Is it possible to have too much protein?

Protein is one of the basic building blocks of the human body, essential for building and repairing muscles. If you are interested gaining muscle and/or fat loss, you probably know how important this is increase your daily income of this macronutrient. However, there is an upper limit how much you should consume? How much protein is considered too much?

There are guardrails, but it’s hard to overdo it. Here’s what the experts say.

Are high protein diets safe?

First, it is very difficult to eat so much protein that it negatively affects your health. According to a study published in American Journal of Clinical Nutritionconsumed by the average American less than half of what is widely considered the “upper limit” of protein consumption: 35 percent of daily calories.

However, studies suggest that active people exceeding this upper limit may still experience no adverse effects. In a 2016 study published in Journal of Nutrition and Metabolism14 healthy endurance-trained men alternated between eating their normal diet and a “high-protein diet” (more than 3 grams per kilogram of body weight per day) for months. To put that into context, a 154-pound person would need to eat more than 210 grams of protein per day on this diet, which is the equivalent of almost two pounds of chicken.

After following the subjects for a year, the researchers found “no harmful effects on blood lipid measurements, as well as liver and kidney function,” which is where most adverse reactions to the protein would occur.

In addition, there is research suggests that current recommendations may be too low for certain populations, including adults over age 65, pregnant and lactating women, and healthy children older than 3 years. So while the scientific debate about how much protein is too much continues, it’s important to note the emerging literature that confirms the safety and efficacy of high-protein diets for those who require more.

3 effects associated with high protein diets

While studies have examined the potential risks of too much protein, the Dietary Reference Intakes by the Institute of Medicine states that there is “insufficient data” to provide causal relationships between proteins and health complications, emphasizing the need for controlled clinical trials.

1. Stomach upset/discomfort

Some people may experience gastrointestinal problems resulting from protein supplementation. This may be due to the lactose content of certain protein shakes, such as those containing whey protein concentrate. In these cases, the use of whey protein isolate or plant-based protein are less likely to lead to these problems because they contain less lactose than whey protein concentrate or none at all.

Potential GI issues can also come from whole foods. “If you eat too much animal protein and not enough complex carbohydrateswhich contain fiberyou may experience mild constipation,” explains Quyen Vu, MS, RDN.

2. Kidney problems

Some studies reported an association between a high-protein diet and kidney function. However, it is “extremely rare” for exercisers to develop kidney problems or other metabolic disorders due to high protein consumption, he says Glenn Gaesser, PhD, FACSMprofessor of exercise physiology at Arizona State University.

3. Heart problems

Some research suggests that excessive protein consumption can affect the cardiovascular system.

“Several population-based cohort studies suggest a higher risk of premature mortality associated with high-protein diets such as classical low carbohydrate dietwhich has a lot more protein than the typical American diet,” says Gaesser.

However, he continues: “Higher protein intake may not be the problem per se, but rather other characteristics of the diet, such as high animal fat and low foods rich in fiber.”

Can too much protein affect weight loss?

In a word, yes. Protein is a source of calories. If your goal is to lose weight, it is important to create a caloric deficita condition in which you burn more calories than you take in. If you eat so much protein that it narrows (or wipes out) your calorie deficit, it can undermine weight loss.

“Protein that is not used for the body’s usual growth and maintenance functions can be used for energy if there is a shortage from other sources and can be turned into fat,” he says Mindy Haar, Ph.D., RDN, CDN, FANDregistered dietitian nutritionist and assistant dean at the New York Institute of Technology’s School of Health Professions. “If eating too much protein causes you to eat more calories than you need, you’ll gain weight.”

However, protein is still an integral part of most weight loss efforts. A meta-analysis of 24 studies found that calorie-restricted, high-protein diets produced more positive changes in total body composition than a standard protein diet. This is likely because protein promotes fullness and can help preserve muscle.

How do you know if you’re eating too much protein?

Your first clue will likely be a stomach ache or other minor gastrointestinal drama. Even if you’re brave, know that it’s possible to eat more protein than you can efficiently process.

“Your body can only use a certain amount of protein in one sitting — about 30 grams,” he says Lisa Moskovitz, RD, CDNCEO of New York Nutrition Group. “That’s equivalent to about four ounces of cooked chicken breast or cooked fish, one cup of Greek yogurt, or two cups of black beans.”

It is also important to spread your protein intake throughout the day because the body does not store excess protein.

“In my practice, I see a lot of athletes trying to pack their protein intake into one or several meals,” he says Maddi Osburn, RDN, LDregistered dietitian in Wichita, Kansas. “If an athlete consumes too much protein in one or two meals, they will not have the most optimal response to muscle growth and will either be excreted or stored as fat. In addition, consuming too much protein could crowd out other important nutrients – e.g carbohydrates, fatand fiber – which are equally important for optimal recovery and performance.”