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Weight Loss

Do You Lose Weight When You Have Diarrhea

Do you lose weight when you have diarrhea? You might’ve read that diarrhea helps the body burn fat, but is it true? Or is this just another one of those internet rumors?

Diarrhea is a condition, which occurs when the stool becomes loose, watery, and more frequent than normal. Diarrhea can be due to different causes like food allergens, bacteria, viruses, parasites, and drugs. While in most cases, diarrhea is an uncomfortable temporary problem, it may be fatal in some cases.

Key Points

  • We all know that dieting is key to weight loss, but what happens when you have diarrhea on a diet?
  • Diarrhea may cause you to lose weight, even though it may be an inconvenience for this short term
  • Diarrhea is not a magical weight-loss cure-all

The Role of FODMAPS

Fodmaps are food additives that trigger symptoms in some people — gas, bloating, nausea, etc. — after ingesting certain foods.

The scientific term for them is “probiotics.” They help those bacteria in your gut, which occupy about 95 percent of your digestive tract, assimilate food and reproduce. Some fodmap foods, such as onions and garlic, have prebiotics, which feeds those probiotics.

Most fodmap sufferers are intolerant to fructans, a type of fiber found in some fruits and vegetables. Fructans can cause gas, and when that gas gets trapped in your digestive tract, it can cause bloating, cramping, and diarrhea.

Allowing to the National Institutes of Health, more than 20 million Americans are afflicted with IBS, the catch-all term for various gastrointestinal disorders.

The National Institutes of Health recommends that people with IBS consult a gastroenterologist to confirm the diagnosis, rule out more serious conditions, and prescribe an appropriate treatment plan.

In 2014, the mayoclinic published a study suggesting that fodmap-free diets can help relieve IBS symptoms in certain patients. After eliminating fodmap foods from their diet, researchers followed 39 patients for 14 weeks and found that 26 of them experienced significant relief from IBS symptoms, including abdominal pain, diarrhea, constipation, and bloating.

Although fodmap-free diets can be successful for many people with IBS, talking to your doctor before taking this drastic step is important.

How Is It Assumed Diarrhea Helps with Weight Loss?

The best way I can explain it is that the act of having diarrhea causes you to lose water weight. Think of it conceptually. When you drink a lot of water, you urinate out a lot of the water. When you poop, you poop out a lot of the water. So diarrhea causes you to lose a lot of water weight.

Now, not all diarrheas will cause this, but most will. You drink a lot of water and you only go to the bathroom once that day, you might lose 100 or 200 calories in a fluid. But if you drink a lot of water and go to the bathroom ten times a day, you’re peeing out at least 1,000 calories per 10-hour period — and that’s a lot of water weight.

Now, yes, diarrhea can cause you to lose a lot of fluid, and that fluid might not have any calories. So you might lose weight, but you could also lose minerals, vitamins, and other nutrients. But 1,000 calories of fluid loss is a lot, and you’ve likely lost about 10 percent of your body weight in fluid.

The other weird part is that diarrhea can help you lose fat. In short-term studies, people who had diarrhea lost more fat than people who didn’t. But eventually, your bowels get back to normal, and the fat comes back on.

The net result? You sometimes lose a lot of weight, but you sometimes gain it right back. It’s possible to yo-yo with diarrhea.

If you’re trying to lose weight, it can be an effective short-term tool. But a longer-term solution would be to change your eating habits.

Do You Lose Weight When You Have Diarrhea

Even though diarrhea is a fairly common condition, few people have questions like “Do I lose weight when I get sick with diarrhea?”

There are two main reasons that you might be wondering. The first is that you naturally lose water when you pass intestinal waste, so why shouldn’t you? The second reason is that diarrhea is often caused by eating large amounts of junk food or fried foods, so it makes sense that you might lose weight when this happens.

But does diarrhea cause weight loss?


Your body loses no weight at all. Your body is mostly made of water, and losing even a small amount of that water can cause dehydration.

Dehydration can also put you at risk for more serious conditions, including infections and even death. The good news is that diarrhea usually resolves itself after a couple of days.

So, how much water might you lose?

Most people lose between 1 to 2 pounds (0.5 to 1 kg) of body weight when they experience diarrhea.

That might not sound like much, but keep in mind that diarrhea can make you feel very tired and weak.

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