Effects of 2 wk of GH administration on 24-h indirect calorimetry in young, healthy, lean men

• Published in: American journal of physiology: endocrinology and metabolism 2005-12, Vol.289 (6), p.E1030-E1038
• Main Authors: Hansen, Mette, Morthorst, Rikke, Larsson, Benny, Flyvbjerg, Allan, Rasmussen, Michael Hojby, Orskov, Hans, Astrup, Arne, Kjaer, Michael, Lange, Kai Henrik Wiborg
• Format: Article
• Language: English
• Subjects: Adult; Body Composition; Calorimetry, Indirect; Double-Blind Method; Energy Metabolism - drug effects; Fatty Acids, Nonesterified - blood; Fluoresceins; Human Growth Hormone - administration & dosage; Human Growth Hormone - blood; Humans; Insulin-Like Growth Factor I - analysis; Male; Ouabain - analogs & derivatives; Placebos; Time Factors
• ISSN: 0193-1849; 1522-1555
• DOI: 10.1152/ajpendo.00124.2005

1 Institute of Sports Medicine, 2 Team Denmark Test Center, Bispebjerg Hospital, Copenhagen; 3 Medical Research Laboratories, Aarhus University Hospital, Aarhus; 4 Medical and Science Development Projects, Novo Nordisk, Bagsværd; and 5 Department of Human Nutrition, The Royal Veterinary and Agricultural University, Frederiksberg, Denmark Submitted 18 March 2005 ; accepted in final form 20 July 2005 The present study was designed as a randomized, double-blind placebo (Plc)-controlled study to determine the effect of 2 wk of growth hormone administration (GH-adm.) on energy expenditure (EE) and substrate oxidation in healthy humans. Sixteen young healthy men were divided into two groups. The study consisted of two 24-h measurements (indirect calorimetry), separated by 2 wk of either Plc or GH injections (6 IU/day). At baseline, no significant differences were observed between the two groups in any of the measured anthropometric, hormonal, or metabolic parameters, neither did the parameters change over time in the Plc group. GH-adm. resulted in a 4.4% increase in 24-h EE ( P < 0.05) and an increase in fat oxidation by 29% ( P < 0.05). However, a decrease in the respiratory quotient was only observed in the postabsorptive phase after an overnight fast (0.84 ± 0.1 to 0.79 ± 0.1, P < 0.05). Furthermore, lean body mass (LBM) was increased by GH-adm. only [62.8 ± 2.5 kg (baseline) vs. 64.7 ± 2.4 kg (after), P < 0.001]. In conclusion, GH-adm. increases 24-h EE, which may be partly explained by increased LBM. Furthermore, GH-adm. stimulates fat combustion, especially in the postabsorptive state. energy expenditure; fat oxidation; growth hormone; insulin-like growth factor I; metabolism Address for reprint requests and other correspondence: M. Hansen, Institute of Sports Medicine, Copenhagen, Build. 8, Bispebjerg Hospital, Bispebjerg Bakke 23, DK-2400 Copenhagen NV (e-mail: mh19{at}bbh.hosp.dk )