I didn't gain weight I didn't lose weight. I just survived.My Crossfit journey only started several years later after I had suffered a compleer physical exhaustion in autumn 2014. One of the physical therapists who took care of me during the physical reconditioning was a Crossfit athlete and suggested I tried thinking I would like it. And boy did I ! 
When I started I was in constant pain (muscles, tendons, bones, everything) for 2 months. Eventually my body adapted and today I am training 8 to 10 hours a week and am very rare sore. And still thrilled by the journey !
So if cancer was for anything, it took part in leading me to Crossfit ! ;-)

When I went through treatment for a Stage 3 cancer, I was told to "eat whatever I felt like eating", obviously with the thought that the serious chemo I was undergoing would inhibit my appetite. With simple carbs and crap foods, I actually GAINED weight while going through treatment. Wish I knew then what I do now. There's no doubt in my mind that my diet inhibited my recovery, and though I am "cured" there are still issues I have to deal with even 15 years later.