The Truth About Laxatives For Weight Loss

Laxatives are medicines that stimulate bowel movement or soften stool to relieve constipation¹. They are perceived as easily accessible and harmless drugs, making them freely available for self-medication².

Different types of laxatives:

There are many kinds of laxatives, depending on your needs.

• Stimulants trigger bowel movement to help pass stool. 

• Lubricants lubricate the stool to soften it and make it easier to pass. 

• Stool softeners soften your stool to make it easier to pass. 

• Osmotics bring water to the colon to soften stool. 

• Bulking agents absorb liquid bulk up and soften the stool.

Why are laxatives becoming more popular?

Laxatives are increasingly becoming more popular as a way to lose weight as people mistakenly believe that taking laxatives will help pass more stool.

People also believe that laxatives aid in quickly moving undigested food through their digestive system to prevent the absorption of calories¹ and enhance weight loss.

There is a lot of debate as to whether taking laxatives is a safe and effective way of losing weight.

Can you lose weight with laxatives?

The simple answer is no.

When you ingest food, the small intestine mainly absorbs nutrients while the large intestine absorbs water and electrolytes, leaving what remains to form stool¹.

Most laxatives work to relieve constipation by increasing absorption of water in the colon to soften the stool, making it easier to pass¹.

While most people may experience “weight loss” after taking a laxative, this is a temporary process of the body losing water, not body fat³. This water loss can be almost always replenished when you drink something.

To date, there is no convincing evidence to show that laxatives help with long-term weight loss. One study showed that laxatives were ineffective for managing weight⁴.  Another study observed a “modest effect” on calorie absorption at high doses of stimulant laxatives³.

What are the potential risks of taking laxatives for weight loss?

Health professionals do not recommend taking laxatives for weight loss. The temporary weight loss observed after taking laxatives does not outweigh the numerous potential side effects of taking them.

Diarrhea

The primary and most common side effect of taking laxatives is diarrhea. This is due to the loss of a large volume of water when stool passes. Chronic diarrhea can result in rectal prolapse, where part of the intestine may stick out from the anus due to loss of the anal tone. 

Dehydration

Another significant side effect of taking laxatives is dehydration¹, as most laxatives draw water to your colon from different areas in your body. Some symptoms of dehydration include thirst, fatigue, dry skin, dizziness, or nausea. It’s crucial to replenish the fluid lost when taking laxatives to prevent a thirst trap.

Electrolyte imbalances

Chronic use of laxatives may cause disturbances in the body’s electrolyte balance. Electrolytes are substances in the bodily fluids that help with the daily functioning of your cells⁵. The main electrolyte in stool water is potassium, followed by sodium and chloride. The loss of liquid stool containing high potassium may lead to lower than normal levels of potassium in the blood, called hypokalemia¹ ⁶.

Several studies observed a significant risk of electrolyte imbalances, including hypokalemia, in patients who were given laxatives⁶ ⁷. Hypokalemia and other electrolyte imbalances can lead to downstream life-threatening health problems like renal, cardiac arrest, and metabolic disturbances¹.

Constipation

Long-term use of excess laxatives can also perpetuate constipation due to the body developing tolerance and dependence¹. This means that the body is used to responding to the laxatives, causing a decline in the body’s natural way of producing bowel movements. Consequently, this requires more laxatives to pass stool. This eventually leads to a vicious cycle of laxative misuse.

Severe adverse effects

In severe cases, misusing laxatives can lead to downstream life-threatening consequences like damage to numerous organ systems such as the heart, kidney, gut, and muscle¹ ⁹.

Drug contraindications

Lastly, there may be possible contraindications with the use of laxatives. 

Laxatives can interact with other drugs that you may be taking. You may also not react well due to pre-existing or underlying health conditions, especially gastrointestinal problems (e.g., irritable bowel syndrome).

Before taking laxatives, check with your doctor or pharmacist if it is safe to take them.

The lowdown

Laxatives may be an effective way to increase bowel movement and relieve the agitating symptoms of constipation. However, they will not help with long-lasting weight loss. Laxatives may cause temporary weight loss, but this is mainly water loss rather than fat, which can be immediately replenished after a drink.

Chronic laxative use for weight loss doesn’t have any long-term weight management effects. However, it introduces dangerous risks like diarrhea, dehydration, electrolyte imbalances, possible dependence, and misuse. If you have any questions about taking laxatives or how to lose weight safely, please talk to your doctor.