Is the joint pain causing weight gain or weight gain causing joint pain?
Inflammation can trigger more inflammation. Some inflammatory chemicals actually block hormone sensitive lipase, a hormone that helps you burn fat. The more inflammation you have, the harder it can be to lose the weight. The more weight you carry, the more those joints will hurt.
I remember carrying my 35 pound 1 year old strapped to my belly for 2.5 miles one morning. By the time I got home, my toes, knees, ankles, hips, and back were all achy in a way I had never felt. This must be what it is like to carry all of this extra weight and try to exercise!