Anthropometry and Mortality in Older Women: Potential Survival Benefit of Overweight and Obesity

This chapter examines the reported relationship between body mass index (BMI kg/m2) and other measures of anthropometry, such as fat mass and waist circumference, and the risk of all-cause mortality in older women. The World Health Organization (WHO) and the NHLBI have defined overweight as body mass index (BMI) 25.0–29.9 kg/m2 and obesity as BMI of 30.0 kg/m2 or greater and stated that all individuals who are overweight or obese are at risk for increased morbidity and mortality. The application of this single set of cutpoints to define mortality risk associated with overweight and obesity is controversial, particularly when applied to older women. Some studies support a linear relation while the majority of studies of older women have reported a J- or U-shaped relation between BMI and mortality in older women. Other studies have reported a “flattening” of this J- or U-shape relation between BMI and mortality among very elderly women. The totality of the evidence suggests that the BMI associated with lowest risk of mortality in older women is much higher than in younger women and that it includes overweight and possibly moderately obese women. The WHO and NHLBI guidelines are not appropriate when interpreting BMI levels and risk of mortality in older women, since many of the women categorized as overweight or obese are at the lowest risk of mortality. There does appear to be some survivor effect or protective effect of increased adiposity for risk of mortality in older women. Recent data suggests, however, that the possible protective effect of obesity on mortality may not provide protection against disability. More data are needed to understand fully the nature of the relation between anthropometry and risk of mortality and the link with morbidity and disability. There continues to be a striking lack of information on the risk of increased adiposity and mortality in non-White women. Although there is very little data on other measures of anthropometry other than BMI, BMI is highly correlated with other measures of anthropometry and is an easy and practical method of studying these relationships.