Can You Eat Too Much Protein? 8 Signs You Are Overdoing It

The universal diet advice often seems to be “eat more protein,” and protein seems to be the most revered macronutrient. 

Although each of the three major macronutrients is important for your health and has a place in a well-balanced, healthy diet, there are unique physiological functions and benefits of protein that certainly make it important to eat enough of it.

However, can you eat too much protein? Does eating too much protein make you gain weight? How do you know if you are eating too much protein? Are there symptoms of too much protein to be on the lookout for?

In this article, we will discuss how much protein you should be eating, the symptoms of eating too much protein, and if eating too much protein causes weight gain.

We will cover: 

  • Is It Good to Eat a Lot of Protein?
  • Can You Eat Too Much Protein?
  • Does Protein Make You Gain Weight?
  • 8 Risks and Signs You Are Eating Too Much Protein

Let’s get started!

A variety of foods high in protein.

Is It Good to Eat a Lot of Protein?

People who are in good health and who do not have any kidney issues may benefit from following a high-protein diet.

For example, high-protein meals have been shown to confer a greater satiating effect than high-carbohydrate or high-fat meals. 

The effect of protein on fullness and decreasing appetite is thought to be due to various hormonal changes that alter metabolism after eating protein.

For example, studies suggest that eating protein causes the release of peptide hormones from the gastrointestinal tract and amino acids into the bloodstream. 

Protein ingestion also stimulates metabolic hormones that relay information about energy balance to the brain, which may help the brain determine you are full. 

Indeed, many studies have found that long-term adherence to high-protein diets does seem to decrease food intake, body weight, and body fat percentage.

A variety of high-protein foods such as fish beans and cheese.

Can You Eat Too Much Protein?

Registered dietitians and nutrition experts advise against over-consuming protein above the recommended daily amount. Much like exceeding the recommended amount of any nutrient on a chronic basis, habitually overconsuming protein can cause adverse health effects.

For example, studies show that chronic high-protein intake that exceeds 2 grams per kilogram of body weight per day for adults may cause digestive, renal, and vascular dysfunction and should be avoided.

Excessive protein intake, most notably, can cause kidney strain and can be deleterious to bone health.

Does Protein Make You Gain Weight?

Although high-protein diets can support weight loss by increasing satiety, eating too much protein can cause weight gain.

Protein contains approximately 4 kcal/gram, so if you are eating a lot of protein and putting yourself into a caloric surplus, such that you are consuming a higher number of calories per day than you are burning, you will gain weight.

Whether those excessive calories come from fat, carbohydrates, or proteins, the body will treat the energy surplus the same: the extra energy will be converted to and stored as body fat (adipose tissue).

In fact, one study found that low-carbohydrate diets that compensated for the reduction in carbohydrates by eating more proteins were particularly prone to cause weight gain, so even if you replace fat by eating more protein, weight gain is possible.

A person covering their mouth.

Risks and Signs You Are Eating Too Much Protein

#1: Bad Breath

It may sound strange, but one of the symptoms of too much protein is bad breath or halitosis. 

Evidence suggests that people on high-protein, low-carbohydrate diets do experience halitosis. This high-protein symptom is particularly prominent if you concurrently restrict carbohydrate intake.

Bad breath from eating too much protein is due to the fact that the body may shift into a state of ketosis, in which you are burning ketones for fuel since glycogen (carbohydrate) stores are minimal.

This process is associated with an ammonia-like odor, or what is described as a rotten fruit smell that, unfortunately, cannot be washed away with even the best oral hygiene (brushing your teeth regularly, flossing, chewing gum, and drinking plenty of water).

The word dehydration.

#2: Increased Urination and Dehydration

One of the risks of eating too much protein is dehydration, as one of the signs that you are eating too much protein is excessive urination.

The building blocks of protein molecules are amino acids, which are nitrogenous compounds.

The body must maintain proper nitrogen balance within a small window. 

Eating too much protein causes the level of nitrogen in your blood to increase. The reason that the kidneys get taxed with high-protein diets is that they must constantly filter and process this excess nitrogen as a toxin and excreted it from the body through the urine.

If you are peeing more frequently, it can be a sign that you are eating too much protein.

