The Influence of Age the BMI and All-Cause Mortality Association: A Meta-Analysis.
Level 3 - non-randomized controlled study
Meta-analysis of observational cohort studies
PubMed 29188887 · doi:10.1007/s12603-016-0837-4
What was done
Researchers conducted a two-stage random-effects meta-analysis of cohort studies spanning community-dwelling adults aged under 65 and 65 years or older to compare BMI ranges associated with lowest all-cause mortality across age groups.
What was found
The meta-analysis included 8 studies with 370,416 total participants (306,340 aged <65 years and 64,076 aged ≥65 years). In adults aged ≥65 years, mortality risk was elevated at BMI levels below 22 (BMI 21.0–21.9: HR 1.05, 95% CI 1.03 to 1.07), a pattern not observed in younger adults. In adults under 65 years, mortality risk increased starting at BMI 28.0–28.9 (HR 1.13, 95% CI 1.00 to 1.29), while mortality did not increase significantly at BMIs above 23 in older adults.
Why it matters
Standard healthy BMI guidelines (18.5–24.9 kg/m²) may be overly restrictive for older adults, who experience higher mortality at the lower end of that range, suggesting age-specific target BMI thresholds may be warranted.
Limits
The analysis relied on 8 observational cohort studies, which are subject to residual confounding from smoking, pre-existing chronic illness, and unintentional weight loss. Cause-specific mortality, body composition (fat mass versus muscle mass), and baseline health status details were not provided in the abstract.
Cited by
- supports Carrying a small amount of extra body weight can be protective against mortality and frailty as people age.