Dieting is very hard. I only lost a little, and the weight returned eventually. I think some people gain weight easier than others thanks to their genes. For now, my goal is not to cross the obesity line because I can't go on a harder diet or exercise plan.
I suppose it returns to how far you are willing to go for your current health. Your work does seem like a possible root of your unhealthy lifestyle, so I wonder if there is anything you can do about that. Maybe you can also consult the professionals to find out more about why you can't lose weight the way you want.