Are aquatic exercises a possibility? If you must not bear any weight, an aqua belt for flotation can provide you with a good workout option. There are also a lot of entry level core exercises from the Pilates world that can help you keep the core strong so that you will be in much better shape once you have healed completely and are ready to EASE into exercise again.
Of course, all the recommendations about nutrition are very valid, and I like Joanne’s suggestion about some resistance exercise with bands.
I wish you good luck for your recovery.