I wrestled in high school and remember spitting all day and running in a sauna suit at lunch to make weight in the afternoon. It was not fun but the weight I had to lose was nothing like what UFC fighters go through. I got to meet UFC fighter Jim Alers a few months ago and had a conversation with him. He fights at 145lbs. According to him his normal weight is around 175lbs meaning he has to lose around 30lbs for each fight. Aler’s large weight cut is fairly common in combat sports.
Buzzfeed had an entertaining video about what it’s like to have to cut weight.