Why Does the Keto Diet Cause Constipation—And How Can You Stop It?

A person sitting on the toilet with constipation

Westend61 / Getty Images

Following the keto diet can be very strict and difficult to maintain, and often comes with a complaint: constipation. If you’re following the keto diet and your bowel movements become infrequent, it's not a huge surprise. After all, the diet is void of fiber-rich foods that help keep you regular. Thankfully, there are ways to follow the keto diet without the dreaded backup.

The ketogenic diet is commonly referred to as 'keto.’ In the 1920s, it was used as a treatment for children with epilepsy, but these days it’s known for its weight-loss effect. The keto diet market continues to grow in size annually—in fact, 6% of people in the United States follow the keto diet every year.

Keto involves drastically cutting back on carbs and increasing your fat and protein intake. If followed to a tee, your body will enter a state of ketosis, burning fat as its main source of energy, rather than the sugars from carbs. This is achieved by dividing your macronutrient consumption into around 55-60% fat, 30-35% protein, and 5-10% carbs.

What Causes Keto Constipation?

Foods with tons of soluble and insoluble fiber (think: vegetables, fruit, grains, and starches) are key for regular bowel movements. But the keto diet is largely void of food with fiber, making you more prone to be constipated.

Most people in the U.S. do not get enough fiber in their diets already, so how might the problem be worse for followers of keto?

Low-Fiber Diet

Keto is lean on carbs—under 50 grams a day (about 1.8 ounces) to be precise. Instead, it consists mainly of fats and protein. Therefore, you run the risk of under-consuming fiber-rich foods.

Consuming fiber is important. Soluble fiber works by absorbing water and encouraging the movement of food through your digestive tract. Insoluble fiber, on the other hand, acts as a bulking agent. Reducing your fiber intake may also alter your intestinal microbiota, which is partly responsible for the breakdown of food. This lack of fiber means up to 50% of people following a keto diet will experience constipation at some point.

An Increase in Dairy

Dairy lovers may enjoy keto for its inclusion of cheeses, yogurts, and creams, which are hefty fats and protein sources. But due to its lactose (the type of sugar in milk) content, dairy is a common culprit of constipation. Lactose can be hard to digest for many people and can lead to bloating, gas, nausea, and constipation.

A 2020 study evaluating the effects of high-versus-low dairy consumption on gut microbiome found that people following a high dairy diet experienced a reduction in specific butyrate bacteria, a bacteria that’s produced when you break down and digest fiber, which helps keep you regular.

Additionally, an imbalanced diet that relies heavily on dairy products and a lack of fiber-rich foods may also leave you feeling sluggish.

Reduced Water Intake

Drinking plenty of water is important for all bodily functions, including staying regular. But with reduced consumption of fruits and vegetables, your water intake may decrease without you realizing it.

A sudden drop in your carb intake makes dehydration and an imbalance of electrolytes all the more prevalent on a keto diet. That’s because each gram of glycogen (the stored form of sugar that’s your body’s main source of energy and is found primarily in carbs) is stored alongside 3 grams (0.1 ounces) of water within your muscles. 

To counteract this, make sure to guzzle sufficient water throughout the day and periodically glance at the color of your urine as a marker of hydration.

How to Treat It

Following a keto diet is extremely strict and can be very difficult to maintain. To stick with a keto diet and sidestep constipation, try the following:

Add More Dietary Fiber

According to the Academy of Nutrition and Diuretics, women should aim for around 25 grams (0.9 ounces) of fiber daily, and men should aim for 38 grams (1.2 ounces) of fiber daily. Luckily, there are a variety of keto-friendly, fibrous foods:

  • Sliced avocado: 6.7 grams (0.2 ounces) of fiber per 100 grams (3.5 ounces) serving
  • A sprinkle of chopped almonds: 3.5 grams (0.1 ounces) of fiber per 28.35 grams (1 ounce) serving 
  • A cup of cauliflower: 2.2 grams (0.08 ounces) of fiber per 64 grams (2.2 ounces) serving

Exercise

Research has found that being active can help keep you regular. Aerobic exercise in particular can improve constipation by encouraging your intestines to contract. A brisk daily walk, light jog, or high-intensity fitness class may help regulate your bowel movements.

Retrain Your Bowel

Reestablishing frequent bowel movements can eradicate bouts of constipation and improve stool consistency. Retraining your bowel may be as simple as drinking sufficient fluids and establishing a regular time for a toilet break. Stimulation, such as a fiber supplement or a suppository, may also be required. Before turning to over-the-counter (OTC) medications, speak with your healthcare provider to learn if these products are right for you.

Increase Your Water Intake

Sufficient hydration is essential to rid your body of waste. Your recommended water intake will vary based on your sex, height, weight, and if you are pregnant or breastfeeding. But as a rule of thumb, drink before thirst sets in and use the color of your urine as an indication of hydration. The darker it is, the more dehydrated you are. 

