ENERGY-EXPENDITURE AND PHYSICAL PERFORMANCE IN OVERWEIGHT WOMEN - RESPONSE TO TRAINING WITH AND WITHOUT CALORIC RESTRICTION

The metabolic effects of exercise training and the influence of a moderate calorie restriction on the training response were examined in overweight women. Ten healthy women, 119% to 141% of desirable weight, completed the 14-week study. After a 2-week stabilization period, in which diets were designed to maintain body weight (BW), five women were assigned to a 12-week experimental program of diet and exercise (D + EX) that included a 50% reduction in energy intake and a program of moderate intensity aerobic exercise 6 days per week. The other five women were assigned to the same daily exercise (EX) and continued to consume the stabilization diet. Periodic measurements of resting metabolic rate (RMR), thermic effect of food (TEF), energy cost of exercise, and predicted maximal aerobic capacity (VO2 max) were obtained, and the respiratory quotient (RQ) was determined during rest and exercise. Body composition was monitored weekly. Tests of strength and anaerobic capacity were conducted. D + EX lost an average of ∼1.1 kg/wk, which was 67% fat, 33% lean. EX lost ∼0.5 kg/wk, which was 86% fat, 14% lean. In both groups, the exercise program resulted in an 11% to 13% improvement in VO2 max and an 8% to 16% decrease in energy expenditure at submaximal workloads. The caloric restriction significantly increased fat utilization during exercise. The RMR declined 9% in D + EX, from 1,550 to 1,411 kcal/d, whereas it was maintained in EX, 1,608 to 1,626 kcal/d. The decrease in RMR observed in D + EX was consistent with the loss of fat-free mass (FFM). Neither diet nor training affected TEF or anaerobic capacity. Hand grip strength decreased in both groups by the end of the study. These results suggest that healthy, mildy obese women are capable of improving their aerobic fitness, and a 50% restriction of energy intake does not adversely affect physical performance. © 1990.