...the weigh ins the night before? I was watching some boxing today and I seen that both of the fighters weighed in at 115lbs at the weigh ins and the next day when they had the fight they weighed in 15lbs heavier. I seen that Brock Lesnar weighed 265lbs (lie lol) at the weigh ins and weighed in at 285lbs at the fight. How and why do they gain so much weight over night and that not hurt them during the fight?