Watermelon when eaten in moderation is healthy for you but eating too much watermelon can be bad for you.
Too much watermelon may cause weight gain which is not healthy but if you eat a few servings of watermelon everyday then you should not have any issues.
But if you consumed more than a few servings of watermelon everyday then it could become a problem but you'd likely get sick of eating the watermelon before you did get any health issues or weight gain.
Too much watermelon can cause you to experience side effects such as nausea, diarrhea, indigestion and bloating.
If you're experiencing all of those side effects or even just the diarrhea or bloating then you're eating too much watermelon and should slow down on the amount of watermelon that you eat.
However the watermelon does provide you with nutrients as well as vitamins which is healthy and beneficial for your health.
The watermelon is also a hydrating food because it contains a lot of water so you can prevent dehydration by eating watermelon.