One of the richest common sources of lycopene — not just "water and sugar" as its reputation suggests.
Watermelon's reputation as "just water and sugar" undersells it — at over 90% water by weight, it's also one of the more concentrated dietary sources of two specific, well-studied compounds.
Watermelon is actually one of the richest common sources of lycopene, the same carotenoid covered in our tomatoes profile — pink and red watermelon varieties carry meaningfully more than yellow ones. It's also a strong source of citrulline, an amino acid studied for supporting blood flow and, in some small trials, exercise performance and post-exercise muscle soreness.
Lycopene concentrates most heavily in the fully ripe, deep-red flesh closest to the rind — a practical reason to choose fully ripe watermelon over less-ripe fruit if the lycopene content specifically matters to you. Citrulline is actually found in even higher concentrations in the white rind than the red flesh, though the rind is rarely eaten in most cuisines.
Given its water content, watermelon delivers real volume and sweetness for relatively few calories — useful context if you're also mindful of the Volumetrics approach to eating covered elsewhere on this site.
Sliced and eaten plain, blended into a savoury-sweet salad with feta and mint, or frozen into cubes for a hot-day snack.
One of the easiest fruits to eat in genuinely large quantities without much sugar impact, given how much of each serving is water.