I'm not sure what exactly the reason is, it's been well document addict how opiate addicts are strongly associated with high sugar consumption while using and sometimes while on Suboxone and Methadone.  Some doctors suggest maintaining the high sugar levels, because it can help cope with cravings.  But it's important to get up to date with your dentist after using and after years of tons of sugar consumption.  Opiate use isn't the only narcotic that make users crave sugar.  Alcoholics often crave chocolate and other types of sugary snacks, and cocaine users have reported consuming lots of sugar and soda while using.

I remember when britney spears had her drug problem there were many articles saying she was addicted to sugar. That she would always have a lollipop, a frapaccino, a soda. Something with a lot of sugar with her constantly

My aunt has a secret addiciton to speed, shes sober now but at the time she lost a lot of weight. Whenever we would go out to dinner, which we did frequently when we visited her or she visited us, she would always order a desert not a real meal. I guess that could be because of her addiction.

I was reading up on this and most of the people with an opiate problem end up gaining a lot of weight. From the ones I was reading they gained between 20-50 pounds. But as they recovered I guess they stopped eating all that sugar and fattening food and lost it all.