I feel your pain. I put a lot of my weight on when I had a broken ankle a couple of years ago. But you're not going to do that, are you? Think of all those muscles in your arms you'll be building when you use crutches for a start. You might not be able to do intense cardio, but you can certainly do some stuff with weights, and you can get your eating right.
Just because you're stuck on the sofa more than normal doesn't mean you have to keep yourself company with chocolate
Anyway, I hope you make a full recovery. I'm amazed at how strong my ankle is now, and even though it's still swollen, there isn't anything I can't do on it.