In the final days before a fight, a boxer may be in a position where he has to drop five pounds or more over a period of just a few days in order make the prescribed weight. This often happens when a bigger fighter is dropping down in weight class. In the case of a 145-pound fighter who must fight at 140 pounds, he will try to engage in serious workouts to lose the weight. One of the most popular ways to do this is to wear a plastic sweat suit while running, lifting weights or skipping rope. These are high-intensity activities that burn quite a few calories on their own and even more when wearing a plastic suit because that piece of clothing promotes perspiration and the loss of weight. This activity is quite dangerous because of the prospect of dehydration but many boxers engage in this activity.
Many boxers who are in the final stages of losing weight will do anything they can to help their cause. Someone who is in the final hours before weigh in will often chew gum constantly, carry a cup with them and spit into the cup. The loss of saliva can actually help the boxer lose ounces in the final hours before weigh-in. Chewing the gum helps promote the build-up of saliva.
This is similar to wearing a plastic sweat suit because it promotes excess perspiration. Some boxing trainers are known to turn the heat up to as high as 140 degrees and have their boxers work out and spar under these stultifying conditions in an effort to cut weight in the final days and hours before a fight. This is not advisable and the boxer must be monitored at all times to assure his safety.