Watermelon Over 92 percent of a watermelon Over 92 percent of a watermelon Watermelon Over 92 percent of a watermelon is water. Watermelons are mostly water — about 92 percent — but this refreshing fruit is soaked with nutrients. Each juicy bite has significant levels of vitamins A, B6 and C, lots of lycopene, antioxidants and amino acids. There's even a modest amount of potassium. Plus, this quintessential summer snack is fat-free, very low in sodium and has only 40 calories per cup. Watermelon is the quintessential summertime fruit. It is a staple at picnics and backyard parties everywhere. You know watermelon is sweet and juicy, but did you know that your favorite warm weather treat is also bursting with healthy benefits as well? Here are thirteen science backed benefits that tell the story of just how wonderful watermelon really is. Source: Flavor Run As far as fruits go Watermelon As far as fruits go, watermelon is one of the lowest in calories / only 46 calories per cup (154 grams). That’s lower than even low-sugar fruits such as berries Source: Health Line