Abstract
We investigated the association of metabolically healthy (MH) and unhealthy (MU) obesity with incident lung dysfunction. This cohort study included 253,698 Korean lung disease-free adults (mean age, 37.4 years) at baseline. Spirometry-defined lung dysfunction was classified as a restrictive pattern (RP) or obstructive pattern (OP). We defined obesity as BMI ≥ 25 kg/m(2) and MH as the absence of any metabolic syndrome components with a homeostasis model assessment of insulin resistance < 2.5: otherwise, participants were considered MU. During a median follow-up of 4.9 years, 10,775 RP cases and 7140 OP cases develped. Both MH and MU obesity showed a positive association with incident RP, with a stronger association in the MU than in the MH group (P(interaction) = 0.001). Multivariable-adjusted hazard ratios (95% CI) for incident RP comparing obesity to the normal-weight category was 1.15 (1.05-1.25) among the MH group and 1.38 (1.30-1.47) among MU group. Conversely, obesity was inversely associated with OP because of a greater decline in forced vital capacity than forced expiratory volume in 1 s. Both MH and MU obesity were positively associated with RP. However, the associations between obesity, metabolic health, and lung functions might vary depending on the type of lung disease.