24 Hr Energy Intake After A Single Exercise Session In Restrained And Unrestrained Overweight Women

Abstract

At rest energy intake (EI) is expected to be lower in restrained than unrestrained eaters. It is unknown however how acute exercise affects appetite and EI in restrained and unrestrained overweight/obese women. PURPOSE: To investigate acute effects of exercise on EI between restrained and unrestrained overweight/obese women. METHODS: Sedentary and overweight/obese women completed one exercise and one control trial following a crossover design. Trials were randomly counterbalanced and of 24h duration each (including overnight at home). Weighed EI record was kept for 2.5 days before 1st trial and was replicated before 2nd trial. In the exercise trial subjects completed an aerobic exercise session at 65% VO2max intensity to expend 1.67MJ. In the control trial subjects rested quietly for the same duration. Appetite was measured throughout trials using visual analogue scale (Flint et al, 2000). Absolute and relative EI (REI) were measured during 3 buffet meals served throughout each trial (day 1 post-intervention dinner and day 2 breakfast and lunch) with covert observation of EI. Cognitive restraint of eating was measured using the 3 factor eating questionnaire and the median restraint score was used for classification. Data were compared by paired and 2 sample t-test. RESULTS: 15 subjects completed the trials, with no attrition. 8 subjects were restrained (R) and 7 unrestrained (UR). Mean values of physical characteristics were not different between groups and trials (Weight (kg): 75.1 ± 10.4 (R), 79.2 ± 12.8 (UR); BMI (kg/m2): 29.5 ± 3.0 (R) 30.7 ± 2.1 (UR); Mean ± SD). Average energy cost of exercise (minus metabolic costs) was not different between groups (R: 1.85 ± 0.27; UR: 1.57 ± 0.25 MJ). No difference between trials and groups was found in subjective ratings of appetite. 24hr EI and REI was not significantly different between groups in either trial. However, REI of UR was significantly lower after exercise than control trial (Ex: 8.52 ± 1.94; Con: 9.96 ± 2.42 MJ/24hrs, p<0.05), while there was no difference in the EI of R between trials. CONCLUSIONS: These novel and preliminary findings suggest that EI in UR females may be affected by a single exercise session while EI in R females remains relatively constant. This may reflect differing levels of cognitive restraint. Further studies are required to confirm these pilot data.