Actually the last 18 months has seen a vast improvement in my health after about 25 years of not having good health. I am in total remission from Ulcerative Colitis and I suspect that this has something to do with my weight gain but certainly not all.
I have been talking to some health professionals and when I relate my exercise/weight loss story to them they acknowledge that the body gets used to exercise then conveniently don't want to debate what happens when exercise is used for weight loss and the body becomes used to it thus negating the effects. It is funny how all conversation ceases on that point. I know exercise has other side benefits but as a tool to lower weight it is limited, I have a friend who has always been super fit and exercises by cycling many kilometres a day or runs etc, enters cycling competitions etc and he is gaining weight as he gets older!