Has anyone avoided gaining weight back while recovering from a surgery?

Hi everyone, 

I lost 70 lbs slowly from the age of 15-21 (roughly 10 lbs a year) through calorie counting and distance running. I recently tore my meniscus and go in for surgery tomorrow. Post-op looks like 6 weeks non weight bearing and then PT for a few months, hopefully I will be back running around November or December

I’m really scared that I will gain weight while sedentary and recovering from surgery. Like, it’s my #1 worry. When I brought it up, the doctor was much more concerned about functionality and recovery than weight, which is super frustrating since I really need some guidance around food. I’ve been counting calories for the past seven years, it’s the only thing I know how to do. I spent so many of my formative years doing CICO (along with staggered maintenance breaks + maintaining my current weight for about a year) that I couldn’t eat intuitively if I tried. I have no idea what to do with food unless I can see the numbers. 

I’m worried if I restrict myself too much that I will compromise my healing, and I’m already devastated to have to stop running for so long. I’m worried that if I just eat to “fuel myself” (whatever that means) that I’ll gain weight back, which is also a nightmare.

I have no idea what to do.