What Can Cause Intermittent Fasting Constipation and Other Bowel Problems in Some People

    intermittent fasting constipation

    Martin Alvarez

    Martin Alvarez
    Nutritionist/Dietitian Professional Guide

    Updated on 12/3/2022

    The explanation is not as complicated as you may believe.

    Your body and your health can go through many changes due to intermittent fasting (IF), including weight loss and improved sleep quality. However, nobody warns you about problems with your bowel movements, such as constipation. Yes, some people for whom intermittent fasting can completely disrupt their regular bowel movement patterns.

    Intermittent fasting has only one possible side effect, namely intermittent fasting constipation, but there are several others. Others have stated that they have the opposite problem, such as diarrhea, in certain instances where they have used the product.

    But if you have bowel movement issues, don't worry about it. According to Cynthia Quainoo, MD, a gastroenterologist at Gastroenterology Associates of Brooklyn

    A person's bowel movements and the consistency of their stools are directly related to what they eat or do not eat during the day

    Continue reading to find out why intermittent fasting causes changes to your bowel movement, as well as Dr. Quainoo's recommendations for ensuring that everything stays in the right direction.

    This is a plausible explanation. According to Dr. Quainoo, if a new medication does not cause diarrhea, you should investigate the possibility of another underlying condition, such as irritable bowel syndrome, celiac disease, an infection of the colon, a thyroid disorder, or celiac disease.

    Why Does Intermittent Fasting Make Some People More Prone To Constipation Than Others?

    intermittent fasting cause constipation


    According to Dr. Quainoo,

    Changes in diet can very easily cause changes in bowel movements.

    People who practice intermittent fasting may experience constipation as a side effect due to the lack of water and fiber in their diets, which can lead to the condition.


    Consider The Following:

     suppose you are eating less now that your window eating is limited. In that case, there is a possibility that you are not getting enough of the nutrients you need to keep your bowel movements regular, particularly dietary fiber. Dietary fiber is beneficial to the health of your digestive system because it increases the volume of stool and facilitates the movement of food through the digestive tract, two of the digestive system's most essential functions. Therefore, not getting enough of it can most definitely result in a decreased number of times the toilet is flushed.



    The same is true if you do not consume sufficient water and other fluids. Because fiber is only helpful if you consume an adequate amount of liquids, dehydration can make it even more difficult for your stool to pass, especially considering that adequate hydration is necessary for fiber to be effective.

    There is a good chance that you are consuming much less water if you participate in more extreme intermittent fasting, such as the OMAD diet. The less water you drink, the greater the likelihood that you will experience constipation. 

    It is true that the longer the fasting period, the less water you will take in.
    Says Dr. Quainoo, adding that you must remember that foods also have water in them.
    If you fast for a longer period, you will consume less water as a result.



    According to Dr. Quainoo, "constipation" refers to a condition in which a person has fewer than three bowel movements in a week or goes three days or more without a bowel movement. Dr. Quainoo emphasizes that one can have regular bowel movements despite suffering from constipation. 

    It is also important to consider the consistency of the stools; stools that are hard, large, dry, and require a lot of effort to pass can also be considered constipation.


    What Should You Do If, Instead Of Constipation, You Have Diarrhea?

    You Have Diarrhea


    Even though you might think that the change in your diet is to blame for looser stools, there is a possibility that this may not be the case. There is no doubt that diarrhea is not typically brought about by fasting on its own. There are several different causes of diarrhea, but generally speaking, there are a few common ones. She claims that lactose intolerance and the side effects of certain medications are the most prevalent and least harmful causes.

    Therefore, one possible explanation is that you've recently added something new to your diet, such as a dairy product, to which you previously had no idea that you had an intolerance. This is a plausible explanation. According to Dr. Quainoo, if a new medication does not cause diarrhea, you should investigate the possibility of another underlying condition, such as irritable bowel syndrome, celiac disease, an infection of the colon, a thyroid disorder, or celiac disease.

    Talk to a medical professional if you're worried about having diarrhea that doesn't seem to get better.

    While on a Fasting Diet, What are Some Strategies For Maintaining Regular Bowel Movements?

    What are Some Strategies For Maintaining Regular

    Constipation with intermittent fasting can be overcome by eating more fiber and drinking more water during the non-fasting period, Constipation with prolonged fasting cannot be overcome.
    Dr. Quainoo explains straightforwardly.

    Specific Recommendations are as Follows:

    • Increase the amount of fiber you eat. According to Dr. Quainoo, the recommended fiber intake for active people is between 25 and 30 grams per day. Consuming an adequate amount of fiber will ensure that your stool is sufficiently bulky to pass and does so without difficulty. There are a great many foods that are high in fiber that you can incorporate into your diet, and some examples include sweet potatoes and Brussels sprouts.

    Drink enough water


    • Drink enough water. According to Dr. Quainoo, daily water should be between three and four liters. Combining fiber and water is the most effective way to encourage bowel movement.

    Consume some coffee


    • Consume some coffee. A recent study has found that drinking coffee is associated with an increased frequency of the need to go to the restroom within four minutes of the beverage being consumed. According to Dr. Quainoo,
    Whether you choose to believe it or not, its mechanism of action is not completely understood.
    What we know is that drinking coffee causes the receptors in the colon to contract; however, it is thought that caffeine is not the primary offender in this scenario." Enjoy that cup of coffee in the morning (even if it's decaf and calorie-free so you can stay in compliance with the fasting window).

    get active


    • Get active. According to Dr. Quainoo, who explains that a sedentary lifestyle can be a contributing factor to constipation
    Physical activity stimulates bowel motility. Physical activity stimulates bowel motility. Increased bowel motility decreases the amount of time stool is in the colon. This decreases the amount of time stool is in the colon, which decreases the amount of water absorbed from the stool.
    She explains, This means the stool is less dry and hard, making it much easier to pass. She goes on to say that any form of exercise will stimulate bowel motility; however, she believes that aerobic exercise will be the most effective for intermittent fasting constipation because it will increase blood flow to all organs, including the gastrointestinal tract.