i know that to go on suboxone you have to not take any opiates , im assuming including methadone.. for 3 or 4 days MINIMUM until you start to take suboxone because it will react very badly with it and cause you to go through the worst withdrawls ever. and when i say ever i mean EVER. like anything youve ever gone through times ten. i wanted to go on suboxone before i went on methadone but my doctor told me that and i decided against it. he told me that most people dont really take those 3 days off of drugs and pretend they have, so when they go most people contemplate suicide. but if you want to do it its your choice, and there are lots of positive aspects to suboxone. if you can go through those 4 days without anything though id just go through more so you dont need anything. as for not gaining weight i think it would be just the same. some people i know dont even gain any weight at all. im on methadone and i was the exact same weight when i started as you were and now im the exact weight as you are now. im at 90 mg and im starting to taper off soon. ive been researching alot and everyone says that when you taper down you will start to loose weight ,so that is a good idea. but i feel your pain my friend, ive tried everything to loose weight and still nothing is cutting it. i hope you find a good solution and if you do, share it with the world. starting with me. i hope ive helped at least a little.