I think the water loading is based on overloading the body with water on the week of the fight when the training is tapering down so Monday 5 litres water, Tues 5 litres, Wed 5 litres, Thurs 3 litres, Fri 1 litre, Sat no water, weigh in then rehydrate (IV drip if you can get hold of one :))
This technique is quite popular among MMA guys and has proven to work.

Other weight loss tips like no carbs after 5pm, dont mix carbs and protein in one meal, no sauces on food (they have loads of sugar in them esp low fat ones which will cause sugar spikes and induce cravings) and try to have an oat based cereal rather than one from wheat as it is a slow buring carb and will give the body energy throughout the day.

Best one ive found is black coffee, grapefruit and asprin. Not sure why it works so well but does the trick.