Purpose: To examine how body composition changes in different body mass index (BMI) categories among young Finnish men during military service, which is associated with marked changes in diet and physical activity. In addition, this study examined how reported previous physical activity affected the body composition changes.
Methods: Altogether 1003 men (19 yr) were followed throughout their military service (6-12 months). Height, weight, BMI, waist circumference, and waist-to-hip ratio (WHR) were recorded. Previous physical activity was assessed at the beginning of the service by a questionnaire. Body composition was measured by bioelectrical impedance assessments (BIA) at the beginning and at the end of the service. The measured parameters were fat mass (FM), fat percentage (fat %), fat-free mass (FFM), visceral fat area (VFA), lean body mass (LBM), and skeletal muscle mass (SMM).
Results: On average, military training decreased weight by 0.7%, FM by 9.7%, fat % by 6.6%, and VFA by 43.4%. FFM increased by 1.3%, LBM by 1.2%, and SMM by 1.7%. The group of underweight and normal-weight men gained weight, FM, and FFM, whereas overweight and obese men lost weight and FM and gained FFM. FM was most reduced in the groups of overweight (20.8%) and obese (24.9%) men. The amount of VFA was reduced in all BMI groups (38%-44%). Among overweight men who reported being inactive previous to the military service, more beneficial changes in body composition were observed compared with those who reported being physically active.
Conclusions: The lifestyle changes associated with military service markedly reduce fat tissue and increase the amount of lean tissue. These beneficial changes are prominent among previously inactive subjects with high BMI.
1Institute of Health Sciences, University of Oulu, FINLAND; 2Rovaniemi Health Center, Rovaniemi, FINLAND; 3Lapland Central Hospital, Rovaniemi, FINLAND; 4Finnish Defence Forces, Centre for Military Medicine, Lahti, FINLAND; 5Unit of General Practice, Oulu University Hospital, Oulu, FINLAND; 6Department of Sports Medicine, Oulu Deaconess Institute, Oulu, FINLAND; and 7Oulu Health Center, Diabetes Unit, Saaristonkatu, Oulu, FINLAND
Address for correspondence: Ilona Mikkola, M.D., Institute of Health Sciences, P.O. Box 5000, University of Oulu, Oulu, FIN-90014, Finland; E-mail: email@example.com.
Submitted for publication October 2008.
Accepted for publication February 2009.