I haven't tried this specifically in the context of losing weight, but I have something like this problem with alcohol because I can't handle very much of it. No one I've socialised with has seriously noticed (or if they have, particularly cared) that I've been nursing that drink for an hour (they do rib me when I follow up with water, but that's what it takes to stop me getting seriously plastered, and when they're sober they care more about my safety- so I can put up with them ribbing me when they're a bit out of it). The other thing you could do (to a point) is save some of your intake for the night out (for me it's calories- so have a slightly less calorific breakfast and lunch, cut down a bit on the snacks, and then I have a 300-400 extra calories to play with for going out). Or plan your meals out (if you're going to a place with nutrition posted, choose a less damaging option from what's there), or eat before you go so you don't have to have a kebab or who knows what else that's 2000 calories a hit.