I run into this when traveling and am up by 3 a.m. and often don't get to bed until 3-4 a.m. ... I DO eat more often, but try to work in more fruits and veggies, which, often don't hold me as much as I want them to, unless they're paired with some protein. (apple/banana and some peanut butter, etc.) ... I try to drink a lot - but not just water - tea, juice mixer with diet sprite, etc. - something different even tho i don't drink much juice.
As you say, one day won't make/break you - but if you know you'll be discouraged, don't weigh in for a few days afterward.
Stay busy is my best hint. I'm not hungry sometimes when awake for a long time but if I'm waiting in an airport and everyone is eating cinnabuns, hot dogs, fancy schmancy coffee drinks, I think, hmmmm... i should be too!