Watermelon is definitely one of the favorite fruits for those who are on a diet, simply because they do not contain a lot of calories. One full cup of watermelon contains around 46 calories total, so it does not have a significant number of them.
Another reason why watermelon is such a healthy snack and fruit overall is because it contains no saturated fat, cholesterol, or total fat. It does however contain 0.1 grams of polyunsaturated fat as well as monounsaturated fat, which is still not a significant amount at all. Those who tend to count calories will be able to rest assured that the watermelon they enjoy does not contribute very much to their caloric intake.