THE EFFECTS OF ENDURANCE EXERCISE WITH AND WITHOUT A REDUCTION OF ENERGY-INTAKE ON FAT-FREE MASS AND THE COMPOSITION OF FAT-FREE MASS IN OBESE WOMEN

Objective: The objective of this study was to evaluate the effects of endurance exercise on fat-free mass and nitrogen balance, with energy restriction or with energy intake to meet non-exercise needs in obese women. Design: The study was a 14-week metabolic control study with a 2-week baseline period for dietary stabilization followed by a 12-week period of exercise (E) with or without energy restriction (D), E or D + E. Setting: Metabolic research unit of the Western Human Nutrition Research Center. Subjects: Ten obese women between the ages of 19 and 37 years volunteered as subjects. Body weight ranged from 19% to 41% I BW and body fat was 31-40% of body weight. Intervention: Women were as signed to either an energy-restricted or energy-'adequate' group so th at group means for weight, body fat, FFM, predicted VO2max and RMR wer e similar. Data were polled for the 2-week baseline period and in 3-we ek intervals during the intervention period. Results: The data indicat ed that E had a slower rate of weight loss and a lower loss of FFM tha n D + E. Nitrogen balance was more positive in E than D + E. Negative N balance occurred in the D + E group when blood was drawn. There was no decrease in N excretion to compensate for blood losses. N balance f or E was positive throughout the study. Conclusion: Changes in FFM, as sessed by total body electrical conductivity, were different from the results obtained by classic nitrogen balance. This suggests that losse s were due to fluid losses, which were confirmed by deuterium dilution procedures. This study demonstrated that body protein stores remained intact during periods of increased energy expenditure and dietary res triction in obese women.