How Much Protein Is Too Much? A Dietitian Weighs In

Protein popcorn. Protein chips. Protein drinks. Protein bars. Even protein ice cream and protein candy. In one way or another, added protein has infiltrated practically every food item you'll find in most American supermarkets.

However, most Americans ages 19-59 either meet or exceed their protein recommendations, according to the Dietary Guidelines for Americans 2020-2025 edition. Men ages 19 to 59 in particular significantly exceed their protein recommendations, especially from meat, poultry and eggs — all of which are generally consumed in forms with higher amounts of saturated fat or sodium, according to the guidelines.

It's long been thought that you can never have too much protein, but emerging research suggests that an excess intake of protein can have real health consequences, including weight gain, stomach issues and even certain nutrient deficiencies.

We spoke with Knubian Gatlin, a registered dietitian at Houston Methodist, about how much protein you really need and the potential health risks that an excessive intake of protein may pose.

How much protein is too much?

"Whenever someone says they need a gram of protein per pound of body weight, this is where people start to experience some of the common side effects of eating too much protein, like constipation, bloating and stomach pain," says Gatlin. "It's very rare for a person to need that much protein, even among active adults and athletes."

Therefore, per Gatlin, any protein intake beyond a gram of protein per pound or 2.2 grams per kilogram of body weight is generally too much protein. You'll want to strike somewhere below that, but exactly where depends on a few factors.

How much protein should you actually eat in a day?

For adults ages 18 and up, the Recommended Dietary Allowance (RDA) for protein set by the Food and Nutrition Board is 0.8 grams of protein per kilogram of body weight. According to Gatlin, this recommendation is "more on the minimum side" but a person who eats this amount is "doing just fine," he says. This recommendation is typically the minimum amount a person needs to maintain their health at their current weight.

"If you're a little older or more athletic, you could increase your protein intake between 1 and 1.4 grams per kilogram of bodyweight," Gatlin says. "In some cases, protein needs can increase roughly up to 1.7 grams per kilogram, but this is most suitable for a person that engages in regular, intense resistance training. Either way, the range of 0.8 to 1.7 grams per kilogram of body weight will cover the bases for most people."

(Related: How Elite Athletes Eat to Stay Fueled and How You Can Too)

To calculate your daily recommended protein intake, simply take your body weight in pounds and divide that by 2.2. You'll then take that number and multiply it by the minimum and maximum daily gram amount of protein — 0.8 and 1.4 respectively.

Depending on your fitness level and goals, you'll want to hit somewhere on that spectrum.
For instance, an average adult weighing 200 pounds will want to eat anywhere between 73 and 127 grams of protein daily. If the person is very active and is looking to gain muscle, they may consume up to 155 grams of protein daily as the maximum recommended intake.

Don't want to do the math? Visit the USDA Dietary Reference Intakes calculator for your individual recommendations.

You'll also want to spread this protein intake throughout the day rather than in one or two meals, says Gatlin.

"50 grams or more of protein at once is not very easy on the gastrointestinal tract," says Gatlin. "Ideally, you'll want to eat about 0.35 grams per kilogram of protein per meal. That lands you within the range of about 25 to 35 grams of protein per meal. People with larger bodies or those who are very active may need a little more, roughly 38 to 40 grams, depending on their individual protein requirements."

Protein is especially important at breakfast because it not only helps you feel fuller throughout the day, it also helps to slow glucose absorption. This can help prevent spikes and dips in blood sugar, which promotes a prolonged sense of energy, says Gatlin.

"Protein, especially in the morning, gives us a chance to get that first set of building blocks in our system that we can use for tissue maintenance, repairs and everything else that takes place throughout the day within our bodies," he says. "Research suggests that people who regularly eat higher amounts of protein in the morning and spread it throughout the day tend to have increased longevity, are able to do more on their own as they go through the aging process and are going to be more efficient at maintaining their muscle mass."

(Related: 10 High-Protein Foods to Help Hit Your Macros)

What does 25 to 35 grams of protein look like?

If you're eating a balanced diet, chances are you have no problem hitting the goal of 25 to 35 grams of protein each meal. But what does a balanced diet look like on a plate? Try to achieve the following five principles of creating a balanced plate:

1. Fill half your plate with non-starchy vegetables and fruits
2. Add a quarter-plate of whole grains
3. Add a quarter-plate of lean protein (animal- or plant-based)
4. Keep saturated fats, cholesterol and added sugars to a minimum
5. Be mindful of portion sizes

Keep in mind your plate isn't always going to be divided neatly into nice and tidy sections like this, but these recommendations still apply to one-pot meals, casseroles, bowls, salads, pastas and sandwiches.

