1. Maintaining obesity across adulthood, gaining weight from young to middle adulthood, and losing weight from middle to late adulthood, are all associated with an increased risk of all-cause mortality among community-dwelling adults.
Evidence Rating Level: 2 (Good)
While it is known that high body mass index (BMI) is associated with higher risk of premature death, evidence regarding weight change from young to late adulthood, or middle to late adulthood, in terms of mortality is inconsistent and equivocal. Using data from the US National Health and Nutrition Examination Survey (NHANES), this study aimed to examine the association between weight change from young adulthood to midlife and to late adulthood (defined as ages 25 years, 47 years and 57 years, respectively) with all-cause and cause-specific mortality. NHANES was a prospective cohort study, which collected nationally representative health data between 1988 and 2014. This analysis included participants age 40 years and over at baseline, with 40,052 participants identified and 36,051 participants finally included in the analysis. Measured body weight and height at baseline and recalled weights at young adulthood and middle adulthood stages before baseline were gathered. Primary outcomes of interest were all-cause and cause-specific mortality from baseline to the end of December 2015. Of 10,500 deaths over a 12.3 year mean follow-up period, those moving from non-obese to obese categories between young and middle adulthood had a 22% higher risk of all-cause mortality (HR 1.22, 95% CI 1.11 to 1.33), and 49% had a higher risk of cardiac-specific mortality (HR 1.49, 95% CI 1.21 to 1.83), compared to those who remained at a normal weight. Changes from obese to non-obese BMI was not associated with significant differences in mortality risk in the same life periods, but were associated with an increased risk of all-cause mortality (HR 1.30, 95% CI 1.16 to 1.45) and cardiac-specific mortality (HR 1.48, 95% CI 1.14 to 1.92) from middle to late adulthood; moving from non-obese to obese categories between these latter life periods was not significantly associated with increased mortality risk. Maintaining obesity throughout adulthood was consistently associated with increased risk of all-cause mortality for all life periods. The findings of this study therefore suggest that obesity throughout adulthood, weight gain from young to middle adulthood and weight loss from middle to late adulthood are associated with an increased risk of mortality; maintaining normal weight throughout adulthood is likely associated with the greatest benefit.
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