I realize this might be blog material, however in the interests of helping a fellow bluelighter... I just wanted to let anyone on methadone maintenance who's gained significant weight and/or anyone who's have severe issues with constipation know - orlistat may help you lose weight, and it most likely will make you have regular bowel movements again. Every morning since I've started taking it, I've taken a massively satisfying dump. I don't feel bloated like I used to anyone. In terms of the weight loss, apparently I've lost 3 pounds (I started taking it 5 days ago), but it could be from the regular bowel movements.
Now for the bad news - it's expensive and insurance usually won't cover the Rx version ($180 for a 1 month/90 capsule supply if taken 3x daily) although the OTC version is much cheaper from what I hear (but we don't have it in Canada). Also, I recommend you start off slowly (take just 1 per day) because of the side effects which may include flatulence with an oily discharge (which is undigested/unabsorbed pure fat) as well as mild-moderate cramps when having a bowel movement. You'll be farting a lot, guaranteed.
It's not recreational and it's pricey, but other than having either a blow or meth habit along with your methadone, I find this stuff actually helps with 2 side effects of MMT which I've tried other numerous products for ranging from fiber supplements to natural/synthetic laxatives for the constipation and also ranging from a healthy diet + daily exercise to "ephedra free" weight loss supplements.