Does Diarrhoea Make You Lose Weight? The Unpleasant Myths Explored

02 December, 2025  |  Holy Winter - Healthcare Writer

Does Diarrhoea Make You Lose Weight? Unpleasant Myths Explored

Learn whether diarrhoea causes weight loss, why it happens, and how to protect your health during digestive distress.

Diarrhoea is never pleasant - but some people wonder whether it can have the side effect of weight loss. While it might seem logical that losing fluids and frequent bowel movements could reduce body weight, the truth is more complicated. In this article, we’ll explore whether diarrhoea contributes to sustainable weight loss, what causes it, and why relying on it for weight loss is both unsafe and ineffective.

Can Diarrhoea Cause You to Lose Weight?

Yes - but not in the way you might think. When you have diarrhoea, your body loses water, electrolytes, and nutrients, not fat. The drop on the scales is usually caused by temporary dehydration, losing water weight, and not actual fat loss. Once you rehydrate and recover, your weight typically returns to normal.

In short:

• Short-term weight loss:Caused by dehydration.
• No fat loss:Your body’s fat stores remain unchanged.
• Temporary effect:Weight usually comes back once you rehydrate.

So, while diarrhoea can technically make you “lose weight,” it’s neither a sustainable nor healthy step on your weight loss journey.

Why Does Diarrhoea Happen?

Diarrhoea can be triggered by a range of factors and health conditions, including:

• Viral or bacterial infections(like food poisoning or stomach flu).
• Medications, particularly antibiotics.
• Food intolerances (like lactose intolerance for dairy products).
• Digestive disorders, including such as irritable bowel syndrome (IBS), ulcerative colitis, Celiac disease or inflammatory bowel diseases such as Crohn’s disease.
• Stress and anxiety,which can affect gut function.

In most cases, diarrhoea resolves on its own within a few days. Persistent, chronic diarrhoea, however, can lead to serious dehydration and nutrient deficiencies.

The Dangers of Diarrhoea-Induced Weight Loss

If you’re losing weight during an onset of diarrhoea, it’s a sign your body isn’t functioning properly. Chronic diarrhoea can lead to:

• Electrolyte imbalance.
• Dehydration(causing weakness, dizziness, and fatigue.
• Malnutrition(caused by poor nutrient absorption).
• Unintended weight loss which could signal an underlying condition.

If diarrhoea lasts more than a few days or is accompanied by symptoms like fever, blood in stool, or severe pain, seek medical help immediately.

Using Diarrhoea to Lose Weight: A Dangerous Myth

Some online “detox” trends falsely claim that diarrhoea or laxative use can help you lose weight quickly. This is extremely dangerous. These methods only remove water and waste - not fat - and can cause serious harm to your digestive system, kidneys, and heart.

Healthy, lasting weight loss should always involve:

• A balanced diet and weight loss plan - including plenty of fruit and vegetables.
• Regular exercise and increased overall physical activity.
• Medical guidance, especially if using treatments such as weight loss injections prescribed by professionals at iQ Doctor.

Safe Weight Management Options

If you’re struggling to manage your weight safely, speak to a healthcare professional. At iQ Doctor, our UK-certified clinicians provide access to trusted weight management treatments like Wegovy and Mounjaro, combined with expert guidance to help you achieve lasting results - without compromising your health.

Key Takeaway

Diarrhoea might cause a temporary drop in weight, but it’s not true fat loss - and it’s certainly not a healthy or sustainable method to use for any weight loss goals. Always treat diarrhoea as a symptom, not a weight loss solution. Stay hydrated, eat balanced meals, and seek medical advice if symptoms persist.

iQ Doctor is a registered UK pharmacy that specialises in medical remedies for weight loss (including Wegovy and Mounjaro), erectile dysfunction, hair loss support and much more. Whether you require over-the-counter relief, or prescription-only medication, the experts at iQ Doctor can assist. Please get in touch if you need any further advice.

Also, be sure to keep in touch with iQ Doctor via our social media channels as well as keeping up to date with us by signing up to the mailing list.