Key Points
Eating the right amount of protein is essential for supporting your body’s functions, including metabolism, immunity, and muscle health.Consuming too much protein can lead to digestive issues, weight gain, and displacing other important nutrients like fiber.Excessive protein intake, especially from high-fat animal sources, may increase the risk of liver strain, kidney stress, and heart disease.

It seems impossible to explore the nutrition space without hearing about protein. Home cooks are adding cottage cheese and yogurt to nearly every dish, while manufacturers are making protein-rich versions of their popular products. As a result, you might feel inspired to optimize your protein intake during every meal. But is it really necessary? To find out, we asked registered dietitians to explain the ins and outs of protein requirements, plus what can happen if you eat too much. 

Why Protein Is Important

If you’re wondering why everyone is so obsessed with protein, consider this: Nearly everything that happens in the body requires protein, says registered dietitian Maddie Pasquariello, MS, RDN. For example, it’s involved in regulating organ systems, maintaining immunity and metabolism, and ensuring the function of hormones and neurotransmitters, Pasquariello says. “It is also vital for maintaining a healthy body weight and the health of muscles and bones.” 

How Much Protein Do You Need?

The Recommended Dietary Allowance (RDA) for protein is 0.8 grams per kilogram of body weight, says registered dietitian Christy Maloney, RD, LDN, CEDS-C. In the U.S., most people meet this minimum requirement. But if you’re active, practicing resistance training, and/or trying to lose weight, you’ll generally need more—about 1.2 to 1.8 grams of protein per kilogram of bodyweight. Otherwise, any intakes higher than this range aren’t required (or recommended) outside of specific clinical situations, says Pasquariello.

How Much Protein Is Too Much?

Since everyone has different protein needs, consulting a dietitian is the only way to know how much is too much. They can precisely calculate your needs based on your activity level, workouts, and goals, says Pasquariello.

“But generally speaking, between 1.2 to 1.6 grams [of] protein per kilogram body weight per day is plenty for the average active person who practices resistance training and is looking to gain muscle, potentially while losing fat,” says Pasquariello. “Technically speaking, the body will use all of the protein you give it.”

There also isn’t a “limit” to how much protein you can absorb from a given meal. However, your intake will determine how protein is used in the body, and there can be side effects of consuming too much, Pasquariello says.

What Happens When You Eat Too Much Protein

These are the possible complications of overdoing protein, according to dietitians.

Digestive Issues

For some people, a high protein intake can lead to constipation, bloating, and other digestive side effects, says Pasquariello. This is especially likely if you dramatically increase your protein intake overnight. “For instance, if you include a lot of excess protein at a given meal, you’re not going to feel great because you’re likely overeating to begin with,” says Pasquariello.

Unwanted Weight Gain

“Chronically high protein consumption can lead to excess total calories, which the body stores as fat through a process called de novo lipogenesis,” says Maloney. This side effect, which happens in the liver, may lead to unwanted weight gain.

Lower Intake of Nutrients

When too much emphasis is placed on protein, it can displace other nutritious foods like fruits, vegetables, and whole grains. “For instance, if you focus primarily on protein and simple carbs, you’re likely not getting much by way of fiber,” says Pasquariello. This is worth noting because high fiber intakes are associated with a lower risk of certain cancers and cardiovascular disease, as well as better gut health, she says.

High Saturated Fat Intake

Some of the highest sources of protein are animal products. However, many of these options are also high in saturated fat. Over time, a high intake of saturated fat can lead to metabolic conditions, cardiovascular conditions, and unwanted weight gain, says Pasquariello. (To alleviate this potential side effect, prioritize plant-based and lean protein sources when increasing your protein intake.)

Liver Strain

“Eating too much protein over time can put extra strain on the liver, which is responsible for converting protein into either glucose or fat, depending on the body’s needs,” says Maloney. This added burden can result in elevated levels of certain liver enzymes, which are markers of liver stress, she notes. Without medical attention, this can lead to fatigue and inflammation, Maloney says.

Kidney Problems in Certain Groups

“While research has shown that high protein intake does not cause kidney disease in healthy individuals, it can accelerate decline in those already living with chronic kidney disease or diabetes,” says Maloney. Basically, when you consume protein, your body produces urea, a byproduct that must be filtered and excreted by the kidneys, she explains. “For someone with already compromised kidney function, this added burden can cause further damage over time,” Maloney says.

The Source of Protein Matters

Yes, getting enough protein is important. But it’s even more important to consider where your protein is coming from.

“We should focus more on lean protein sources so that we can meet our protein needs without increasing saturated fat intake in the process,” says Maloney. “Having too much saturated fat in the form of high-fat meats or [full-fat] dairy increases the risk of cardiovascular disease long term,” she adds.

Pasquariello agrees, noting that it’s recommended to get more protein from lean and plant-based sources, rather than fattier processed meats and cheeses. Otherwise, “there is no reason to eat above your body’s protein needs for a long period of time simply for the sake of doing so,” says Pasquariello.