The effects of light versus moderate exercise added to diet control in a weight reduction program for overweight college women

Abstract

Thirty-nine overweight college women were assigned to one of three weight reduction groups: diet control (DC), DC + low intensity exercise (LX), DC + moderate intensity exercise (MX). All women were tested for VO₂peak and percent fat. The DC included a previously designed nutrition education and behavior modification program held one time per week which prescribed a caloric intake based on body weight to result in a 1000 kcal•day⁻¹ dietary deficit. Exercise groups were asked to also attend three exercise sessions each week. In addition to a warm up and cool down, LX exercised at a heart rate corresponding to 40% of VO₂peak for 35 minutes per session while MX exercised at 70% of VO₂peak for 20 minutes. Exercise durations were chosen to match LX and MX for total exercise caloric expenditure. Heart rates were self-monitored every 10 min and sporadically verified by the exercise leader. At the end of the 8 week program, there was an overall drop out for the three groups of 34%, with the DC group having the highest attrition (50%) relative to LX ( 40%) and MX (20%) groups. VO₂peak did not change significantly after the 8 week program in any group, perhaps as a function of the modest exercise stimulus and/or a sharp reduction in attendance noted in the final 2 weeks. However, an improvement in cardiorespiratory efficiency was indicated by the significant reduction of heart rate at submaximal workload III (MX = -12, LX = -10, DC = -6 bts·min⁻¹ ). A significant mean decrease of 2.93 ml·kg⁻¹·min⁻¹ in VO₂ at the same submaximal workload was noted. All groups lost a significant amount of body weight over the eight weeks. The trend in average body weight loss (DC=4.0, MX=3.6, LX=3.3 kg) was opposite to that of % fat loss (LX = 5.1, MX = 3.9, DC= 2.2%). These differences were not significant but show a tendency for exercise coupled with diet control to enhance fat but not total body weight loss. Thus, the treatment which enhanced fat loss and most strongly enhanced attendance was a moderate intensity exercise added to diet control.