First of all, I don't know if you really want to lose weight because you are fat ... If you are actually thin, there is nothing wrong with your parents always asking you to eat. If you don't eat three meals a day to lose weight, your parents are right.

If you really don't need to eat, you might as well tell your parents directly that you don't want to eat. If your parents think it's a waste, tell them not to do so much in the future. Don't buy so much. Actually, you can't eat too much.