Health Benefits of Watermelon: Nutrition, Calories, and Smart Eating Tips

Summer is officially here which means watermelon season has arrived. Markets and roadside stands are filling up with giant, juicy, red watermelons, often accompanied by a pinch of salt, a bit of Bulgarian cheese, or just a nostalgic smile for childhood memories. Beyond the sweet taste, it’s worth understanding what watermelon actually offers, and how much of it you should be eating.

Watermelon is made up of about 92% water, making it one of the most refreshing fruits around. It contains vitamin C, potassium, vitamin A, and lycopene- an antioxidant that research has linked to reduced inflammation and protection for the heart and skin. That said, while watermelon is low in fat, it’s not exactly low in sugar. Every 100 grams of watermelon has about 30 calories, most of which come from natural sugars.

How many calories are in a slice? That depends on the size, of course. An average slice (about a quarter-circle cut 2–3 cm thick) weighs between 300-400 grams, which means it can contain anywhere from 90 to 120 calories. Add a couple more slices, and you’re looking at a 300-calorie dessert.

As with anything, balance is key. A slice or two a day is a good rule of thumb, and watermelon makes a great alternative to cake or ice cream for dessert. Those with diabetes or prediabetes should be especially cautious, as it can cause a quick spike in blood sugar levels.

Avoid eating watermelon right after a heavy meal. The combination of lots of liquids and sugars on top of a full stomach can lead to bloating, gas, and a feeling of heaviness.

Interestingly, a study published in the American Journal of Hypertension found that daily watermelon consumption may help lower blood pressure in overweight adults or those with hypertension. This effect is thought to be due to citrulline, an amino acid found in watermelon that helps relax and widen blood vessels.