I don't know. I've been limiting myself to ~400 kcal. About half of the time this is chicken, veg, and whole-wheat noodle soup. That's still a reasonable size portion, and I guess has some vitamins but I'm not a vitamin counter by any means. I do whatever makes me feel good, and this does the trick for me. I used to go to restaurants a lot more, but now hardly ever. And I really do stick to the "if I'm not going to be useful I go home" thing, and fortunately I'm in a group that's fine with it so long is it doesn't affect deadlines. Maybe once a month I'll cave to the urge to eat a big whatever and immediately regret it.