This study aims to suggest the guide line for weight category sports(Taekwondo, Judo, Wrestling, Weightlifting, and Boxing) who have to lose weight to pass weigh-in before games. Reference data was collected from RISS, Medline, PubMed, SciELO and effects of short term weight loss on physiological variables(body composition, physical fitness, blood components, oxidative stress and hormone, immune function) were analyzed. Also, weight loss procedures for weight category sports athletes were analyzed in details. The results of the research are as follows: weight category sports athletes prefer short term (3~5 days) weight loss methods (3~5%) with dietary control, sweating and exercise. Physical changes caused by the loss in body weight, fat-free mass, and BMI, however, do not affect body fat percentage. Different changes of physical strength element depend on weight reduction period. In short term weight loss method, anaerobic exercise capacity, muscular strength, and reaction time partially decrease and affect staying power. In contrast, long term weight loss method do not affect aerobic and anaerobic exercise capacity. Furthermore, most of previous studies show that blood component change has negative effect on body water balance, stress-related hormone, and immune function. In conclusion, short term weight loss method negatively affects athletic performance of weight class competition athletic. Therefore, careful long term weight loss methods are recommended with dietetic consideration to prevent dehydration during weight loss period. Excessive weight loss on lightweight athlete should be prevented by institutional basis as well.
