try to be a bit careful about what you eat, and cut down on amounts, yes it's hard work getting around on crutches so you will use energy that way, but if youre bored in the house on own all day eating is something to do and if you are used to being quite active you will not get the same amount of exercise. I was an even bigger hefier than usual when I came off crutches after 6 wks. Recovery time will depend on how bad you broke it I guess, mine was very straight forward and my ankle was fully mobile quite soon after the cast came off. Hospital did not offer any physio but I went for a few sessions privately and found simple exercises a huge help in getting the strength and mobility back. And the more you use it the quicker it will recover is my theory-tho I'm no doctor!! Was back doing easy sport within couple of weeks, and hockey training few weeks after that. Went skiing within 12 months too, and had no trouble at all.
Oh, and get your friends to take you out-alcohol numbs the pain, but be careful on slippy floors with crutches!! Hope it's better soon x