Physical Activity Attenuates Aging-related Weight Loss: A Longitudinal Analysis
Loretta DiPietro, PhD, MPH
Yale University School of Medicine and
The John B. Pierce Laboratory, New Haven, CT.
Weight loss is associated with several functional and metabolic disorders in older age. Unfortunately, there are no longitudinal investigations of this relationship using multiple assessments of physical activity and body weight. We determined longitudinally the effect of baseline physical activity on the rate of weight change over 7 years in a large cohort of older people. We hypothesized that higher levels of baseline physical activity will attenuate the rate of weight loss during the follow-up in this older cohort. Subjects were older respondents to the Yale Health and Aging Study (N=2,434) who were over age 65 y (MeanąSEM=74ą0.13 y). Physical activity was measured by self-report in 1982, and a total physical activity index score (range = 1 to 12) was created from four questions pertaining to the frequency of walking, gardening, sports, and exercise. Body weight was self-reported annually from 1982 through 1988. Total activity score was then categorized into tertiles of high, moderate, and low physical activity. Data were analyzed using random regression modeling that adjusted for the influence of age, sex, height, baseline body weight, race, current smoking, functional status, and chronic conditions. Baseline cross-sectional analyses revealed a strong inverse association between attained weight and age (p<0.001). On average, the entire cohort experienced a weight loss (6.31+0.45 lbs.) over the 7-year follow-up; however, those in the high physical activity tertile experienced a significantly smaller weight loss (4.56+0.57 lbs.) than those in the moderate (7.74+ 0.95) or low (7.54+0.91) tertiles (p<0.05). In the random effects regression modeling, weight decreased linearly with increasing age (b=-1.75+0.13; p<0.001); however, this relation was modified substantially by physical activity level (b=0.23+0.06; p<0.001). Those people in the high physical activity tertile lost 0.46 lbs less per year of age compared with those in the low tertile. Indeed, the rate of weight loss with agewas attenuated by higher physical activity. Physical activity appears to play a key role in the maintenance of body weight in older individuals, thereby minimizing the loss of both metabolic and functional reserve.
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