What advice do you have for those recovering from an injury who want to avoid weight gain?

First, eat adequate protein and hydrate well. This stabilizes blood sugar, helps with satiety and hunger, and promotes healing. It’s also important to eat according to your activity. If you usually exercise regularly and are active but your injury is preventing you from moving much you need less calories overall and probably less carbs than you usually have. Then, do let your injury heal and rest as needed, following any instructions from your provider, but don’t use the injury as an excuse not to exercise at all. If you have an upper body injury you can usually walk or even jog and do leg and core strengthening exercises. With a lower body injury you are able to do upper body exercises and you are often able to modify cardio, walking or cycling instead of running for example.