Hiroki Matsuoka

The present study examined the effect of high protein diet programs (Protein≧2.0 g・kg^<-1>・day^<-1>) for male college weight lifters on weight reduction in preparation for competitions. Body composition (under-water weighing), physical working capacity (muscle strength and maximal anaerobic power output), blood constituents and urinary nitrogen excretion (UN) of five male weight lifters (20±2 years) were measured before and at the last stage of the dieting. The period of dieting was 20 days. They practiced about two hours per day, five days a week, during the diet period. The average daily diet contained 2424 kcal (30.95 kcal・kg^<-1>・day^<-1>) with 163 g of protein (2.1 g・kg^<-1>・day<-1>), 81 g of fat and 250 g of carbohydrate. All vitamin intake (A, B_1, B_2, C) and mineral intake (calcium and iron) in this diet were higher than the Japanese recommended dietary allowance (RDA). After dieting, body weight decreased from 78.33 kg to 75.77 kg and the difference was composed of 1.15 kg of body fat and 1.41 kg of lean body weight (LBW). Blood constituents (Ht, TP, Alb, BUN, FFA) were still within normal ranges despite significant changes. UN was increased significantly, but the difference between nitrogen intake and UN was positive (+7.53 g). The estimated value of the nitrogen balance including fecal nitrogen loss (≦2.6 g) and dermal nitirogen loss (≦2.8 g) was positive (+2.13 g). None of the physical working capacities in muscle strength and maximal anaerobic power output showed significant changes. These data suggested that a high protein diet program for weight reduction in weight lifgters was not effective for maintaining LBW. However, it was indicated that the decrease of LBW was not caused by body protein loss.