I am not sure about depression caused by weight loss, I thought it was the other way around... getting depressed about weight gain. Regardless, last I heard depression, apart from being bad stuff in general, can make it harder to shed weight.
Interesting note about fat... when I'm not trying (very hard) to eat 3 meals a day I normally basically have a liquid breakfast and lunch then eat a small normal dinner. With the male metabolism I had I stayed slim for 15 odd years with this general method. The key of it I suppose is simply not eating much, but nutrition was always a problem. I've been borderline malnutrition most of my life, and I think I've stunted my physical growth too. Or in fewer words, it is probably not a method to pursue without first doing a lot of research and ensuring you keep yourself healthy.
Sodas are really good at appetite suppression by the way, but they seem to rot out the mouth really good too. Either that or it was the arsenic laced (our goldfishes died in it *snif*) Fernley(,NV) water *wink* I mostly drank sodas though.