When going out, I try to keep to fish. Starters are usually something like grilled calamari, shrimp, scallops, seared tuna - probably bad for cholesterol but good for the calorie count. If people share starters, that's even better because I tend to just nibble. Always pass on the bread. Scotch on the rocks (just so the ice melts and you don't outpace yourself) and a bottle of wine for dinner. I usually skip dessert and go for scotch or brandy. The only trouble I run into are the people who order huge steaks or pastas and they will obviously out do me for the evening. I used to do vodka and diet soda but the caffeine keeps me up and I find diet sodas make you want to eat more.
For those special "holiday dinners" or anything that involves a buffet line, I would literally eat a full meal a few hours before I go to the event (not lunch). That way, I just have a few drinks, a light salad and nibble on something so I can focus on socializing rather than stuffing myself.
Otherwise, every week I try to take 48 hours (I promise myself 72 hours but it never happens) and do all the healthy stuff - keep meals light, salads, work out, let the liver get some rest etc. I eat out for lunch every day at work so that means time to hit a Japanese place for sashimi or a Chinese place for just the steamed dim sum if the 48 hours happens to fall on a work day. I tend not to drink alcohol at Asian places, mostly because their selection is horrible and I'm not a big sake person so it reduces temptation.
From my peak, I've probably lost 30lbs since practising this. I used to do drink like a mule, go out for cocktail hour, eat and come home and eat dinner. And since I always ate out for lunch and had a huge breakfast; kept going for pastas, steaks, spanish coffees, fruity martinis, etc. I actually believed this radio advert that was saying all business men grow an inch in their waist every x years so you must come to our suit store and buy new suits. But I think I have it under control now. Expense accounts can be a terrible thing.