It’s one of the simplest joys of summer—watermelon. With its vibrant red flesh, ultra-refreshing texture, and promise of cool relief, it’s a seasonal favorite.

We love it sliced, cubed, or blended into smoothies. But behind its image as a “healthy” fruit lies a lesser-known effect on the body—particularly on blood sugar levels.

A Sneaky Spike in Blood Sugar?

Long praised as a weight-loss-friendly fruit thanks to its high water content and low calorie count, watermelon makes a comeback on every table once temperatures rise. But recent studies are raising eyebrows: this sweet and seemingly innocent fruit can cause a rapid spike in blood sugar—sometimes even sharper than that caused by white sugar.

Why? Because watermelon contains very little fiber and virtually no fat or protein—the very elements that usually help slow down sugar absorption. The result: once it hits your mouth, its natural sugars (glucose + fructose) are absorbed quickly, causing a sharp metabolic spike—especially in people over 50 or those with insulin sensitivity.

A Surprisingly High Glycemic Index

Watermelon’s glycemic index (GI) ranges from 72 to 80 depending on the variety, putting it firmly in the “high GI” category. For comparison, apples have a GI of 38, strawberries 41, and white sugar sits around 65.

What does that mean in practice? Eating a 150g serving of watermelon on an empty stomach can raise your blood sugar more than 50g of pure sugar would. And with a sharp spike comes a sudden crash—leaving you feeling tired, hungry, and craving more sugar. That’s the dreaded “sugar rollercoaster” we’d all rather avoid.

How to Enjoy It Without Spiking Your Blood Sugar

Watermelon isn’t your enemy. But like any food high in fast-acting sugars, it calls for a bit of strategy. Here’s how to enjoy it without upsetting your glucose balance:

• Avoid eating it on an empty stomach: This intensifies the blood sugar spike.
• Pair it with a source of protein or healthy fat: Try it with plain yogurt, a handful of almonds, or a spoonful of cottage cheese.
• Practice moderation: 100 to 150 grams (about 1 cup) is enough to refresh without overdoing it.
• Have it at the end of a meal, rather than as a stand-alone snack.
• Mix it up with lower-GI fruits: Think kiwi, apples, raspberries, or oranges to keep your fruit intake balanced.

The Takeaway

Watermelon doesn’t need to be off-limits—not at all! But it should be enjoyed mindfully, especially if you’re watching your blood sugar or often feel an energy dip after eating. Because yes, a fruit can be both hydrating and a little bit of a blood sugar rollercoaster.

Refreshing and delicious—but best savored smartly—watermelon is a true summer treat to enjoy in moderation, not in an all-you-can-eat buffet style.