Help with my grandmother?

From the looks of your picture it seems like you're very young and I take it that you don't have any children either. Would you want for your Grandmother to live long enough to see them? If so you should explain that to her. Tell her you love her more than you usually do. Let her know that its not just her weight or her smell its her life that you're worried about the most. Be as gentle as you can because if she eats to be happy you don't wanna make her upset. If push comes to shove (not trying to be funny) but look up t.v shows or help from the press. The more people know about it the more serious she will get about her health