Weight-loss induced increase in plasma ghrelin is suppressed by ketosis

Abstract

tion in overweight and obese men. These are preliminary findings of the first phase of a counter-balanced cross-over design training study in which participants were randomly assigned to: (1) moderate-intensity (45% VO2max) exercise group (LIE, n = 5, BMI = 26.2± 1.7 kgm−2; age = 24.8± 0.8 yr); (2) interval high-intensity exercise group (30 s at 90% VO2max followed by 30 s rest), (HIE, n = 5; BMI = 31.6± 5.9 kgm−2; age = 29.3± 2.4 yr) 40-min duration, 3 times per week, for 4 weeks. At baseline and the end of the exercise intervention, VO2max and fat oxidation were measured. Fat oxidation was determined during 30-min continuous exercise at 45% VO2max. During the steady state exercise, O2 and expired gases weremeasured intermittently for 5-min periods and HR was monitored continuously. The mean fat oxidation (gmin−1) and VO2max at baseline for LIE and HIE were 0.16± 0.06 and 0.09± 0.08 gmin−1 and 30.6± 4.2 and 25.4± 5.1ml kgmin−1, respectively. After four weeks of exercise training, the mean fat oxidation and VO2max were 0.16± 0.02 and 0.18± 0.04 gmin−1, and 33.4± 4.8 and 27.4± 4.8ml kgmin−1 for LIE and HIE, respectively. The increase in VO2max was on average 9% for LIE and 8% for HIE, however the change reached significance only in the LIE group (P < 0.05). In contrast, the increase in fat oxidation was significant only for the HIE group (P < 0.05). These preliminary results suggest a differential effect of training intensity on cardiorespiratory fitness and fat oxidation. Despite comparable improvements in cardiorespiratory fitness, highintensity interval exercise may increase fat oxidation during steady state exercise to a greater degree than moderate-intensity exercise training in overweight and obese men.