In this study, sudden weight loss effects on pulse of boxers is aimed to searched. Amateur boxers of Sakarya Boxing Club and 22 volunteered athletes in 2011, still operating, have participated in this research. The athletes ages, body weight, sports ages and heights are measured with Cooper test results when they were over twice of their normal weight and by suddenly reducing them to their competition weight. In our study; a stopwatch, tape measure and for record a Toshiba brand laptop computer are used as data collection tools. The obtained data was analyzed by using Paired Samples Test in SPSS 17,0 statistics program. When the data, that is obtained from Cooper test results when they were over twice of their normal weight and by suddenly reducing them to their competition weight, is compared, a significant different was found between the first trial of pre-training and the second trial pre-traning. A significant different was found between first trial during the training and the second trial during training. There is not found a significant difference between the first trials after 1 minute of training and second trials after 1 hour of training. There is not found a significant difference between the first trials after 1 hour of training and second trials after 1 minute of training. As a result of this study, it is seen that there is a significant impact on sudden weight loss of heart rate. Accordingly, instead of sudden weight loss of our athletes, body weight should be reduced gradually three months prior to the competition in the long term. Since this weight loss will be accomplished in harmony together with the organism, athlete's organism does not enforce. When we obtain weight loss of our athletes in long term by applying appropriate loadings and nutrition, our organisms adapt to this situation quickly and there will not be overload on our organisms. In this process, we can see that the athletes have had an appropriate preparation period. (C) 2014 The Authors. Published by Elsevier Ltd.