If you are hurt bad enough to be med boarded, why doesn't that qualify as having a medical issue that hinders weight loss?

Why is it that if you are hurt bad enough to be med boarded that it doesn't qualify as a medical issue that would hinder weight loss. What I'm getting at is if you have limitations to what you can do and you take away the amount of exercise you can do limited through pain it's a problem. When you go from exercising constantly and eating to maintain the workout then just suddenly stop 3/4 of what you normally do without seeing nutritionists to help the change your body will almost go into store mode?....or what's your thoughts please