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Home arrow Nutrition arrow Intermittent Fasting arrow Intermittent Fasting Constipation: Why It Happens and How to Treat it

Intermittent Fasting Constipation: Why It Happens and How to Treat it

Written by Isabel Mayfield
Fact checked by Edna Skopljak, MD
Last update: October 15, 2023
4 min read 687 Views 0 Comments
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Constipation is a normal part of many people’s intermittent fasting journey, and that doesn’t mean it isn’t right for you.

intermittent fasting constipation

If you’ve noticed a difference in your bowel movements while practicing intermittent fasting, in that they don’t really happen, you may be concerned.

But constipation generally means that you’ve changed something in your routine, and if you’ve recently changed your eating habits, your body will likely need time to adjust. 

That being said, if you’re ready to make constipation a part of your past, the following information should help.

Why Does Intermittent Fasting Cause Constipation?

Intermittent fasting has many benefits, including improving the gut microbiome, reducing inflammation in the gut, and aiding in weight loss. 

And while these benefits can often lead to improved digestion, it’s common for fasters to experience some less-than-pleasant side effects – constipation being one of them.

Below, we’ll get into some of the most common causes of intermittent fasting-related constipation, followed by remedies that you can use to get moving again.

#1 Lack of fiber

High-fiber foods include things like fruits and vegetables, beans, and whole grains, and are essential for helping your intestines gather your stool and move it through the gastrointestinal tract. 

Although the fasting regime does not technically involve any eating restrictions that would limit dietary fiber intake, there are certain instances when people following an intermittent fasting diet may not consume enough fiber-rich foods.

Naturally, reducing the number of hours you eat per day by spending anywhere from 12 to 40 hours not eating can impact the amount of fiber you consume, making it hard to hit your daily recommendation.

#2 Reduced water intake

Water is involved in many essential processes related to digestion, including helping the gut break down food and keeping stool soft to support regular bowel movements.

Since up to 20% of your fluid intake per day comes from the foods you eat – with fruits and vegetables being especially great sources of water – limiting your eating window each day can affect your ability to stay hydrated.

It’s also easy to mistake the feeling of thirst for hunger and ignore your body’s cues to increase your water intake.

#3 Stress

Changing eating habits to adopt an intermittent fasting lifestyle can be stressful for the body. 

This stress has been shown to trigger the sympathetic nervous system, activating the “fight or flight” response which causes non-essential functions, like digestion, to slow or even stop. 

How to Treat Intermittent Fasting Constipation

Following an intermittent fasting lifestyle doesn’t have to mean fewer bowel movements. In this next section, you’ll learn simple fixes for constipation caused by intermittent fasting.

#1 Eat enough fiber

It’s estimated that most Americans eat only 15 grams of fiber per day, which is close to half of the 25–30 gram daily recommendation.

If you’re dealing with constipation, upping your fiber intake – either by eating foods high in fiber or taking an all-natural fiber supplement – is a good first step in supporting regular bowel movements.

#2 Stay hydrated

Drinking plain water or herbal tea during your fasting period is another simple fix for preventing bloating and constipation.

Increasing the amount of fruits and vegetables you consume during your eating window can also help ensure that you get all the necessary fluids per day.

#3 Get in some exercise

Regular exercise is an important part of any healthy lifestyle and has surprising benefits related to preventing constipation.

Aerobic exercises, such as walking, jogging, or cycling, can improve blood flow to the digestive system and stimulate the muscles that help move stool through the digestive tract.

#4 Drink coffee

Coffee causes the muscles of the intestine to contract in much the same way as exercise and, therefore, offers a similar effect.

It also has the added benefit of being a mild diuretic, meaning it increases urine production and fluid secretion, helping to prevent the effects of dehydration on your bowel movements. 

#5 Avoid processed foods

Processed foods are generally low in dietary fiber and water content, making them a bad addition to the diet of anyone who practices intermittent fasting.

They’re also full of preservatives and emulsifiers, which are shown to negatively affect digestive health.

A Word From a Nutritionist

An intermittent fasting lifestyle has many attractive benefits, such as effectively lowering cholesterol and blood pressure, reducing inflammation, and enhancing weight loss.

But regardless of its perks, adjusting your food intake and adopting a new style of eating isn’t always easy.

If you find yourself struggling with negative side effects, such as constipation or intense hunger and cravings, just remember that they’re not only normal but also preventable.

With time, practice, and the implementation of holistic lifestyle changes such as consuming a high-fiber diet, upping your water intake, and avoiding processed foods, you can enjoy all of the benefits of intermittent fasting without sacrificing regular poops.


How to prevent intermittent fasting constipation?

The easiest ways for you to prevent constipation while intermittent fasting is by increasing your water intake and fiber intake – either through supplementation or eating whole grains, and by incorporating movement into your daily routine.

How does intermittent fasting affect your gut?

Intermittent fasting has a few benefits related to gut health, including improving its microbiome, reducing inflammation, and even speeding up food metabolization, though the latter may require an adjustment period of a few days or weeks.

Should you fast when constipated?

If you’re constipated as a result of adjusting to intermittent fasting, it’s not a bad idea to return to your regular eating patterns. When you do, make sure to drink plenty of water, up the amount of whole grains in your diet, get regular exercise, and try fiber supplements if the problem persists.


The effects of constipation, such as bloating or fewer bowel movements than you’re used to, are normal parts of intermittent fasting and not a cause for alarm.

Whether or not you decide to take a break from this eating style to allow your body to adjust is up to you. 

But it’s important to remember that simple lifestyle changes, such as drinking more water, adding regular exercise into your routine, and generally giving your body time to adapt to a new eating habit, can make all the difference in making intermittent fasting a comfortable piece of everyday life.

Written by Isabel Mayfield
Isabel Mayfield is a certified yoga instructor with over 10 years of experience in the fitness industry. She is passionate about self-improvement and loves to help people improve their sense of self-worth through education and support in meeting their fitness goals.
The article was fact checked by Edna Skopljak, MD
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Written by Isabel Mayfield
Fact checked by Edna Skopljak, MD
Last update: October 15, 2023
4 min read 687 Views 0 Comments

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