I'm an acct mgr/sales rep for pepsi, about two years ago I had been so stressed from work and started getting sick more frequently and had a huge drop in weight(which might have been from being sick). My brother had also passed away a few months before this.
I went to the doc because I had lost near 20lbs and after several months it had not come back. My doc told me that it was due to stress, and I needed to manage it better and he provided some classes for me to help me with my brother passing away(which I never took).
Less than a month later my boss lightened up my work load, and I had more time to deal with personal issues. Since those two years I have gone from 125lbs to 205lbs(on my heavy days), (I know some are going to ask bf%, at 14%), so I really think it had to do with work related stress, and not managing any personal issues which also played a stressful role in my life.
Studies now show that the body does 2 things when dealing with stress.
First is producing adrenalin, the 2nd being cortisol. I think its safe to say that since I have always been skinny in the past that I doubt my body was doing the 2nd, and more of the first. So, maybe it has to do with the individual. They also say that smoking causes cortisol levels to increase, but so many smokers say that by smoking it lowers their appetite.
IMO, not enough studies have been done to really determine the effects of cortisol. I also believe that everyone deals with stress differently, some gain weight(gain in cortisol), and some lose weight(gain of adrenalin).