Can Too Much Protein Cause Constipation? (From a Dietitian)

James Cunningham, BSc, CPT
Published by James Cunningham, BSc, CPT | Staff Writer & Senior Coach
Last updated: June 21, 2024
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A high-protein diet is great for keeping you in shape, but if you feel stuffed up lately, chances are you’re eating too much protein.

Excess protein may cause digestive issues, including constipation, and may have other adverse effects, too.

So, through in-depth research, let us find out whether high-protein consumption causes constipation and how you can avoid it.

Quick Summary

  • High-protein diets can shape your body but may lead to constipation due to reduced fiber intake.
  • To prevent constipation on a high-protein diet, balance it with high-fiber foods like non-starchy vegetables and increase fluid intake.
  • According to the American Dietetic Association, adults should aim for a daily fiber intake of 25 grams for women and 38 grams for men to support digestive health, especially if their diet is protein-rich.
  • In my opinion, a well-balanced diet and combining protein with adequate fiber is key to both fitness and digestive health.

Does a High-Protein Diet Cause Constipation?

man seated down holding his bellyache

Yes, a high-protein diet can cause constipation, but it is not the protein but the lack of fiber in your diet that is directly causing it.

As a seasoned fitness coach collaborating closely with nutritionists, I've seen firsthand the crucial role of fiber in diet. Insoluble fiber, especially, absorbs water and aids digestion, a fact consistently confirmed in our joint dietary studies with clients.

According to a study published by the National Institute on Aging (NIA), not eating enough high-fiber foods such as vegetables, fruits, and whole grains or eating a lot of high-fat meats, dairy products, and eggs, sweets or processed foods may cause constipation [1].

A study published by the National Institutes of Health (NIH) states that an intake of protein above the recommended dietary allowance may cause adverse effects associated with constipation [2].

Then, it sweeps through our bowels, carrying everything out. It also adds weight and softens our stool to push it easily out of our bodies.

“Fiber helps stabilize transit time – how fast the food moves through the digestive tract.”

– Dr. Joanne L. Slavin, Professor of Food Science & Nutrition at the University of Minnesota

Ways To Avoid Protein-Related Constipation

bowl of kale, and a plate filled with spinach

If you’re currently on a high-protein diet and want to prevent constipation, your best bet is to keep your meals balanced.

  • Include non-starchy vegetables such as dark leafy greens vegetables: kale, spinach, Asian greens, cabbage. They are low in carbs and high in fiber.
  • Balance your animal protein intake with plant-based proteins such as lentils, peanuts, kidney beans, and almonds.
  • Check the protein shakes you consume. Although they normally don’t cause constipation, consuming large amounts or components such as lactose or gluten may cause digestive issues.
  • Drink more fluids.

Remedies for Constipation

woman chugging a drink of water, man warming up in a field

Constipation may cause fatigue over time so, here are things you can do when you are constipated.

1. Increase your fiber intake

Enough fiber is the key to healthy bowel movements. So, make sure you eat more fiber in your diet, especially insoluble fiber found in wholegrain foods, root vegetables, beans, pulses, and lentils (also high in soluble fiber).

2. Drink more water

Increasing your water intake helps soften stool and move it easily through the GI tract, relieving constipation. Carrying around a water bottle ensures you drink plenty of it.

3. Exercise

Doing a digestion-friendly exercise, such as a 15-minute walk or jog an hour after you had your meal, helps relieve constipation because it improves your blood flow.

Related: Yoga Poses for Constipation

4. Eat probiotic foods

Probiotic foods contain “good” bacteria that are safe and help improve bowel movements and soften hard stools.

What's a Normal Protein Intake?

glass and pitcher of milk, and a tray filled with food filled with protein

The right amount of protein to take depends on several factors such as your body weight, age, gender, activity, health, and total diet.

According to insights from Healthline, the recommended dietary allowance (RDA) is 0.36 grams of protein per pound (0.8 grams per kg) of your body mass [3].

It’s about 56 grams per day for an average man with an inactive lifestyle (not exercising) and an estimated 46 grams per day for an average woman with an inactive lifestyle.

Those who have an active lifestyle, eating 1.2 to 1.7 grams per kg of body weight each day do them well.

Elite athletes need to consume more protein for weight loss and improved athletic performance. The International Journal of Sports Nutrition recommends 1.6 to 2.4 grams of protein per kg body weight per day.

If you are looking to add a protein supplement to your diet, make sure you check out our article on the best whey protein powders on the market.

What Are the Side Effects of Too Much Protein?

Man experiencing stomach pain

Our findings show that while high dietary protein intake helps in muscle building and weight management, it can also lead to issues like gaining weight, diarrhea, and even dehydration.

  • Diarrhea - Eating too many dairy products and processed food, plus a lack of fiber, may cause diarrhea.  Avoid diarrhea: limit fried foods, avoid caffeinated beverages, increase your fiber intake, and reduce excess fat consumption.
  • Weight Gain - Eating fewer carbs and consuming more protein helps you lose weight and grow muscles. However, it may lead to excess calories that are stored as fat, resulting in an increased body weight.
  • Dehydration - High-protein diets cause your kidneys to work overtime to flush out excess nitrogen found in the protein’s amino acids out of your system. As a result, you urinate a lot, feel more thirsty than usual, and worse, wreck your kidneys over time.
  • Calcium loss - Some protein sources are high in acid that binds with calcium and is excreted in the urine, resulting in loss of calcium. It is said to cause bone issues over time; however, no research proves it yet.
  • Heart Disease - Increased protein intake from red meat and full-fat dairy foods increases the risks of heart disease because they contain high saturated fat that can build up around the blood vessels. It is best to eat heart-healthy meals.
  • Risk of cancer - Eating protein in large quantities, especially those coming from red and processed meat, is linked to increased cancer risk. It is because these high-protein foods are considered carcinogenic.
  • Bad breath - As our bodies break down protein’s amino acids, they release ammonia that produces a strong odor on our breath; so, extra protein may lead to bad breath.

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About The Author

James Cunningham, BSc, CPT
Staff Writer & Senior Coach
James Cunningham, BSc, CPT holds a BSc degree in Sport & Exercise Science from University of Hertfordshire. He's a Health & Performance Coach from London that brings a unique blend of academic knowledge of health supplements and practical exercise experience to the table for his readers.
Learn more about our editorial policy
Dr. Harshi Dhingra, MBBS, MD is a published peer-reviewed author and renowned physician from India with over a decade of experience. With her MBBS from Bharati Vidyapeeth and an MD from Rajiv Gandhi University, she actively ensures the accuracy of online dietary supplement and medical information by reviewing and fact-checking health publications.
Learn more about our editorial policy
Dr. Kristy June Dayanan, BS, MD is an author with a BS degree from University of the Philippines and an MD from University of Perpetual Help System. Her ability to simplify medical science complexities and dietary supplement jargon for the average reader makes her a valued medical fact checker and reviewer.
Learn more about our editorial policy

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