Then, dehydration can occur as a consequence of increasing urine output.

Studies have found that as protein intake in athletes increases, hydration levels decrease.

If you are going to eat a lot of protein, make sure you are drinking plenty of water.

A person holding their stomach in pain.

#3: Constipation

Depending on the composition of the rest of your diet, one of the risks of a high-protein diet is constipation. Many people who eat too much protein restrict their carbohydrate intake, which by default, decreases fiber consumption.

Fiber-rich foods, such as vegetables, fruits, whole grains, and legumes, are high in carbohydrates.

Fiber plays many essential roles in the body, particularly in terms of bulking up stool, feeding the beneficial bacteria in the gut, and promoting bowel regularity to reduce the risk of constipation.

Furthermore, there’s a large body of evidence to suggest that diets high in fiber are associated with a decreased risk of numerous diseases, including cardiovascular disease, type 2 diabetes, certain inflammatory bowel diseases, and some cancers.

Thus, if you are eating too much protein and not enough fiber, you may experience difficulty moving your bowels.

A person fatigued and tired who can not get out of bed.

#4: Diarrhea

Although constipation is one of the most common symptoms of eating too much protein, it’s also possible to experience diarrhea, depending on the sources of protein that you are eating and your sensitivities to foods.

For example, if you are lactose intolerant but are consuming a lot of yogurt, cottage cheese, or milk, you may experience diarrhea.

#5: Fatigue

A high-protein meal can be energizing, but if you are habitually overeating protein at the detriment of getting an adequate carbohydrate intake, your energy levels may suffer, and you may have difficulty focusing.

#5: Depression

One symptom of too much protein is low mood, especially if you are also consuming little fat.

According to research, high-protein, low-fat diets can increase the risk of depression.

A person holding their back where their kidneys are.

#6: Kidney Damage

The biggest risk of eating too much protein is thought to be kidney damage.

However, the good news is that there hasn’t been much scientific evidence to suggest that high-protein diets cause significant kidney damage for people in good health with no kidney disease.

However, excess protein has been shown to cause kidney impairment and further kidney damage in those with pre-existing kidney disease.

In fact, if you have kidney disease, it’s often advisable to follow a low-protein diet to avoid extra workload on the kidneys.

#7: Bone Loss

One of the consequences of eating too much protein is that excessive protein can cause bone loss, which may eventually lead to osteoporosis.

A person holding their head, depressed.

#8: Increased Risk of Diseases

Eating too much protein can potentially increase the risk of heart disease and certain cancers, primarily if the protein sources are coming from red meat, processed meats, or fatty cuts of meat.

For example, studies have found that diets high in processed meats (sausages, hot dogs, bologna, etc.) and red meat can increase the risk of certain cancers, including breast cancer, colorectal cancer, and prostate cancer.

Other studies have also confirmed that high-protein diets that are high in red meat are associated with an increased risk of cancer, cardiovascular disease, and all-cause mortality.

Similarly, studies have found that eating a lot of red meat and full-fat dairy can increase the risk of heart disease, while fish, poultry, and nuts can decrease the risk.

Therefore, according to the evidence, if you are eating a lot of protein, the protein source—and the quality of the food itself—matters.

Ultimately, most people eat far more protein than they need. The recommended daily intake of protein is 46-63 grams for most adults and up to 65 grams per day for women who are pregnant or breastfeeding. The RDI represents the nutrient requirements for 97-98% of healthy individuals.

Protein needs for athletes may be higher, but studies suggest that protein intake should not exceed a maximum of 3.5 g/kg of body weight for “well-adapted” adults and 2 g/kg of body weight for average healthy adults.

If you are looking for a well-rounded, healthy diet, check out our healthy diets for runners guide.

Blocks that spell out balanced diet with a variety of healthy foods around it.
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Amber Sayer is a Fitness, Nutrition, and Wellness Writer and Editor, and contributes to several fitness, health, and running websites and publications. She holds two Masters Degrees—one in Exercise Science and one in Prosthetics and Orthotics. As a Certified Personal Trainer and running coach for 12 years, Amber enjoys staying active and helping others do so as well. In her free time, she likes running, cycling, cooking, and tackling any type of puzzle.

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