Association Between Weight And Weight Change Across Adulthood And Risk Of Mortality

Objective: To investigate the association between weight and weight changes across adulthood and risk of mortality.Methods: Study subjects who participated in the US National Health and Nutrition Examination Survey 1988-2014 and aged 40 years or older were included.After excluding those who did not receive physical examination,did not have baseline weight and height measured and have no mortality status,a total of 36051 participants remained in our analytic cohort.Self-reported recalled weight at age 25(defined as young adulthood),at ten years before baseline(defined as middle adulthood)and measured weight and height at baseline(defined as late adulthood)were used to approximate weight change in three time intervals across adulthood: weight change from young to middle adulthood,from middle to late adulthood and from young to late adulthood.When analyzing the association between BMI and mortality,weight status at each time point was categorized into 7 groups as following: BMI<18.5 kg/m2,18.5-19.9 kg/m2,20.0-22.4 kg/m2,22.5-24.9 kg/m2,25.0-29.9 kg/m2,30.0-34.9 kg/m2,and ≥35.0 kg/m2.When analyzing the association between weight change and mortality,five weight change patterns for each interval were defined: stable normal pattern(<25.0 at both times),maximum overweight pattern(25.0-29.9 at either time but not ≥30.0 at the other time),obese to non-obese pattern(≥30.0 at younger age and <30.0 later),non-obese to obese pattern(<30.0 at younger age and ≥30.0 later),and stable obesity(≥30.0 at both times).Cox proportional hazard models were used to calculate hazard ratios and corresponding 95% confidence intervals of mortality associated with BMI at each time point and weight change in each interval.Results: During a mean follow-up of 12.3 years,10 500 deaths occurred.BMI at early adulthood was positively associated with mortality,while the associationbetween BMI at midlife or late adulthood and mortality appeared to be J-shaped or U-shaped.Compared with participants remaining normal weight,those moving from non-obese to obese category from young to middle adulthood had a 22%(hazard ratio 1.22,95% confidence interval=1.11-1.33)and 49%(HR=1.49,95% CI=1.21-1.83)higher risk of all-cause mortality and heart disease mortality respectively.Gaining weight from middle to late adulthood was not found associated with risk of mortality,while changing from obese to non-obese BMI over this period was significantly associated with increased risk of all cause(1.30,1.16-1.45)and heart disease mortality(1.48,1.14-1.92).Nevertheless,compared with stable obesity,losing weight over this period was not found associated with increased mortality risk,while the obese to non-obese pattern from young to middle adulthood was associated with lower risk of all-cause mortality(0.71,0.50-1.00).Maintaining obesity across adulthood was consistently associated with increased risk of all-cause mortality,and the hazard ratio(95% confidence interval)was 1.72(1.52-1.95)from young to middle adulthood,1.61(1.41-1.84)from young to late adulthood,and 1.20(1.09-1.32)from middle to late adulthood.Maximum overweight individuals had a very modest or null association with mortality across adulthood.No significant associations were found between various weight change patterns and cancer mortality.Conclusions: Overweight and obesity at early adulthood,weight gain from young to middle adulthood and stable obesity across adulthood were all found associated with increased risk of mortality.Losing weight from young to middle adulthood may also lower mortality risk,compared with stable obesity.Our research indicates that maintaining normal weight across adulthood,especially preventing weight gain in early adulthood,is important for preventing premature deaths in later life.