Cut Back on Dairy

If you suspect dairy is causing your constipation, experiment with reducing or eradicating your intake. 

How to Prevent Keto Constipation

If you're new to the keto diet, consider easing in by slowly introducing more fats and protein-rich foods, while cutting back on the carbs. Many high-fiber and low-carb foods are permitted on keto—such as artichokes and blueberries—helping regulate your trips to the bathroom. Or, give keto cycling a try to give your stomach time to adjust its digestion.

When to See a Healthcare Provider

It’s recommended you speak to a healthcare provider before you try a new diet like keto. And if you’ve already started, make sure to speak with your healthcare provider if you’re experiencing constipation. Ongoing stomach pain, bloating, gas, and even an anal fissure (a small tear in the lining of the anus) from excessive pushing are common complaints of constipation. 

Chronic constipation can also impact your mental health. A 2020 study involving 240 patients with constipation-predominant irritable bowel syndrome (IBS) found almost a third showed symptoms of depression, more prevalent among women.

Additionally, the keto diet could cause low blood pressure, kidney stones, constipation, nutrient deficiencies, and an increased risk of heart disease. Following strict diets like keto could also cause social isolation or disordered eating. Keto is not safe for those with any conditions involving their pancreas, liver, thyroid, or gallbladder.

A Quick Review

Keto is a fad diet known for its potential weight loss effects. The main idea is that by drastically reducing your carb intake, and increasing your consumption of fats and protein, your body enters a state of ketosis, where it burns fat as the main source of fuel, rather than glycogen. However,  while keto may help you lose weight,  it can also reduce the frequency of your bathroom visits, largely due to a lack of dietary fiber. 

Ultimately, following a keto diet can be very strict and difficult to maintain. And research on the diet’s effectiveness in treating obesity or diabetes is limited.

Was this page helpful?
Sources
Health.com uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Grand View Research. Ketogenic diet market size.

  2. International Food Information Council. 2021 food and health survey.

  3. Masood W, Annamaraju P, Uppaluri KR. Ketogenic diet. In: StatPearls. StatPearls Publishing; 2022.

  4. Rollet M, Bohn T, Vahid F. Association between dietary factors and constipation in adults living in Luxembourg and taking part in the oriscav-lux 2 survey. Nutrients. 2021;14(1):122. doi:10.3390/nu14010122

  5. American Society for Nutrition. Most Americans are not getting enough fiber in our diets.

  6. Zhao Y, Yu YB. Intestinal microbiota and chronic constipation. Springerplus. 2016;5(1):1130. doi:10.1186/s40064-016-2821-1

  7. Tuck CJ, Staudacher HM. The keto diet and the gut: Cause for concern? The Lancet Gastroenterology & Hepatology. 2019;4(12):908-909. doi:10.1016/S2468-1253(19)30353-X

  8. Leszkowicz J, Plata-Nazar K, Szlagatys-Sidorkiewicz A. Can lactose intolerance be a cause of constipation? A narrative review. Nutrients. 2022;14(9):1785. doi:10.3390/nu14091785

  9. Swarte JC, Eelderink C, Douwes RM, et al. Effect of high versus low dairy consumption on the gut microbiome: Results of a randomized, cross-over study. Nutrients. 2020;12(7):2129. doi:10.3390/nu12072129

  10. Boilesen SN, Tahan S, Dias FC, Melli LCFL, de Morais MB. Water and fluid intake in the prevention and treatment of functional constipation in children and adolescents: Is there evidence? Jornal de Pediatria. 2017;93(4):320-327. doi:10.1016/j.jped.2017.01.005

  11. Fernández-Elías VE, Ortega JF, Nelson RK, Mora-Rodriguez R. Relationship between muscle water and glycogen recovery after prolonged exercise in the heat in humans. European Journal of Applied Physiology. 2015;9(115):1919-1926. doi:10.1007/s00421-015-3175-z

  12. Academy of Nutrition and Dietetics. Easy ways to boost fiber in your daily diet.

  13. U.S. Department of Agriculture (USDA). Food data central search results.

  14. Gao R, Tao Y, Zhou C, et al. Exercise therapy in patients with constipation: A systematic review and meta-analysis of randomized controlled trials. Scandinavian Journal of Gastroenterology. 2019;54(2):169-177. doi:10.1080/00365521.2019.1568544

  15. About Constipation. Bowel retraining: Strategies for establishing bowel control.

  16. Centers for Disease Control and Prevention. Water and healthier drinks.

  17. Mokhtar NM, Bahrudin MF, Abd Ghani N, Abdul Rani R, Raja Ali RA. Prevalence of subthreshold depression among constipation-predominant irritable bowel syndrome patients. Front Psychol. 2020;0. doi:10.3389/fpsyg.2020.01936

  18. Drabińska N, Wiczkowski W, Piskuła MK. Recent advances in the application of a ketogenic diet for obesity management. Trends in Food Science & Technology. 2021;110:28-38. doi:10.1016/j.tifs.2021.01.080

Related Articles