Is Too Much Protein Bad For You? 10 Side Effects That You Should Know Of

is too much protein bad for you

High-protein diets like the Atkins and Keto diets which allow you indulge in your favorite proteins – as long as you significantly cut back on carbs – have become a popular alternative to traditional dieting. Since protein is a major building block for life it seems logical to have a diet rich in it. But is it possible to have too much protein? Are certain diseases caused by consuming excess protein? Here are some answers.

1. Leads To Stinky Breath

Ketosis is a process in which your body uses fat instead of carbs to generate energy. This can help with weight loss, which is why so many people have turned to the “Keto” diet. Unfortunately, it can also leave you with bad breath.


High protein foods set off a chemical chain of events during the body’s digestive process. Excess protein makes it difficult for the body to break them down efficiently, leaving behind excess amino acids. These amino acids combine with anaerobic bacteria in the mouth (which are also responsible for cavities and decay) to form noxious sulfur compounds that cause bad breath.1

2. Triggers Headaches, Muscle Cramps, Weakness, And The Blues

It’s important to remember that carbohydrates are necessary for energy. So if you need to power through your workout, replace your protein shake with something higher in carbs.2


If you consume too much protein and not enough carbs, you may end up with headaches, muscle cramps, or general feelings of weakness as your body adapts to burning fat for energy instead of carbohydrates.3 You may also end up feeling a little more down. A study on overweight adults in Australia found that sustained intake of fewer carbs for a year caused weight loss. However, higher protein and fat intake reduced serotonin concentration in the brain, something that could negatively affect your mood in the long run.4

3. Causes Digestive Issues

Having a protein-heavy diet often comes at the cost of fiber. Dietary fiber is important for keeping your digestive system in good working order. Excess protein without adequate fiber may cause diarrhea or constipation. Research on diets heavy on protein and low on carbs have found this to be a common side effect.5


4. Increases Risk Of Stroke And Heart Disease

A high-protein diet based on animal protein also increases your intake of saturated fats, which can be bad for your heart. For instance, if you were to eat red meat or dairy as your protein, you run the risk of raising levels of low-density lipoprotein (LDL) or bad cholesterol and increasing your risk of stroke and heart disease.6

5. Induces Weight Gain

Although it is assumed that protein builds muscle, the macronutrient can only help repair and rebuild muscles. And any protein that isn’t used for this purpose is stored as fat. Be sure to exercise to build muscle.7


Seen or heard an amazing weight-loss story from someone who has found success on a high-protein diet? While it’s tempting to follow suit, here’s what you should know before jumping on the high-protein, low-carb bandwagon.

According to the Dietary Guidelines for Americans 2010, if you’re going heavy on protein and consuming little carbs in a bid to lose weight, it may be counterproductive. Diets in which over 35 percent of calories come from protein and under 45 percent from carbohydrates are comparable to any fad diet and won’t result in lasting weight loss.


A better way to approach your diet is by balancing your intake of proteins, carbs, and fat in a more healthy manner. The U.S. Department of Agriculture and of Health and Human Services recommend that between 10–35 percent of your calories should come from protein, 45–65 percent from carbs, and 20–35 percent from fat.8

6. Worsens Liver Disease

If you already have a damaged liver, loading up on high amounts of protein can cause the buildup of harmful toxic waste products in your body. That’s because your liver is unable to process all that protein properly. Normal dietary levels of intake are fine, but when you go overboard, whether through your diet and/or with supplements or protein powders, you could cause more damage to your liver.9


7. Damages The Kidneys And Worsens Kidney Disease

There are concerns that too much protein can damage your kidneys, causing issues like kidney stones, kidney pain, or impaired kidney function. Hyperfiltration and high glomerular pressure, mechanisms that some believe are precursors to renal damage, are believed to be brought on by high-protein diets.10

Glomerular filtration rate (GFR) is an indicator of kidney function and the progression of renal disease. The more the damage to your kidneys, the lower the GFR.11 Excess protein consumption can mean different things depending on the health of your kidneys.


