title: Greater than predicted decrease in energy expenditure during exercise after body weight loss in obese men.
abstract: This study was performed retrospectively to investigate whether exercise energy expenditure (EE) measured during a standardized treadmill protocol (4.5 km/h at 0% grade) falls below predicted values after body weight loss in obese men. A reference equation was established to predict net exercise EE in a control sample of 83 obese individuals (27 kg/m(2)< or = body mass index <45 kg/m(2)), using age, fat mass and fat-free mass as independent variables. This equation was then used to predict net exercise EE in another group of 11 obese men before and after a 15-week drug-based weight loss programme that was coupled with energy restriction [-2929 kJ/day (-700 kcal/day)]. Body weight and body composition were determined by hydrodensitometry. Net exercise EE, insulin, leptin, 3,3',5-tri-iodothyronine and free thyroxine were measured after an overnight fast at baseline and 2-4 weeks after the end of the programme, when subjects were weight stable. Body weight was significantly reduced (-11%; P <0.01) at the end of the weight loss programme. At baseline, measured net exercise EE was similar to that predicted from the regression equation [19.6 and 19.8 kJ/min (4.69 and 4.74 kcal/min) respectively; not significant]. However, after the end of the intervention, measured net exercise EE was significantly below the predicted value [15.5 and 17.3 kJ/min (3.71 and 4.14 kcal/min) respectively; P <0.01]. The difference between the predicted and the measured fall in net exercise EE was significantly associated with changes in leptin concentration ( r =0.79, P <0.01), even after correction for changes in fat mass and insulin. These observations suggest that net exercise EE falls below predicted values after body weight loss. In addition, this greater than predicted decrease in net exercise EE was associated with changes in leptin.
authors.affiliation: School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada K1N 6N5.
authors.forename: Eric
authors.initials: E
authors.lastname: Doucet
authors.forename: Pascal
authors.initials: P
authors.lastname: Imbeault
authors.forename: Sylvie
authors.initials: S
authors.lastname: St-Pierre
authors.forename: Natalie
authors.initials: N
authors.lastname: Alméras
authors.forename: Pascale
authors.initials: P
authors.lastname: Mauriège
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Després
authors.forename: Claude
authors.initials: C
authors.lastname: Bouchard
authors.forename: Angelo
authors.initials: A
authors.lastname: Tremblay
mesh_terms: D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D001823:Body Composition; D004734:Energy Metabolism; D015444:Exercise / Q000502:physiology*; D005260:Female; D005277:Fenfluramine / Q000627:therapeutic use; D006801:Humans; D007328:Insulin / Q000097:blood; D020738:Leptin / Q000097:blood; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000188:drug therapy / Q000378:metabolism*; D012189:Retrospective Studies; D017367:Selective Serotonin Reuptake Inhibitors / Q000627:therapeutic use; D018709:Statistics, Nonparametric; D013974:Thyroxine / Q000097:blood; D014284:Triiodothyronine / Q000097:blood; D015431:Weight Loss
chemical_list: D005277:Fenfluramine; D007328:Insulin; D020738:Leptin; D017367:Selective Serotonin Reuptake Inhibitors; D013974:Thyroxine; D014284:Triiodothyronine