But OP, they are being made ill and damaged by being fat. I'm not talking about side effects of meds or something wrong with them, but only taking in more calories than they expend.
Isn't it very similar to passive smoking? A responsible adult looks out for their children. If you are raising a fatty then a) you're telling them it's okay to disrespect their body b) you're taking years off their life.
I absolutely is calories in versus calories out. It doesn't have to be fried food. Although I have skinny genes, I could eat mashed potatoes all day long and would choose them over chips, chocolate etc. most people would become fat if they ate the calories I did. Having said that, I run / cycle for a couple of hours most days.
If your child's fat then make them exercise more or feed them less. Simple! Really, really simple.
If medication is increasing an appetite (not decreasing metabolism), then eat filling but lower in calorie foods. It's still simple. Chunky children are still being harmed.
As for neglect, as in "fail to care for properly", then yes, it is. You still care for them, but not enough to keep them as healthy as possible.
Parents nowadays seem afraid of tough love.