Can Too Much Protein Cause Constipation? A Dietitian Explains the Link
Key takeaways:
A high-protein diet can cause constipation if it’s low in fiber-containing foods.
A well-planned high-protein diet that contains fiber-rich foods like vegetables, whole grains, and legumes can help promote regularity.
Drinking enough fluids and getting enough physical activity also help with constipation.
Table of contents
High-protein diets are popular for weight loss and blood sugar management. But high-protein diets are often low in nutritious carbohydrates that contain fiber, such as whole grains, fruits, and legumes. These fiber-rich foods help ensure regular bowel movements.
So, while protein itself doesn't cause constipation, not getting enough fiber does. The good news is that you can eat a high-protein diet and still get adequate fiber.
Here are some tips to help ensure regular poops — even when you eat a diet that’s high in protein.
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What is constipation?
Technically speaking, constipation is when you have fewer than three bowel movements in a week. But even if you have more than that, you might still be constipated. Especially if your stools are hard, dry, and/or difficult to pass. It may be painful to go to the bathroom. Or you might feel like you haven’t emptied your bowels completely.
There are many causes of constipation. It can be related to different lifestyle routines, a side effect of medication, a medical condition, or stress.
But often, constipation is a result of poor diet. The most common dietary issues are low intake of both fiber and fluids. Not getting enough physical activity and drinking too much alcohol may also play a role.
Can too much protein make it hard to poop?
It’s more likely a lack of fiber that makes it difficult to poop, rather than too much protein.
Many high-protein diets are high in animal-based foods, which don’t contain any fiber. These foods include:
Meat
Poultry
Fish and seafood
Eggs
Milk
Yogurt
Cheese
How often should you poop? What’s normal varies from person to person, but when you poop, your stool should be soft, formed, and easy to pass.
Why is fiber so important? Yes, fiber keeps your poops regular. But it also helps your overall health by improving cholesterol, blood sugar, and weight, among other things.
The highest-fiber fruits: Avocados, raspberries, and guava are just a few of the fruits loaded with fiber — plus plenty of other nutrients for overall health.
If you eat a high-protein diet that leans largely on these foods, you may crowd out space for fiber in your diet.
And, as mentioned above, some high-protein diets intentionally limit carbohydrates. High-protein/low-carbohydrate diets are popular. But when you increase protein and cut back on carbohydrates, your fiber intake likely decreases, too.
If you don’t get enough fiber, you may have trouble with regular bowel movements. So, over time, a high-protein and low-fiber dietary pattern can cause constipation.
Recommended daily intake of protein
Your protein needs vary based on your age, sex, and exercise level. Protein requirements may also depend on your health goals, like if you’re trying to lose weight or gain muscle.
In general, people on high-protein diets try to get at least 20% of calories from protein. That’s calculated at 1.2 g to 2 g of protein per kilogram of body weight per day.
As an example, a person who weighs 150 lbs (68 kg) would need between 82 g and 136 g of protein per day. That still leaves plenty of room for carbohydrates in the diet, such as fiber-rich vegetables, fruits, and whole grains. A high-protein diet doesn’t have to be low in fiber!
How to avoid constipation when eating a high-protein diet
Getting enough fiber is one important way to avoid constipation. But drinking enough fluids and getting enough physical activity are also key. This applies whether you’re on a high-protein diet or not.
Fiber intake
If you’re constipated, consider keeping a food diary for a few days so you can see how much fiber you’re getting. Chances are, your constipation is linked to low fiber intake.
The Dietary Guidelines for Americans recommend 22 g to 28 g of fiber for women and 28 g to 34 g of fiber for men each day. That amounts to roughly 4 to 5 servings of fiber-containing foods. Most people in the U.S. get only half the amount of the daily fiber they need.
Foods that are excellent sources of fiber include:
Vegetables, especially artichokes, peas, and squash
Fruit, especially avocado, guava, and raspberries
Legumes, such as chickpeas, black beans, and lentils
Seeds, such as chia, hemp, and flaxseed
Nuts, like almonds, pistachios, and hazelnuts
Whole grains, such as wheat, oats, and barley
If you can’t get enough fiber from food, you can also try fiber supplements, such as psyllium. It’s a good idea to talk with a healthcare professional before starting a fiber supplement. Especially if you have a medical condition that contributes to your constipation.
