MODERATE DIET RESTRICTION ALTERS THE SUBSTRATE AND HORMONE RESPONSE TO EXERCISE

Substrate and hormone responses to submaximal exercise were studied in 10 overweight women (119-141% ideal body weight) to learn if a modera tely restricted diet would influence the responses. Subjects consumed diets with adequate energy (ADEX), N = 5, or low energy (LDEX)-50% red uction in energy, N = 5. Three times during the 12-wk study, blood was drawn before and immediately following exercise; results were combine d since there were no differences between replicates. Postexercise fre e fatty acids and glycerol increased to 465 +/- 27 mg.1(-1) in LDEX bu t only to 245 +/- 19 mg.1(-1) in ADEX. Postexercise insulin increased to 129 +/- 13 pmol.1(-1) in LDEX, but did not increase in ADEX. Postex ercise growth hormone increased to 10.5 +/- 1.0 mu g.1(-1) in ADEX but only to 6.6 +/- 1.0 mu g.1(-1) in LDEX. AU postexercise increases wit hin diet groups were highly significant (P < 0.0001), and the postexer cise responses between diet groups were also different (P < 0.01). Res piratory gas exchange indicated that both groups increased fat utiliza tion during exercise, but diet restriction altered postexercise hormon es so that fat mobilization and utilization might be inhibited. The po stexercise recovery period should be studied further to determine whet her diet restriction results in a sustained altered hormone pattern th at would curtail lipolysis and possibly limit body fat loss.