2. Watermelon is a low-calorie and low-fat fruit, with only 3 1 calorie per 100 grams of watermelon. Eating watermelon can reduce the intake of staple food and help to lose weight. Moreover, watermelon diuresis can help digestion and eliminate edema, which is conducive to alleviating edema obesity. However, even so, if you often eat watermelon in large quantities and do not exercise, it will also lead to obesity.