Okay, I'm going to assume I'm the only person here who lost weight by no longer exercising
I'm 5'6" and started college weighing 125 lbs and in my freshman year, gained 10 lbs, as a lot of college freshmen do, but I gained all muscle. My water polo coach had us on a brutal conditioning regiment. It definitely made me stronger, faster, tougher, and a much better water polo player (though I also ended up with tons of injuries from over-exertion).
My senior year in college, I was playing water polo again, after time off due to knee surgery, and rowing on a club crew team (all that additional muscle meant I got to sit in the power seat in the women's boat). The combination of long swim workouts and rowing, however, resulted in a pinched nerve in my shoulder. I couldn't swim or row anymore after that.
To make matters worse, I started to get sympathetic nerve inflammation and irritation down my arm and back. No longer swimming also led to the aggravation of an existing lower back injury (this one due to running). Swimming is incredibly good for your back and my swim workouts were about the only thing keeping my back from getting completely out of sorts.
At the worst point, I couldn't bend over to touch my knees, let alone my toes, I couldn't tie my shoes and I had to sleep sitting up in bed. Having suffered a broken nose (twice), a concussion, broken fingers and toes, reconstructive surgery (after the broken nose), knee surgery, and infected wisdom teeth, the pain in my back was easily ten times worse than all of them combined. I was popping an average of fifteen advil a day just to get through the day and I'd routinely spend an hour a day hanging upside down and another hour undergoing electric stimulation to try to reduce the pain.
All the while, I was doing no exercise, of course. Several months of this bad back business and I lost, through muscle atrophy, most of the weight I gained playing college water polo. I'm not quite at the weight I was when I was a college freshman, but I'm pretty close now.
Rac
