a senior nutritionist in the Nutrition and Wellness Service at the Brigham and Women’s Outpatient Department, said that while there are health benefits to protein, it’s important to recognize there can be too much of a good thing.

In this edited interview with the Gazette, O’Meara discusses how much you really need and when enough is enough.

Why are so many drawn to high-protein diets?

Protein is important for health and wellness, and it is an important part of weight loss. It’s the one part of any meal that tells your brain that you’re full. It makes us feel full longer.

It also controls our blood sugars. You can think of protein as setting up a dam at the end of your digestive tract, holding back any sugars that you ate. They’re slowed down and enter the bloodstream over several hours, giving us more hours to burn through those calories.

A lot of social media content has to do with muscle building.

You do need protein for building muscle, but social media has taken that and just added lots of extras on top of what the recommendations are. I often see a recommendation to eat 200 grams of protein every single day, which is way over what most people need.

Recently, I’ve had clients who were shooting for that and their kidneys were negatively affected. Your kidneys process all the extra nitrogen from the protein, and when you’re eating 200 grams a day, sometimes they just can’t keep up and they get stressed.

“You do need protein for building muscle, but social media has taken that and just added lots of extras on top of what the recommendations are.”

Marc O’Meara

Could you talk a little bit more about the consequences of over consuming protein?

Beyond negatively affecting the kidneys, protein is high in calories. I have clients who eat large protein portions at their meals, and they’re not losing weight like they hoped. They heard, “Oh, protein’s good for weight loss,” but too much will still turn to fat.

Protein is way higher in calories than vegetables — about six times more for the same volume of food. That’s a lot of extra calories that you have to burn.

How much protein do we actually need?

A general rule of thumb I give is to use your body weight (in pounds) times 0.36 (for the lower end) and 0.45 (for the higher end) and the resulting number would be grams of protein per day. For example, a 110-pound woman would need right around 45 grams of protein per day.

Another trick is to use the palm of your hand as a reference for how big a portion of chicken or fish should be at your meal. That would be about 20 to 25 grams of protein. So if she just ate two portions like that in a day, maybe an egg in the morning, a light protein snack, she’s already around 60 grams.

Some people go a little bit above the goals, and that’s OK, but if you’re doubling or tripling the recommendation, that’s where kidneys start to fight back.

Does the recommendation change if you’re an athlete or someone with a high level of physical activity?

Yes, there should definitely be an increase in protein consumption. But the increase in protein isn’t quite as much as people often think. It might be an additional 50 percent from that baseline calculation.

That same 110-pound female, if she was an athlete, I’d add an additional 20-25 grams of protein to her diet. If you’re someone who regularly does intense workouts and your goal is to build muscle or get toned, you would fit in that same category.

Another group of people that have different protein needs are women who are pregnant or breastfeeding. What recommendation would you give them?

They need more too, because they’re literally feeding another human. Generally, I’d recommend about 1.25 times the baseline recommendation for pregnant or breastfeeding women (which is also the recommendation for elderly populations).

I take care of a lot of pregnant women who have twins at the hospital, and most of them fall in the range of needing about 100 grams per day. They’re trying to get 50 grams for themselves, then an additional 25 grams for each fetus.

Say a little more about elderly populations.

The over-age-65 group often gets overlooked in protein conversations. But protein helps them stay strong, prevents falls, and keeps the muscles and bones healthy.

A lot of us start losing muscle mass after the age of 40 so strength training is important. You can’t just add muscle by eating more protein. You also need strength training, at least two to three times a week.

Protein can be sourced from both animals and plants. Does it make a difference?

The Nurses’ Health Study had a paper come out that showed that people who were mainly eating protein from beans, nuts, and dairy products had much lower risk of chronic diseases during the rest of their life. That seems like it’s a good thing.

You get a lot of nutrients in addition to the protein when you eat certain plants, like fiber, phytonutrients, vitamins, and minerals. Many animal proteins don’t have those. Also, some studies show plant protein is easier on the kidneys.

I hear a lot from like my patients that their doctors want them to eat a more plant-based diet, but they’re concerned about protein. It’s just a matter of focusing on the foods that have plant proteins and trying to get the right amounts.

Some just can’t do it, so they might have a protein shake. The key thing there is to avoid the brands that have heavy metals in them, especially if you’re pregnant.

What are your thoughts on the protein products? Yes, there are shakes, but there are also other products like bars, snacks, or even cookies that claim to be high in protein.

There are some products that are highly processed with many added, fake ingredients.

My patient showed me a protein bar recently, and I looked at it and was like, “Oh my gosh. I’ve never seen a protein bar that had four different sugar substitutes in it.” But it was marketed as a keto bar with no carbs in it.

Protein is the hot thing right now so food companies are just marketing around that. I was a nutritionist in the ’90s during the “fat free” decade, and it was the same thing. A lot of those products got axed during the 2000s because we realized that eating fat free wasn’t healthy either.

We’d rather have our clients eating more Mediterranean style with healthy fats. We at the Brigham always encourage our clients to cook more, use all natural foods as much as possible, and try to steer away from processed foods.

What if you’re crunched for time?

Try to choose foods that have balance. There are some brands of protein bars that have a really good balance of protein and carbs.

It’s like if you had a piece of chicken and a serving of rice: If they’re the same size on the plate visually, that’s what we would recommend. So choose a bar or shake that has real food ingredients and a balance of carbs and protein.

What are your top recommendations for folks who want to shift their diet to more appropriately incorporate protein?

Eat some protein every single time you eat. Whether it’s a meal or snack, protein needs to be a part of it.

And the order you eat your food does matter.

Have your vegetables or salad first; that gives you volume in your belly so you feel full. Then eat your protein; that signals fullness to your brain and sets up that dam to slow everything down. And the carb or sugar comes last for the best blood sugar control.

Another tip: Some of my clients love to eat desserts. You really want to have them right at the end of your meal so the protein can help moderate the sugar.

If you wait until 9:30 p.m. when you’re watching TV, then all the protein from dinner is gone, digested, and processed. There’s no more wall, so you’ll see a sugar spike that can turn into fat while you sleep.