I used to always gain weight when I would get injured. Not anymore. I've been injured and off/on running for 3 years. Very little running for the last 6 months. And I have actually lost weight. I know you don't believe this, but it's all about diet (and of course you should cross-train if you can w/your injury--I like the elliptical at a decent resistance, particularly using your arms, for calorie burn but that's just me).
But you can control your weight with diet alone. I've done it. And I used to not do it. Just cut out processed food, eat plain/non-fat yogurt/blueberries/uncle sam cereal for breakfast (add truvia) (1 c./1 c./1/2 c.), then salad for lunch--2 c. spinach, 1/2 c. brocolli, 1/2 c. red peppers, 1/2 c. shredded carrots, 1/2 c. garbonzo or other beans or green peas . . .top with lean grilled chicken breast, palm size, or wild salmon, measure 2 tablespoons light dressing (I like Newman's Own Balsamic if I can't make my own that week), then eat snack similar to breakfast, substitute strawberries, around 4 p.m., or half-whole grain sandwich (I buy special bread with no high fructose corn syrup and few other ingredients from publix deli--this is important b/c you need to eliminate high fructose corn syrup totally from your diet) OR an apple or orange with a small handful of walnuts--snack important otherwise you will be too hungry to make healthy choice for dinner, then for dinner lean protein and two veggies cooked in spray pam, add salt, pepper and other fave seasonings, maybe add a whole grain pasta or brown rice--but measure 1/2 c. serving. You will probably lose weight. I still eat dessert--usually 3 choc chip cookies made from special recipe from superfoods RX. Bottom line is that if dramatically increase your consumption of fruits/vegetables, then add some combo of lean protein, beans, and yogurt, you will either maintain or lose weight.
I'm a 120 pound female, but very active. A male would eat slightly more but not too much, of course depending on activity level IMHO. I feed my husband similar food and he just eats larger portions.
But also portion size is important. Just try to eat until you are 80% full at every meal and snack and don't eat when you aren't hungry.
I had to figure this stuff out b/c of my long-term injury. I read several books on diet that I would highly recommend, including Superfoods RX (tells which fruits/veggies are best, and in what quantity you should eat them for daily for optimal health), The End of Overeating (discusses the sh*t in processed food that keeps you addicted and wanting to eat more than you need), In Defense of Food (kind of random, but interesting about what food to eat)...Superfoods RX was my bible for a while. That book is awesome. The above menu plan basically from that book. It works.