I can't see this helping a fat-ass at all.  They'll be expecting a miracle cure-all without putting in any effort.  If they must have something then it'd be better giving them stimulants, but again, it's a fat-ass you're dealing with and any benefit will be short term (I'd hate to be around a fat-ass hopped up on stimulants; the verbal diarrhoea would be torrential).  If you're not going down the total abstinence route, then buprenorphine is far superior than naltrexone for managing opiate addiction.  Something that potentially takes weeks to work isn't going to be first choice for an addict when there's something that works in hours.