Fluid intake
Getting enough water and other fluids is crucial, since fluids make stools softer and easier to pass. Each person’s exact fluid needs vary, but the Institute of Medicine of the National Academies recommends:
125 oz of water (around 16 cups) daily for men
91 oz of water (around 11 cups) daily for women
Water isn’t the only option. Coffee, tea, certain juices, and probiotic drinks can also help ease constipation.
Physical activity
Experts recommend that adults should get at least 150 minutes per week of moderate-intensity activity, or 75 minutes of vigorous-intensity activity. But any type of physical movement routine is likely to help keep you regular.
Aerobic activity stimulates muscles in your intestines. This leads to faster transit times (the time it takes for ingested food to travel through the gut) and better bowel movements. Exercise also stimulates the vagus nerve and slows blood flow to the gastrointestinal (GI) tract, which increases the release of hormones that help you poop.
Frequently asked questions
There are two types of fiber, and each plays a role in helping you poop:
Soluble fiber dissolves in water, and makes stool softer and easier to pass.
Insoluble fiber doesn’t dissolve in water. It helps increase the weight and size of your poop (bulkier stool is often easier to pass).
In addition, fiber:
Helps the muscles of the gut push food through the digestive process
Supports the gut microbiome by maintaining a healthy balance of bacteria in the digestive tract
Prunes are a natural laxative. They contain fiber and a nondigestible sugar alcohol called sorbitol. Together, these ingredients help form soft, bulky stools. In fact, prunes may work even more effectively than psyllium fiber to help ease constipation.
Other foods that may help ease constipation quickly include:
Kiwi
Chia seeds
Cherries
Olive or flaxseed oil (or flaxseeds)
There aren’t specific foods that directly cause constipation. Your dietary pattern over time has the biggest effect on your bowel habits.
But if you’re constipated, it’s best to avoid foods that are high in fat, high in sodium, and low in fiber, such as:
Dairy
Fried foods
Fast foods
Red and processed meat
Other processed foods
Note that eating too much fiber can also trigger constipation. Especially if your body is not used to it. Most adults don’t get enough fiber. But, if you’re getting too much, try cutting back to see if symptoms improve.
It’s not recommended to eat more than 2 g of protein per kilogram of body weight per day. At this high intake, excess protein may be linked to kidney problems. And diets with a very high intake of protein from red and processed meat are linked to an increased risk of colorectal cancer.
The bottom line
Protein doesn’t directly cause constipation. But high-protein diets are often low in the fiber-rich carbohydrates that help ensure regular bowel movements. Without enough of them in your diet, you may experience constipation. So, if you eat a high-protein diet, it’s important to make sure you’re getting enough fiber. Excellent sources include whole grains, fruits, vegetables, and legumes. Getting enough fluids and exercise will also help prevent constipation.
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References
American College of Sports Medicine, et al. (2016). Nutrition and athletic performance. Medicine & Science in Sports & Exercise.
Attaluri, A., et al. (2011). Randomised clinical trial: Dried plums (prunes) vs. psyllium for constipation. Alimentary Pharmacology and Therapeutics.
Centers for Disease Control and Prevention. (2024). Fiber: The carb that helps you manage diabetes.
Diaz, S., et al. (2023). Constipation. StatPearls.
Ko, G., et al. (2020). The effects of high-protein diets on kidney health and longevity. Journal of the American Society of Nephrology.
National Institute of Diabetes and Digestive and Kidney Diseases. (2018). Eating, diet, & nutrition for constipation.
Reynolds, S. (2021). Pattern of DNA damage links colorectal cancer and diet high in red meat. National Cancer Institute.
Tantawy, S. A., et al. (2017). Effects of a proposed physical activity and diet control to manage constipation in middle-aged obese women. Diabetes, Metabolic Syndrome and Obesity.
U.S. Department of Agriculture. (2020). Dietary Guidelines for Americans 2020-2025.
U.S. Department of Health and Human Services. (2018). Physical activity guidelines for Americans.
