Because you ate something wrong.

There is an enzyme in watermelon, which will synthesize fat when eaten.

Although watermelon is diuretic, its synthetic fat is much more than the weight of edema eliminated by diuresis.

I see

Apples are good things. Eat more apples and cucumbers.

I am a person who refuses to exercise. I lose weight by dieting. If you are interested, leave me a message and we will communicate, hehe.