Associations between body mass index and subjective health outcomes among older adults: Findings from the Yilan study, Taiwan

Previous findings on the associations between body mass index (BMI) and subjective health outcomes among older adults are inconsistent. The aims of this study were to explore the associations of BMI with health-related quality of life (HRQoL), self-rated health (SRH) and happiness among older adults. This study was part of the Yilan study, which was a community-based survey conducted in the Yilan city in Taiwan. A total of 3722 older adults were randomly recruited during 2012–2016. HRQoL was measured using the Short Form-12 Health Survey physical component summary (PCS) and mental component summary (MCS) scores and SRH and happiness were also evaluated. By hierarchical regression, after adjusting for covariates, compared with normal-weight participants, overweight did not have significantly different PCS scores (B = 0.20, 95% confidence interval [CI]: −0.45 to 0.85, p = 0.546) but obese had significantly lower PCS scores (B = −0.97, 95% CI: −1.68 to −0.26, p < 0.0001); overweight and obese participants had significantly better MCS scores (B = 1.00, 95% CI: 0.40 to 1.61, p = 0.001 and B = 1.22, 95% CI: 0.60 to 1.88, p < 0.0001, respectively); overweight participants had significantly higher SRH scores (B = 1.08, 95% CI: 0.16 to 2.00, p = 0.022) but underweight had significantly lower SRH scores (B = −2.88, 95% CI: −4.81 to −0.95, p = 0.003); overweight and obese participants had better happiness scores (B = 1.55, 95% CI: 0.45 to 2.66, p = 0.006 and B = 1.68, 95% CI: 0.49 to 2.88, p = 0.006, respectively). In conclusion, compared with normal-weight individuals, overweight individuals had better mental HRQoL, SRH and happiness but underweight older people reported poorer SRH and obese reported poorer physical HRQOL but better mental HRQoL and self-rated happiness.