What to do about my HUGE sons?

perhaps they are depresed about their mothers death and turn too food, and then when you take that away it is like you are taking away their mother. or they have the same gland disorder she did. They need to somehow understand what it means to be healthy, one step is to teach them how to value life more, and that way they will want to be healthy and get out of bed for it. I really wish i could help more :/