Can Be Problematic For Kidney Disease Patients: If your kidneys are already damaged, having a high-protein diet could be problematic. It could accelerate renal disease and stop your kidneys from functioning properly. Research on patients with advanced renal disease has also found that low-protein diets were beneficial and helped reduce the rate of decline in GFR.12

Not A Problem For Healthy Individuals: Hyperfiltration caused from a higher intake of protein is actually a normal response. It’s an adaptive mechanism for your body to respond to physiological changes and is not something to worry about in healthy individuals.13 A study on over 1,000 healthy women with normal renal function found that consuming high amounts of protein did not adversely impact kidney function.14

Certain proteins may increase cancer risk. Studies have shown that there is a possible association between the risk of breast cancer and consumption of soy protein powder. Soy isoflavones have been shown to increase the growth of breast cancer tumors in animal test subjects.15

There is also some evidence to suggest colorectal cancer risk may be linked to animal protein and animal fat intake. However, researchers say there is insufficient epidemiologic evidence to support this theory.16

Similar outcomes were noted in research that looked at renal cancer risk linked to total protein, animal protein, and fat intake. However, while positive associations were initially found, after adjusting for body mass index, alcohol intake, and fruit and vegetable intake, the results were not statistically significant.17

9. May Lead To Osteoporosis

Digesting protein also releases several acids in the bloodstream and calcium is required to neutralize them. A high protein diet may force the system to extract more calcium from the bones, weakening them over time.18

10. Triggers Dehydration

Excessive protein-intake might increase your thirst. This indicates dehydration and is caused when the body uses up extra fluids to wash out the excess nitrogen produced when digesting proteins.19

Aim At Obtaining Only 15–25 Percent Of Daily Calories From Protein

Your body needs protein not just for caloric energy but for the amino acids, which help build and preserve muscles and tissues. Proteins can come from plant sources like peas, beans, seeds, nuts, and soy, or animal foods like eggs, dairy, poultry, meat, and seafood.20

The Recommended Dietary Allowance (RDA) in the United States is 46g a day for women and 56g a day for men. More specifically, 0.8g of protein is recommended for every kilogram of body weight. So, a woman weighing 140 pounds and leading a sedentary life would need 53g of protein a day. If you compared that against daily caloric intake, you will be getting just 10 percent of your calories from protein. But then, that’s the minimum protein you should be getting.

Harvard Health experts suggest that 15 to 25 percent of your total daily calories can come from protein. And the Dietary Guidelines For Americans have even raised the upper limit to as much as 35 percent. Exactly what percentage is best for each individual will depend on a variety of things, like your physical activity level and your medical background. On average, most Americans come closer to 16 percent.21

Artificial, Processed Protein Sources Have Side-Effects

Whether you’re consuming animal products, plant proteins, powders, or supplements, not all proteins are the same – and some varieties of protein lead to specific side effects. Here’s the best way to boost your protein.

Choose Dietary Sources Of Protein Over Powders And Supplements

It is better to consume your protein through dietary sources than through protein powders and other supplements. These powders have a host of possible side effects:

  • Pea protein powder can lead to flatulence or intestinal discomfort.22
  • Soy protein powder can disrupt endocrine regulation and modulation by the body.23
  • Artificial sweeteners in powders can leave you with an upset stomach.24 and disrupt gut flora.25

If you are very active or are trying to build muscle, avoid overdoing the protein powders and balance your consumption with healthy proteins in your diet.

Animal Protein Is Best To Avoid With Kidney Disease

One study found that consumption of non-dairy animal protein in particular causes acceleration in the rate of decline of renal function in women who already had mild renal insufficiency.26

The Best Protein Sources For Your Heart

For a healthy heart, opt for low-fat, non-animal, non-dairy plant proteins, like what you get from legumes, beans, nuts, and lentils. Among animal proteins, choose those low in saturated fats like poultry or, even better, fatty fish like tuna or salmon, which is also rich in health-boosting omega-3 fatty acids.27