Dear Sid:
I'm not a long termer but I am a long distance runner. In the last 3.5 years I've run 6 marathons, 5 fifty mile races, and I've done 100 miles in 24 hours on a track twice and 152 miles in 48 hours on a track. I've gained weight doing all of this! I recently started losing by working out with weights and exercising (sits ups, lunges, etc) Perhaps if you try the weight training and exercising that will help you.
Good Luck,
Maureen