Why would you want someone to kill themselves? Also, not everyone thinks as you do. Some people, if you push and push, will sink into a depression and eat more. There are some, who have medical issues that don't allow them to lose the weight. There are others who like being a little "heartier" than others. Is it possible that you have weight issues? Could this be why you are going on and on about it. Is it possible that you want someone to go on and on about it towards you?
You need to learn to accept people for who they are and not what they look like. Kind of like the old proverb, "Never Judge A Book By It's Cover".