Watermelon has to be one of the most iconic fruits of the summer. A picnic in the park or a cookout at the beach isn’t complete without juicy watermelon slices at the table.

But if you’ve found yourself in the bathroom after eating lots of watermelon then you might be wondering if watermelon is good for your gut. Watermelon could make you poop and there might be some reasons why this is a possibility.

Why does watermelon make you poop?

  1. The most likely reason…sugar
  2. You might have a food sensitivity
  3. Maybe magnesium…

One thing to keep in mind, if you get the poops from this juicy summer fruit, what is really the deciding factor is how much watermelon you are eating vs the watermelon itself.

The most likely reason…sugar

Like all fruits, watermelon does have sugar that is naturally present. Note: Sugar that’s naturally found in fruits is not a bad thing. (I don’t want to scare people away from fruit).

When it comes to watermelon it is higher than other fruits with the amount of fruit sugar; so that combined with the amount you are eating is probably the most likely culprit.


This is the type of sugar that is found in high amounts in watermelon and is naturally present in many fruits. Let’s say you sit down and eat a huge bowl of watermelon, or another fruit high in fructose, you might notice looser poops or you’re pooping more.

Fructose is what we call a monosaccharide which is just a fancy way to say a single unit (mono) of sugar (saccharide). This type of sugar is usually going to be absorbed in your gut, especially the small intestine, but what can happen for some people is it doesn’t get absorbed. This means it can travel to the large intestine where it draws water into the gut leading to looser poops (2).

Watermelon and low fodmap

Fructose is part of a group of carbohydrates that fall under the acronym FODMAP. If you’re looking for a good intro to low FODMAP check out Kate Scarlata’s resources here about fodmaps 101. Essentially foods that follow under this category can be a trigger digestive issues.

Watermelon is considered a high fodmap food and it has a couple of different types of carbohydrates that can trigger digestive discomfort, like pooping. According to the Monash University FODMAP diet app, one-cup of watermelon is high in fructose, mannitol, and fructan (1).

You might have a food sensitivity.

You know how some foods just seem to bug you? It happens. It could be that you have a sensitivity to watermelon. The two biggest factors that impact food sensitivities are how much you eat and how often you eat it.

Maybe magnesium but…

It’s probably not at all related to magnesium.  You might have heard that magnesium can make you poop and a one-cup serving of watermelon will give you 15 mg of magensium (3).

Even if you were to sit down and eat half a watermelon, which is totally doable on a hot summer day, you wouldn’t be getting enough magnesium to make you poop. Plus, the form of magnesium matters more when it comes to making you go.

It’s when people are taking magnesium supplements, like milk of magnesia or magnesium oxide, that they will notice a laxative effect (4).

Moral of the story

Watermelon might make you poop and it’s probably because of the fructose or the other FODMAPs in it.

Does this mean you shouldn’t eat watermelon?

No. Especially because watermelon is pretty nutritious and hydrating.

If watermelon does make you poop then try limiting the portion size and/or how often you are eating it. That should help you a lot.

And I wouldn’t be @theguthealth.nutritionist if I didn’t talk about one final factor.

Can watermelon make your poop red?

It just might. Food pigments, whether they are natural or synthetic, can turn your poop different colors.

If you sit down and eat lots of watermelon or have it every day for a week you might notice a red or pinkish tinge to your poop. It’s a harmless side effect from this red fruit and will go away once you stop eating the watermelon.

Tell me in the comments, what’s your favorite way to have watermelon?