Will a Juice Fast Give You Diarrhea?

Juice fast enthusiasts say diarrhea is normal and expected on a juice fast diet because juice is a natural laxative. Diarrhea, although uncomfortable for you, is a sign your body is ridding itself of all those toxic substances, they say. But that's not really what's going on, according to the American Cancer Society. A juice fast can cause diarrhea, but it's usually due to the high concentration of sugar in the juice. Consult your doctor before starting a juice fast.

In a juice fast, you eliminate all solid foods from your diet and drink only juice made from fresh fruits and vegetables. Also referred to as a cleanse or detox, a juice fast fills your cells with antioxidants and phytonutrients, while helping your body rid itself of harmful toxic substances, according to Juicing-for-health.com. You are also allowed to drink water on your fast, and some diets also permit tea and vegetable broth. The length of the diet varies, but generally it lasts for three or more days.

Too much juicing of fruit can cause severe diarrhea, according to the American Cancer Society. The high concentration of fructose, the sugar found in fruit, is the likely cause of your juice fast diarrhea. Foods high in sugar increase the rate at which stool leaves your large intestine, leading to watery bowel movements. The fruit juice may also cause osmotic diarrhea, which is when your colon cannot absorb all the sugar in the juice, increasing its water content. You may not experience diarrhea if your juices contain more vegetables, which are lower in sugar than fruit.

While proponents of juice fasts say diarrhea is normal and expected, if left uncontrolled, the diarrhea can lead to dehydration and electrolyte imbalance. The course of treatment for diarrhea is to avoid the food causing it, says the Merck Manual. If your juice fast is increasing your trips to the bathroom, you may need to stop the fast or drink more low-sugar vegetable juices.

Juice fasts are said to help rid your body of toxic substances, but there is no scientific evidence to support these claims, according to KidsHealth. A juice fast may lead to electrolyte imbalance, fatigue, nausea, hunger and headaches. These diets are also very low in calories and may be deficient in a number of essential nutrients, including calcium if you're not getting enough leafy greens; vitamin D; vitamin B-12; and omega-3 fatty acids. You should not follow a juice diet for any great length of time.