advice on how to keep a loved one on track with healthy eating and no alchole without obviously interfearing

[mothersmilkandherchickenseggs]

following on from another post i wrote dh and i have begun a new lifestyle he needs to lose alot of weight and we both could do with generally being healthier we have both committed to agym membership. But dont tell him this but i worry he might fall of the wagon food and booze wise i just wondered if anyone out there has any good ideas of how to cunningly keep him on track.
thankyou guys x

Anyone? please