Submitted to: American Journal of Clinical Nutrition
Publication Type: Peer reviewed journal
Publication Acceptance Date: 9/18/2001
Publication Date: 2/1/2002
Citation: HUGHES, V.A., FRONTERA, W.R., ROUBENOFF, R., EVANS, W.J., FIATARONE-SINGH, M.A. LONGITUDINAL CHANGES IN BODY COMPOSTION IN OLDER MEN AND WOMEN: ROLE OF BODY WEIGHT CHANGE AND PHYSICAL ACTIVITY. AMERICAN JOURNAL OF CLINICAL NUTRITION 2002;76:473-81. Interpretive Summary: This study examines the 10 year change in body composition (fat mass, FM; fat-free mass, FFM) in 131 subjects initially 60 years of age. FFM declined in men (2.0%/decade) but not in women. Energy expenditure in sports and recreational activity also declined in men and remained unchanged in women. Neither age nor physical activity levels were directly associated with the change in FFM. Weight stable subjects lost FFM while those who gained >5% of their body weight gained FFM (19% of weight gain). FM increases by 7.5%/decade in men and women. Younger women in the cohort increased FM, while women over the age of 70 years lost FM. Low levels of physical activity at baseline or at follow-up were associated with fat mass gain in women only. Even with overall lowered activity levels, lean tissue gain was observed in individuals who gained weight, while the higher activity levels in those losing weight were not sufficient to prevent lean tissue loss over the follow-up period. Given the general recommendations for increased physical activity for all individuals regardless of age, and the findings of this study which document that weight loss is associated with consistently higher levels of physical activity in this older cohort, we must consider that resistance type exercise with its relatively low energy expenditure rates, to be of prime importance when assessing energy balance of the non obese elderly person inclined to lose weight.
Technical Abstract: Background: Estimates of fat-free mass (FFM) and fat mass (FM) changes in the older adult are mostly derived from cross-sectional data. Objective: This study examined the natural longitudinal patterns of FFM and FM change in older adults and explores the impact of baseline and follow-up physical activity patterns, weight change and age in these changes. Design: Body weight (BW), body composition by hydrodensitometry, and sports and recreational activity (SRA) were examined twice, 9.4 +/- 1.4y apart, in 53 men and 78 women, initially aged 60.7 +/- 7.8y. Results: FFM declined in men (2.0%/decade) but not in women, while FM increased similarly in both sexes (7.5%/decade). SRA was higher initially in men and declined more in men over the follow-up period. Baseline age and SRA were inversely and independently associated with FM change in women only. Neither age nor SRA were associated with FFM changes in men or women. Weight stable subjects (<5% body weight change) lost FFM. FFM accounted for 19% of BW in those who gained weight, even in the presence of lowered SRA. FFM loss (33% of BW) was pronounced in those who lost weight, in spite of median SRA levels greater than 4184 kJ/week. Conclusion: Although an overall FM increase was observed, there was an attenuation of this increase in women with advancing age. The average decline in FFM over the follow-up period was small and masked the wide inter-individual variation that is dependent on the magnitude of weight change. The contribution of weight stability (or modest weight gains) or lifestyle changes that include regular resistance exercise to attenuate lean tissue loss with age should be explored.