Effect of history of overweight/obesity on health outcomes observed in those in the recommended range of body weight (19–25 kg/m2)

PURPOSE: Studies relating adiposity to health outcome often show that the increased disease risk for overweight/obesity (>25 kg/m2) relative to the recommended range (19–25 kg/m2) tends to attenuate with age. To evaluate whether this may be at least partly attributable to the effect of disease-related weight loss, we examined 1) the prevalence of previous overweight/obesity among those in the recommended range of body mass index (BMI), and 2) the impact of previous overweight/obesity on health outcomes in those in the recommended range of BMI. METHODS: We identified 8,410 adults who were cohort members of the Adventist Mortality Study (1960–1985) and Adventist Health Study (1976–1988), and who provided anthropometric data in 1960 and 1976 on the questionnaires for these cohort studies. Among those in the recommended range of BMI(19–25 kg/m2) in 1976, we then computed the prevalence of “previous overweight/ obesity” in 1960, and, additionally related this weight history to incident and fatal events. RESULTS: We found that among the 4,201 adults who were in the recommended range (19–25 kg/m2) of BMI in 1976, the prevalence of overweight (25–30 kg/m2) or obese (>30 kg/m2) in 1960 was 20.4% (27.2% men; 16.4% women). In age-stratified analyses, we found that this prevalence of previous overweight or obesity among those in the recommended range of BMI substantially increased with age (12.6% for < 65 y; 27.7% for 65–84 years; 36.7% for greater-or-equal, slanted85 years). Among those in the recommended range of BMI at baseline, those with previous overweight or obesity were more likely to have diagnosed diabetes (OR = 2.84 95% CI = [2.11, 3.81]), coronary heart disease (OR = 1.90 95% CI = [1.47,2.47]), and high blood pressure (OR = 1.51 95% CI = [1.26, 1.82]). The weight loss that subsequently classified these subjects in the recommended range was associated with a 41% increase (95% CI = 24% to 60%) in mortality risk. CONCLUSION: Our findings indicate that among adults in the recommended range of BMI, the prevalence of previous overweight or obesity increased with age, and that this weight history increased mortality risk. These findings raise the possibility that, due to confounding by disease-related weight loss, the health benefit of being lean may be underestimated, particularly in the elderly and the oldest old.