Don’t bring up what you overheard with your parents. It seems to me you have much to lose and little to gain. Instead, go back to school and prove their fears wrong. Get good grades–it’s clear you can do it, since you already have. Do exercise so that you don’t continue to gain weight and watch the snacking. I don’t think you are overweight at all (and I tend to think many people are) but this is something that is easier to prevent than reverse. Anyhow exercise is a good study break. If you return home at Xmas with more good grades and not much weight gained and they start talking like this to your face, then a family discussion might be in order but for now I think it would likely just antagonize them and the last thing you want is for them to refuse to pay for your school. The longer you keep up your grades, the less they have to be concerned about.