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This study was published in the Japanese Journal of Sports Nutrition, vol. 11, 2018, pp. 16-24.

We conducted a one-week, short-term weight reduction program involving exercise intervention and diet control that limited the menu to low- or high-carb food high in protein, and examined the effects on the athletes' body composition.

The subjects of the study were 11 young, healthy adults (male: 7, female: 4) who belonged to a college sports club and trained five or more days a week. The subjects were randomly assigned to a low-carb diet group (6) or a high-carb diet group (5). The program duration was set to seven days, during which subjects in both groups did a 40-minute slow jogging exercise twice a day in addition to their daily training. Meals were designed based on the health tourism diet control program, prepared by registered dietitians three times a day (ideal body weight × 20kcal/day). The protein intake was set to 1.4 to 1.5 g for every kilogram of body weight, and the percentage of carbohydrates was set to 30% for the low-carb diet group and 50% for the high-carb diet group. Subjects were encouraged to hydrate regularly to prevent dehydration. Furthermore, as the study was also conducted to provide nutrition education to the college athletes who were on a diet, the meals were prepared with mainly ingredients and ready-made food available at convenience stores and 24-hour supermarkets to make it easier for the students to prepare similar meals for themselves.

Through the program, subjects in the low-carb diet group and high-carb diet group were able to reduce their body weight by 1.9 kg and 1.8 kg, respectively, and their lean mass was maintained, as a result of combination of a one-week weight reduction program (their routine) and the health tourism program (unusual for them). A short-term weight reduction program that combines daily exercise and diet control and does not involve dehydration may become an effective way for athletes to improve fitness and performance.