it's a better idea to take some snack foods and some healthy foods with you--or pick them up when you get there. For instance, fruit is easy to store for a few days, and most veggies will stay nice for a couple of days (like carrots and celery). bread is a no-brainer. Buy a nice loaf get some nut-butter and jelly (all fruit jellies are good). Also, hummus and pitas will keep for a few days too. So, you have lots of options.
that way, you have good healthy food around that is also satisfying.
ALSO, please, please please please please--whether you're going to a conference at a hotel or a college do=hickey--please please please please please call the organizers, explain your diet, and ask what the options are for you so that you can prepare yourself.
For example, at my university (penn state), they had lots of vegetarian and vegan options while i was there (veggie burgers and veggie dogs available every day, tofu every day, lots of vegetarian bean dishes, plus a whole fresh salad bar every day). Even though i wasn't a vegetarian in college, it was easy enough to be one! I ate a lot of veggie meals in college. I also had food in my dorm, because we had a minifridge and microwave that we could use.
But, organizers can often give you this information, or at least help you meet your needs!