Some foods can also count for more than one type of macronutrient. For example, beans count as a starchy vegetable (carb) and a protein. A cup of cooked black beans contains 14 grams of protein and more than half of the daily recommended fiber intake. Whole grain bread, another carb, also has a good amount of protein in it. Two slices — what it takes to make a sandwich — offer 8 grams of protein and 14% of your daily fiber.

What can happen if you eat too much protein?

When it comes to eating too much protein, a big steak or chicken isn't going to cause that much of an issue if eaten every once in a while. However, when you habitually eat an excessive amount of protein daily or near daily, that's when you're more likely to experience a few of the possible side effects associated with excessive protein consumption. Those include:

Excess calories and weight gain

"When people overeat protein and undereat carbohydrates, some of the protein turns into carbs, but it's usually not enough," says Gatlin. "This promotes what muscle builders call 'the cut' (or some fat loss) due to caloric deficit but when you severely reduce your carbs and rely almost solely on protein, you'll see some progress but not for very long. Carbohydrates are a much more efficient source of energy, and as a result of protein replacing carbs for energy, your body may actually experience cravings for sweets and other carbohydrate-rich foods in response to you forcing your body to use protein as energy instead of carbs."

In addition to craving carb-rich foods, if you are piling excess protein onto your plate, you're likely eating more than you should, says Gatlin. To get more protein, you typically have to eat more than you normally would, which can risk excess calories and, eventually, weight gain.

Certain micronutrient deficiencies

"If you're eating more than the recommended amount of daily protein, you're probably relying on some sort of animal product, whether it be meat, eggs or dairy," says Gatlin. "While those products are totally fine in moderation, if you're not eating enough plant-based foods alongside these items, you're missing out on many of the phytochemicals, pigments, fiber and antioxidants that are abundant in plants and not so much in animals."

This is a known risk among fad diets like the ketogenic (keto) dietand carnivore diet that prioritize protein and fat-rich foods over carbohydrate-rich ones, like fruits, whole grains and starchy vegetables that are very beneficial to our health but are largely excluded from these types of restrictive eating patterns.

A deficiency in any essential nutrient like magnesium, potassium, Vitamin C and folate that the body cannot make itself has the potential to cause health problems.

Gastrointestinal distress

As Gatlin mentioned, if you're eating too much protein, chances are you're not eating enough fiber to support healthy digestion of those foods. In turn, this combination of excess protein and lack of fiber creates a "double whammy" effect on your stomach, resulting in symptoms ranging from both constipation and diarrhea to bloating, gas and stomach pain.

"I'd be a little mindful of how much animal-based foods I'm eating and what I'm eating them with. For example, fiber helps slow and lower the absorption of cholesterol and excess salt, which are often found in abundance among animal-based foods, especially red meat, processed meats and full-fat dairy," Gatlin says.

The problem is most of us don't get enough fiber, says Gatlin — not near enough. Research suggests only 5 percent of men and 9 percent of women in the U.S. meet their recommended daily fiber intake.

Adverse cardiovascular outcomes

In addition to stomach issues and potential nutrient deficiencies, an overconsumption of protein, especially if it's from meat and dairy, can also take a toll on your heart health, Gatlin says.

Numerous studies have shown a diet rich in meat — specifically red meats like beef, pork and lamb — has been linked to an increased risk of heart disease, stroke and early death. Eating too much saturated fat can raise bad cholesterol and increase your risk of heart attack and stroke, per the American Heart Association.

Fiber, in addition to helping ease the GI issues associated with overeating protein, also helps to slow the absorption of cholesterol and sodium from the gut, says Gatlin. You'll need to drink enough water, however, to ensure that the fiber actually performs its function, says Gatlin. Otherwise, you risk the same exact symptoms as excess protein intake like gas, bloating and constipation.

"Rather than trying to eat more protein beyond 1.7 grams per kilogram, I think people should be more concerned about more fiber intake, more water, more sleep and less stress," he says. "This is one of the secrets to life."

(Related: 7 Benefits of Fiber That Should Convince You to Eat Enough of It)