I'd imagine ones that are far behind that of any other sport. Probably use the Wrestling model, but a butchered version of it. Hasn't there been instances where Rios was a wreck in the sauna? Floyd and Froch have done the smart thing: Live the life and fight at your walk-around weight. No worries about being depleted/having a bad cut then.
You shouldn't have to cut weight. Whichever you feel best at is what you should be fighting at. Boxing isn't bodybuilding. There is no cutting.
an amateur shouldn't cut much weight because you only have a few hours from the weigh in to the fight (a pro will have sometimes over 24 hrs to replenish). and if you're super new you only need to be at a weight class for tournaments. i haven't looked at the rules lately but its something like up to 7lbs difference between opponents at a club show. you could call it a catch weight, and not an actual weight class. your first few fights you should focus on maintaining skills, getting used to the competition environment, smaller gloves, the ref, etc. don't allow yourself to get beat by the scale.
Also of note for amateurs: when you go to tournaments, you likely fight day after day if you're winning and advancing. I remember a couple guys who cut a lot of weight for a state golden gloves tournament back when I was coaching. First fight, they looked great and easily defeated their opponents. But they had to weigh in again the next day, so that night they go eat and then they're out in the parking lot running around for like an hour. And then again the next day with sweat suits and whatnot. Barely made weight, and looked like zombies -- both lost their second fights and had zero left in the tank.
Most bodybuilders don't cut weight for weight classes. Generally methods I've use to lose water for bodybuilding is to drink huge amounts of water. Upwards of two gallons then cut water about noon before the show. I've lost as much as 11 lbs in a week doing that but wouldn't want to fight anyone.
Interestingly, another tip is try and train where the temperature is 54 degrees F, the body works best at that, dont train in plastics.
