are you able to do any type of physical activity, or do you have pain issues that led to your being prescribed methadone eventually?
i ask only because i don't want to give you advice if you're a chronic pain patient or have an ailment that prevents you from being physically active.
also, what does your daily food/liquids intake look like? what do you typically eat throughout the week?
i'm a pilates instructor and i help people with both weight and pain related issues regularly. i'm happy to answer any questions you may have. my (limited) understanding of methadone is that it can cause both water retention and slower metabolism.