In small amounts, watermelon isn’t particularly likely to cause gas.
However, it’s incredibly easy to eat a ton of watermelon in a single serving, which can lead to excessive gas and bloating.
I’ll explain why this occurs, and then we’ll look at how much watermelon causes gas problems for most people.
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Why Fruit Like Watermelon Causes Bloating and Gas
Most carbohydrates break down and are absorbed in the stomach or small intestine.
However, some are hard to digest and end up being passed to the large intestine.
The bacteria in your large intestine then ferment these carbohydrates to extract some nutrients. But this fermentation process produces gas as a byproduct.
If that gas builds up, it causes bloating. In order for it to be excreted, most of it is passed out through flatulence.
That’s literally all most people will ever need to know to understand why farting occurs.
With that out of the way, let’s look at the hard to digest carbohydrates in watermelon.
Fiber in Watermelon
The nutrition data below comes right from the USDA’s food database per 100 grams of watermelon.
This is equivalent to about 10 watermelon balls, or 1-2 large triangle slices.
| Watermelon | |
|---|---|
| Energy (kcal) | 30 |
| Protein (g) | 0.61 |
| Total Lipid (g) | 0.15 |
| Carbohydrate (g) | 7.55 |
| Fiber (g) | 0.4 |
| Sugars (g) | 6.2 |
As you can see, watermelon is low in fiber and basically all sugar.
From personal experience, I know that it’s possible to eat several servings of this size at one time without much difficulty.
This can lead to some complications.
Hard to Digest Carbohydrates in Watermelon
We saw that fiber might play a small role in gas in watermelon, but a minor one at most.
Luckily, there’s some research that measured carbohydrates that are difficult to digest for several foods, including watermelon.
I’ve reproduced the data for watermelon below:
| Watermelon | |
|---|---|
| Moisture | 90 g |
| Fructose | 2.37 g |
| Glucose | 2.49 g |
| Sucrose | 1.68 g |
| Mannitol | 0.12 g |
| Total FOS | 0.81 g |
There are a few things to understand here:
- Sucrose is exactly half fructose and glucose, so there’s a bit over 3 grams of fructose per 100 gram serving.
- Mannitol can cause stomach issues for some, but this is such a small amount that it’s unlikely to be an issue.
- Glucose is very easy to absorb.
FOS stands for fructooligosaccharides, which are difficult for most people to digest.
In addition, many people struggle to digest large amounts of fructose.
One study found that almost all healthy people can absorb 100% of 15 grams of fructose, but that number drops as the amount of fructose goes up:
- 90% of people could absorb 25g of fructose
- 20-30% of people could absorb 50g of fructose
When it’s not absorbed, it ends up fermenting in the gut and producing gas.
How Much Watermelon Results In Gas?
Let’s put everything together.
There are 3 main types of carbohydrates that can result in gas production:
- Fructose – About 3 grams per serving
- Fiber – 0.4 grams per serving
- FOS – 0.8 grams per serving
In a single “normal” serving, this isn’t enough to gas significant gas for most people.
However, if you eat something like half a watermelon, that’s close to 10 servings depending on the size of the watermelon.
At that point, there’s 30 grams of fructose, 4 grams of fiber, and 8 grams of FOS. The fiber likely isn’t a big deal, but the FOS and fructose certainly can be.
Many people can still digest that amount okay with no significant issues, but there’s a sizable part of the population that can’t. And if you eat anything else at the same time (or shortly before or after), that can add to gas problems.
