Parents often contribute to their kids eating disorders more than they realize.  It's the parent's job to ensure healthy eating habits and a positive body image.  I read some articles about adults who have suffered from poor body image because of what they grew up hearing from their parents.  One man told his daughter that she would never be pretty and that she was the fattest ballerina in her ballet recital.  He wanted to toughen her up because he had been made fun of growing up.  I also read a lot of stories about parents, particularly moms, apologizing to their daughters for not giving them a better chest. 
Adults who have low confidence need to be extra careful with what they tell their children.  It's never right to call your kid fat or tell them to lose weight.  If I noticed my nieces were gaining weight, I'd first tell them they were beautiful just the way they are and then invite them out for a bike ride.  To make them feel there is something wrong and and that something drastic needs to be done is not the way to do it. 

My dad was always the Food Marshall.  He commented about everything I ate.  It took me a long time to get over my insecurities about food.  If I did so much as eat a cookie, he'd yell "Whose opening the cookie jar!? "  And it'd be me of course. I can't help if I had a big appetite growing up, and yelling didn't help my situation.  I never felt beautiful or 'skinny enough.'