The influence of age on the BMI and all-cause mortality association: a meta-analysis

Objectives: To assess BMI range with the lowest mortality for those aged <65 years and those >65 years, utilising cohort studies that spanned the entire adult age range. Design: A two-stage random effects meta-analysis of studies that reported mortality in cohorts both ≥65 years and <65 years. Setting / Participants: Community living adults aged ≥65 and <65 years. Results: Eight studies were included with a total of 370 416 subjects (306 340 aged <65 years; 64 076 ≥65 years). In the older age group, mortality risk increased at BMIs lower than 22 (BMI range 21.0-21.9: hazard ratio (HR) (95% confidence interval (CI)): 1.05 (1.03, 1.07)), which was not seen in younger adults. In the younger group, mortality increased from BMI range 28.0-28.9 (HR (95% CI): 1.13 (1.00, 1.29)), but mortality did not tend to increase significantly in the older group at BMIs above 23. Conclusion: The recommended healthy weight range is appropriate for younger and middle aged adults but a higher BMI range should be recommended for older adults based on mortality.