Laxatives for weight loss: why they're not safe

The use of laxatives for weight loss is one of those diet fads that never seem to go away. 

Despite its enduring popularity, don’t believe the hype. The truth is that laxatives won’t help you lose weight in the long term. There are safer, proven options for weight loss that can actually work. Read on as we break down how laxatives work, the risks of using them for weight loss, and what you can do instead.

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No, laxatives will not help you lose weight in the long term. The idea that laxatives can help you lose weight is a myth that has persisted in popular culture due to a misunderstanding of how laxatives work. 

Because laxatives help you have a bowel movement, some people think they speed up how quickly food moves through the body. The myth is this idea that when food moves quickly through the digestive system, the body doesn’t have a chance to absorb as many calories before it gets passed through the GI tract, thus leading to weight loss. 

But that’s not how laxatives work. Laxatives usually affect the stools and the large intestine, not your stomach or small intestine, where food gets digested. Your body starts to absorb calories from food well before it reaches your large intestine, which is where the laxatives work their magic. By the time food reaches the large intestine, it’s mostly waste matter. Your body will continue absorbing some water and any remaining electrolytes on its way out, but the “weight loss” you might notice on the scale from taking laxatives is primarily water weight and stool. You’re not losing a meaningful amount of body fat. Once you drink water, the weight you just “lost” will return.

When used as directed and on an occasional basis, laxatives can reliably relieve constipation. However, you may experience some short-term side effects, such as diarrhea, nausea, bloating, vomiting, or stomach pain. Short-term, these are usually manageable, but using laxatives more often than recommended or for weight loss can lead to more serious problems.

Once food enters your large intestine, it absorbs the last remaining valuable bits of waste matter: namely, water and electrolytes. However, since laxatives speed up this process, laxative overuse can cause dehydration and electrolyte imbalances. If you’re not rehydrating or eating well, this can lead to symptoms like:

• Dizziness

• Fainting or lightheadedness

• Weakness

• Confusion

• Headaches

• Nausea

• Vomiting

• Heart palpitations

• Reduced urination or dark urine

Taking laxatives on a longer-term basis can also make it difficult to have a bowel movement without using them, so you may end up in a vicious cycle of chronic constipation where you become dependent on laxatives to poop. Laxative overuse can even create physical changes in the colon. Chronic use of stimulant laxatives may damage the nerves and muscles that help move stool through your intestines. Long-term laxative abuse can also create potassium deficiencies, kidney damage, and heart problems that can become dangerous if left untreated.  

Taking laxatives for weight loss is on the spectrum of disordered eating behaviors. In one study of teens and young adults, those who took laxatives for weight loss were almost three times more likely to develop an additional eating disorder within the next five years. Other studies have found that eating disorders may develop even sooner — within the next one to three years.

If you’re trying to lose weight, laxatives aren’t the answer. They don’t reduce calorie absorption and can cause dehydration and other health problems.

Your healthcare provider can help you understand if weight loss is a good idea for you and recommend an appropriate treatment plan. In some cases, weight loss is recommended since higher body weight can increase your risk for certain health conditions, including diabetes and heart disease.

Regardless of whether you’re at a healthy weight or not, if you’re struggling with body image and self-worth, a mental health professional can help.

If your healthcare provider recommends losing weight, try these approaches to lose weight safely and sustainably:

• Exercise regularly. Regular physical activity can help with weight loss and weight maintenance. Aim for at least 150 minutes of moderate exercise per week, and try to adopt a mix of resistance training and aerobic-based workouts. 

• Improve your diet. Calories in vs. calories out play the largest role in weight loss (or gain). Eating more protein, fruits, vegetables, and fiber-rich foods can boost feelings of fullness and prevent overeating. Try to limit foods and drinks high in added sugar and empty calories, including soda, and alcohol.

• Weight loss medications can also help with weight loss when combined with diet and exercise. Ask your healthcare provider whether injectable medications like Wegovy (semaglutide) or Zepbound (tirzepatide) may be right for you. 

Ultimately, using laxatives for weight loss is not a good idea, and there are far better (safer and more effective) ways to lose weight.

• Laxatives are not a safe, effective, or long-lasting way to lose weight. The only weight you’ll lose is a short-term loss of water and stool.

• You should only use laxatives for their intended medical use.

• Laxatives can cause uncomfortable and potentially dangerous side effects when you use them on a long-term basis. 

• Talk to your healthcare provider about a weight loss plan that includes lifestyle changes such as diet and exercise. Ask your healthcare provider if medications like Wegovy (semaglutide) or Zepbound (tirzepatide) might be right for you.