Protein Power Play or Nay — 5 Reasons Eating Too Much Protein Could Be a Bad Idea

March 18, 2024

woman eating

“Balance your belly.”

“Everything in moderation.”

This is how some parents explain healthy eating to toddlers and school-age children. It’s sound advice and makes perfect sense. So why are American adults tipping their dietary scales and eating so much protein? And is trendy protein loading bad for your health?

Bettina Mittendorfer, PhD
Bettina Mittendorfer, PhD

To find out, we talked with Bettina Mittendorfer, PhD, director of the NextGen Precision Health Clinical and Translational Science Unit, which uses research to bring personalized medicine to MU Health Care patients. She explains that protein is essential to your body’s function. It can also help you gain and retain muscle. But there’s a limit to how much protein you should eat.

“Many people think they can eat as much protein as they like without any consequence,” Dr. Mittendorfer says. “But it’s better to take a Goldilocks approach to protein by choosing to be in the range between what’s essential and what’s detrimental.”

How Much Protein Should You Eat?

The Recommended Dietary Allowance (RDA) sets the daily minimum amount that you should eat of a food group to meet your body’s nutritional needs. The RDA for protein is 0.8 grams of protein per kilogram (g/kg) of body weight — roughly 0.36 grams of protein per pound of body weight. That formula is based on a healthy adult who is only minimally physically active.

“The benchmark is around 60 grams per day, which is not a whole lot, but it’s been proven over and over again to be sufficient for the vast majority of people,” says Dr. Mittendorfer.

But there may be exceptions to that rule — especially if you live a more active lifestyle, are pregnant or have chronic health conditions. (Remember — the RDA is the minimum amount recommended for the body’s nutritional needs.)

For physically active adults, the Academy of Nutrition and Dietetics, Dietitians of Canada and the American College of Medicine jointly recommend 1.2 to 2.0 g/kg of body weight. Anything over 2.0 g/kg of body weight daily is considered chronic high protein intake.

“Someone who is obese could potentially be overeating protein based on the RDA formula, and someone who is super fit and active may need more than the RDA,” Dr. Mittendorfer adds.

The U.S. Department of Agriculture offers a Dietary Reference Intake (DRI) calculator that provides RDAs according to your age, weight and activity level. But your best bet is to consult your doctor who can identify a healthy protein goal specific to you and your health.

Can You Eat Too Much Protein?

The short answer is yes. But don’t panic if you occasionally overdo it (looking at you Fourth of July BBQ…).

Your dietary pattern is more important than a specific number on a specific day. If that pattern involves consistently eating very high amounts of protein, it may start to affect your health.

Dr. Mittendorfer shares five reasons why you should eat protein in moderation:

1. Too much protein can cause health issues

Experts have long known that eating too much red meat — and its saturated fat — is bad for your health. But Dr. Mittendorfer says that newer studies show a strong relationship between all types of protein and chronic health conditions, even protein without saturated fat. “There’s a trade-off with protein,” she says. “You gain all the benefits from protein up to a certain point. But if you continuously cross that threshold, you may have adverse health effects.”

Overeating protein regularly may lead to conditions such as:

2. There’s no benefit to overeating protein

Research shows that when you eat protein — up to the recommended daily intake — there’s a direct relationship between the protein you consume and the protein your body uses to repair cells, maintain bones and build muscle. But the benefits stop once your body has filled its protein quota.

“Eating more than the RDA or eating more than 25 grams of protein per meal (assuming three meals a day) doesn’t offer any further benefit,” Dr. Mittendorfer says. “You can only build so much lean muscle mass with protein. You reap the maximum benefits, but beyond that, you can potentially have adverse effects.”

3. Excess protein can turn into fat and may cause weight gain

Your body can store endless amounts of fat. But it can’t store extra protein — at least not in a usable form.

“When you eat more protein than your body can process, it lingers until it’s ultimately turned into fat,” Dr. Mittendorfer says.

Eating a high-protein diet helps you burn more calories than eating a diet high in carbs. But if you eat so much protein that you’re getting more calories than you need, you’ll gain weight. No matter what food they come from, extra calories get stored as fat.

4. If you eat a balanced diet, you shouldn’t have to add protein

A Western or American diet typically includes many sources of protein, such as:

  • Eggs
  • Lean beef and poultry
  • Nuts and seeds
  • Seafood

Even a vegan or vegetarian diet likely includes plenty of plant-based protein from foods such as:

  • Beans
  • Nuts
  • Seeds
  • Soy products

“The idea that we need to enrich a balanced, Western diet with protein is not supported by data,” Dr. Mittendorfer says. “The American population is not deficient — 80% eat the RDA of protein or more.”

Supplements and enriched foods certainly have benefits — adding vitamin D to milk reduces rickets (weak bones in children) and decreases vitamin deficiencies for example. The problem, says Dr. Mittendorfer, is that we are now adding protein to foods that don’t naturally contain it, such as water, chips and cereal. “When so much of what you eat is enriched with protein,” she says, “it becomes very tough to control or know how much protein you eat.”

5. Not all protein is created equal

Efforts to eat a high-protein diet may have you grabbing protein wherever you can find it. But the source of your protein matters. Different types of protein fulfill different bodily needs — and NextGen Precision Health researchers are working to understand exactly how each source of protein affects the body.

“The composition of each protein is different,” Dr. Mittendorfer says. “There are a lot of factors influencing each protein’s biological effect.”

She recommends you look at the other risks and benefits of protein sources. Plant-based proteins provide phytochemicals, which can help with immune and brain function and cancer prevention. But if all your protein comes from red or processed meat, you should consider the possible negative health effects of those products.

“Balance in your diet will bring you the best benefit,” Dr. Mittendorfer says, “both in the type and amount of protein you eat.”

Next Steps and Useful Resources



Read more stories like this

Deep Dive