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Does a juice fast make you constipated?

Juice fasting has become an increasingly popular way to detox, lose weight quickly, and reset your digestive system. However, one of the most common concerns is that doing a juice fast will lead to constipation. In this article, we’ll take an in-depth look at whether juice fasts really do make you constipated.

What is Constipation?

Before we dive into whether juice fasts cause constipation, let’s clarify what constipation actually is. Constipation refers to infrequent, difficult, or incomplete bowel movements. Some common signs of constipation include:

  • Having fewer than 3 bowel movements per week
  • Passing hard, dry stool
  • Straining during bowel movements
  • Feeling like you can’t completely empty your bowels
  • Having abdominal pain or bloating

Occasional constipation is very common and usually not a major cause for concern. However, chronic constipation that persists for weeks or longer can be uncomfortable and even harmful to your health.

Why Juice Fasts May Lead to Constipation

There are a few reasons why doing a juice fast may make you constipated:

Lack of Fiber

Fiber is essential for healthy bowel function. It adds bulk to your stool and helps move waste through your digestive tract. Fresh fruits and vegetables naturally contain fiber, but a lot of it is removed when making juice. For example, an apple contains about 4 grams of fiber, but apple juice has none.

Without adequate fiber, stool can become dry and difficult to pass. The lack of fiber is one of the main reasons juice fasts could cause constipation.

Not Enough Fat

Dietary fat helps stimulate bowel movements by triggering the release of bile from your gallbladder into your intestines. Bile acts as a natural laxative. Since juices contain virtually no fat, doing a juice fast may deprive your body of a key compound for keeping your digestive system running smoothly.

Low Calorie Intake

Juice fasts typically only provide 600-1000 calories per day. This drastic calorie deficit can slow down your metabolism and digestive processes. Your colon needs less energy and therefore doesn’t contract as vigorously to move stool through.

Furthermore, very low calorie intake triggers your body to absorb a higher percentage of nutrients and water from your food. This can result in harder, drier stool that is more difficult to pass.

Not Chewing Food

Chewing begins the digestive process in your mouth by mixing food with saliva. This helps break down your food and make it easier for your body to digest and absorb nutrients. It also triggers nerves that support healthy bowel function.

Since you drink juice fasts rather than chew solid foods, your body misses out on this important pre-digestive phase. Going extended periods without chewing and eating whole foods can impair regularity.

Tips to Prevent Constipation on a Juice Fast

If you want to do a juice fast but are concerned about constipation, there are some things you can do to help maintain regular bowel movements:

Include Some Pulp

When making homemade juices, leave some of the pulp in rather than straining it out. The extra fiber from pulp can help counteract the lack of fiber when juicing produce.

Drink Prune Juice

Prune juice is well-known for its laxative effect. Drinking a small glass of prune juice once or twice a day can help stimulate bowel movements.

Add Healthy Fats

Consider blending avocado, nut butters, flaxseed oil, or coconut oil into your juices to add some healthy fats back into your diet.

Stay Hydrated

Drink plenty of water, herbal tea, and broth in addition to juices. Proper hydration is key for keeping your bowel movements regular.

Exercise Daily

Physical activity stimulates contractions in your colon that can help move stool. Aim for at least 30 minutes per day of moderate exercise like walking.

Take Probiotics

Probiotic supplements can support healthy gut bacteria and regularity. Look for broad spectrum probiotic formulas.

Use Flushing Supplements

Natural laxatives like magnesium or triphala can help flush out your digestive system. But use them sparingly and take breaks to avoid dependence.

Example Juice Fast Schedule to Prevent Constipation

Here is a sample 1-day juice fast schedule designed to minimize constipation:

Time Beverage
7 AM 16 oz lemon water
9 AM Green juice with spinach, kale, cucumber, celery, parsley, lemon, ginger, and apple
11 AM 8 oz coconut water
1 PM Carrot, beet, prune juice blend
3 PM Herbal tea with probiotic capsule
5 PM Orange, carrot, turmeric juice
7 PM Vegetable broth

This incorporates prune juice, broth, probiotics, and teas to support digestion. The vegetable-heavy green juices also provide fiber and nutrients.

When to See a Doctor

Occasional constipation during or after a juice fast is normal. However, if you experience severe or persistent constipation, it’s best to stop fasting and see your doctor.

See a doctor right away if you have:

  • No bowel movement for 3+ days
  • Hard, painful abdomen
  • Nausea and vomiting
  • Bleeding from the rectum
  • Weakness or fatigue

These can be signs of a serious issue like a bowel obstruction that requires medical treatment. Your doctor can help determine if an underlying condition is causing your constipation.

Long-Term Effects of Juice Fasts on Bowel Health

The impacts of juice fasting on constipation are typically short-term. Your bowel movements usually return to normal within a few days after ending a juice fast.

However, some people report improvements in their bowel function over the long run after doing periodic juice fasts. Possible explanations include:

  • Reset of digestive enzymes and bacteria
  • Removal of processed/inflammatory foods
  • Increased vegetable and nutrient intake
  • Improved hydration habits
  • Starting a healthier diet after the fast

That said, more research is still needed on the potential long-term gastrointestinal effects of juice fasts.

Other Juice Fast Side Effects

In addition to possible constipation, other potential short-term side effects of juice fasting include:

  • Hunger pangs
  • Headaches
  • Irritability
  • Fatigue
  • Reduced strength
  • Nausea
  • Dizziness

These typically resolve within a few days as your body adjusts. Drinking enough fluids, adding a small snack if needed, and gradually transitioning off the fast can help minimize adverse effects.


Constipation is a common concern for people considering a juice fast due to the lack of fiber. However, there are ways to modify your juice fast to help maintain regular bowel movements. Staying well hydrated, including some pulp, adding healthy fats, and taking probiotics can all help prevent constipation.

Occasional constipation during a short juice fast is usually not harmful. But chronic, severe constipation requires medical attention. Most people’s bowel habits return to normal within a few days of ending a juice cleanse. Some even report long-term improvements in digestion from periodic fasting.

Overall, pay attention to your body’s signals and adjust your juice fast as needed. Stop immediately if you experience severe side effects. With proper precautions, juice fasting can be safely implemented for most healthy adults in the short term.