CELLULAR BIOENERGETICS, WORK PERFORMANCE, BODY-COMPOSITION AND PSYCHOLOGICAL INDEXES AMONG WOMEN IN A DIET-EXERCISE PROGRAM

Forty moderately obese women enrolled in a 10 week study employing a l ow-fat, rotating energy diet, nutritional supplementation and aerobic walking. Energy intakes rotated between 2.09 and 6.27 MJ (500 and 1500 kcal) on alternate days. On 2.09 MJ days, women consumed meal substit ute tablets each hour for the first eight hours of the day (totaling 2 3 gm carbohydrate, 4 gm fat, 3.2 gm protein), followed by whole food s nacks and dinner On 6.27 MJ days, subjects consumed diets of less than 20 percent fat and engaged in 20 to 30 minutes of aerobic walking. Nu trition supplements were taken daily. 34 women completed the study. Ur inary ketones did not change throughout the study. Anthropometric and psychological parameters were measured at weeks 1, 3 and 10. Body comp osition, assessed by bioelectrical impedance, showed mean declines in body weight of 5.8 kg (p < .001), body fat of 3.6 kg (p < .001), perce nt body fat of 2.4 percent (p < .001), and fat-free mass of 2.1 kg (p < .001). Improvements in reported sense of wellbeing (p < .01), percei ved energy (p < .001) and body image (p < .OO1) were noted. Skeletal m uscle energy function and work output was assessed using a computer-in tegrated arm ergometer and magnetic resonance spectroscopy to quantify the concentrations of inorganic phosphate (Pi), phosphocreatine (PCr) and intracellular pH (pHi) under resting and exercising conditions. P re- to post-study increases in maximum arm strength (16.8 to 22.2 kg; p < .001) and total work output (191 to 282 joules; p < .001) were fou nd. No changes over the study period were found in Pi/PCr ratios or pH i under either rest or exercise conditions. Although the impact of spe cific program components were not identified, the data suggest improve d metabolic function in conjunction with favorable changes in psycholo gical indices and body composition.