Contest overseas

I have a contest overseas. I live in Chicago and will be flying to hong kong with a 3 hour layover in vancouver,canada. i believe its about a 4-5 hour flight to vancouver and then a 12 hr flight to hong kong. my question concerns will eating certain foods such as carbs or drinking liquids make me retain water when i land. basically what can i or cant i eat on the plane. i leave tuesday morn from chicago and land wed eve. thats with the international dateline change. i lose a day. my contest is friday eve. could i carb up when i land , should i even bother? i know the best scenario would be to leave earlier, but work and finances do not permit, thanks for any help.