Im pretty heavy myself dude. Im 6'3 290 pounds.
I stopped smoking in mid May, had a drug test for a job I desperately needed on
July 14th. About 3 days later they called me back and told me I tested positive for marijuana, so of course I didnt get the job.
I still havent smoked since I stopped in May and I've been taking Niacin pills, drinking all kinds of tea, metamucil, whatever I can get my hands on that I think might help in cleaning me out. A few days ago I've also started working out, trying to sweat as much as possible.

I bought 5 dipstick drug test from e-bay for 8 bucks, they came in the mail in 3 days.
I did some experimenting with them.
I used one and I got a faint line, faint but there.
I used one on my sister who at the time had been clean for a month and her line came out a bit fainter than mine did. Shes also no where near as overwheight as I am.
I used one on my girlfriend who still smokes everyday and she got absolutely no line at all, meaning of course she was very much dirty.
I then used one on my cousin who doesnt smoke at all and her line came out very strong and solid.
I used the last one again on myself and I got a line, but not as solid as my cousins line who doesnt smoke at all.

I dont really have an answer to your question but I just thought id let you know my recent story. It is true THC will hang around your body longer if you have more fat on you.

I also want to wish you the best of luck in your future endevours.
I hope someday the government will make it ok for us to use a natural plant.
Dont you guys just hate government intrusion?