Eivind Aadland, Randi Jepsen, John Roger Andersen, Sigmund Alfred Anderssen
Faculty of Health Studies, Sogn og Fjordane University College, Box 523, NO-6803 Forde, Norway. E-mail: eivind.aadland@hisf.no
DOI: 10.2340/16501977-1786

Background: Direct measurement of physical activity may be critical to revealing its relationship with the change in fat mass over time. The aim of this study was to determine the relationship between accelerometer-determined change in physical activity and change in fat mass in severely obese men and women.
Methods: A total of 49 severely obese men (n = 12) and women (n = 37) (mean age 42. 8 years (standard deviation (SD) 9. 6); mean body mass index 42. 0 kg/m2 (SD 5. 9) participated in a 1-year lifestyle intervention with 4 measurements of physical activity (Actigraph GT1M accelerometer), energy intake (180-item food frequency questionnaire), and body composition. Associations were determined using linear regression analyses.
Results: In the total group change in both duration and intensity of physical activity were independently related to change in fat mass (partial r = –0. 38 to –0. 31, p = 0. 001–0. 007) after adjustment for baseline body weight, gender and change in energy intake. A gender-specific effect of change in physical activity duration was found for change in fat mass (p for change in physical activity duration*gender < 0. 001), where the association was significant in men (partial r = –0. 53, p < 0. 001), but not in women (partial r = –0. 17, p = 0. 149).
Conclusion: Increased intensity of physical activity was associated with loss of fat mass in severely obese men and women, whereas physical activity duration was associated with fat mass loss in men.