Gotta make sure you're exactly on weight for your weight class bro. You literally can't be .1 pounds over what your designated weight class is or else you're automatically disqualified. So say your class is 126, if you weigh in at 126.1, you're ****** . You can totally be 120 though. Hence the no eating or drinking. (Every tiny bit of anything consumed counts when it's before weigh ins)
I remember spitting in a water bottle for 2 hours straight just to lose .3 pounds so i didnt have to go back into the highschool pool room and run laps with garbage bags on. Not fun lol.