When deciding what weight class to fight in for Boxing or MMA, it is important to know and understand when you will be weighing in for your match. Most Amateur matches weigh in the same day, sometimes an hour before the actual matches. In this case, you want to choose a weight within 5 lbs. of your walking around weight.
Professional matches are different. For pro matches, one usually weighs in the day before the fight. As a result one can lose 15 to 20 lbs. in water before they weigh in. This is an uncomfortable and sometimes dangerous process, but can be done. After weighing in, you can rehydrate over the next day, to your walking around weight. Most pros weigh in 10-20 lbs. less than what they are fighting at on fight day. You are at an advantage to weigh more than your opponent in a fight, hence why there are weight classes in boxing and MMA.
- Mike "Kujo" Kurzeja, Pro Boxer