The watermelon is a perfectly healthy food that will not make you gain weight, since it is rich in important vitamins like A and C and in many inorganic nutrients, completely lacking cholesterol or fats.
To cut a long story short, the watermelon not only has fewer calories than most fruits, but it also contains less sugar.
Furthermore, it contains more water that other fruits. That gives it great advantage, since all foods that are rich in water make you feel full without adding unnecessary calories to the body.
The watermelon has what is called “low calorie density”, making it a great “weapon” in the fight for a balanced diet.