Following a high protein diet without enough fiber may lead to constipation. Increasing fiber intake, drinking plenty of fluids, and regular exercise, may help prevent or relieve constipation.
Protein can also increase feelings of fullness, which may lead to people eating less of other food groups, such as sources of fiber.
This article discusses the possible link between protein and constipation and how to increase fiber intake to help prevent constipation.
Protein itself does not directly cause constipation. However, some high protein foods may be low in fiber. Not getting enough fiber can lead to constipation.
Foods high in protein and low in fiber
- processed foods, such as hot dogs
- fast food and prepared foods, such as snack foods
However, eating a lot of protein may mean people do not get enough nutrients from other food groups, such as fiber, which helps support regular bowel movements.
Eating more fiber may help prevent constipation. The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) recommends adults have a daily fiber intake of
A person can increase fiber in their diet by eating foods such as:
- vegetables, including broccoli, green peas, and carrots
- fruits, including apples, pears, berries, and oranges
- whole grains, including whole wheat breads and pasta, oatmeal, and bran
- legumes, including lentils, kidney beans, chickpeas, and black beans
- nuts, including almonds, pecans, and peanuts
It is also important to drink plenty of water and other fluids while eating a high fiber diet, which helps the fiber work properly.
Increasing fiber gradually can help the body adjust from a low fiber diet to a high fiber diet.
People may want to plan out high fiber meals to help prevent constipation.
A person can increase fiber within a meal by adding additional sources of fiber, such as:
- blending fruit, such as berries, into a smoothie for breakfast or adding fruit onto cereal or oatmeal
- adding vegetables and salad into a wholegrain sandwich
- adding oats to bread or baked goods
- adding beans into a vegetable soup or salad
- chopping up vegetables to stir into wholegrain pasta or noodles
Here is a helpful list of high fiber recipes:
This section answers some common questions about protein and constipation.
Does protein affect bowel movements?
According to a 2016 review, long-term high protein intake of more than 2 kilograms (kg) of protein per kg of body weight may lead to digestive issues. Increased protein intake may lead to diarrhea, abdominal discomfort, and nausea.
If people have a protein intolerance, it may cause gastrointestinal symptoms
How can I avoid constipation with protein?
A person may be able to avoid constipation with protein by:
- eating a diet high in fiber, aiming for at least 25 g of fiber a day for females and 38 g per day for males
- drinking at least 8–10 cups of fluid each day
- getting regular physical activity each day at a moderate-vigorous intensity, such as brisk walking
Can pea protein cause constipation?
A small-scale 2022 study examined how easily the body can digest pea protein in 15 participants.
Researchers found that certain amino acids in pea protein are less easy to digest than those in casein, a protein occurring in dairy. However, there were no significant differences in how the small intestine could digest either protein.
Overall, this small study concluded that pea protein is easy to digest, suggesting it may not cause digestive issues such as constipation.
Eating a high protein diet may lead to constipation if people lack fiber. Some sources of animal protein may be low in fiber.
A person can increase their fiber intake by adding good sources of fiber to each meal, such as vegetables, fruits, legumes, and whole grains.
Drinking plenty of water and getting regular exercise may also help prevent or relieve constipation.