Metabolic health is more closely associated with decrease in lung function than obesity

Objective Previous studies have evaluated the link between metabolic syndrome and obesity with impaired lung function, however findings have been controversial. We aimed to compare lung function among subjects with different metabolic health and obesity status. Methods Total 10,071 participants were evaluated at the Health Promotion Center in Seoul St. Mary’s Hospital between January 2012 and December 2014. Being metabolically healthy was defined as having fewer than three of the following risk factors: high blood pressure, high fasting blood glucose, high triglyceride, low high-density lipoprotein cholesterol and abdominal obesity. Obesity status was defined as body mass index (BMI) higher than 25 kg/m². Analyses of pulmonary function were performed in four groups divided according to metabolic health and obesity: metabolically healthy non-obese (MHNO), metabolically health obese (MHO), metabolically unhealthy non-obese (MUHNO), and metabolically unhealthy obese (MUHO). Results Metabolically unhealthy subjects were more prone to decreased lung function compared with their metabolically healthy counterparts, regardless of obesity status. When multinomial logistic regression analysis was performed according to quartiles of forced vital capacity (FVC) or forced expiratory volume in 1 second (FEV₁) (% pred), after adjusting for age, sex, and smoking status, odds ratio (OR) for the lowest FVC and FEV₁ (% pred) quartiles were significantly higher in MUHO subjects (1.788 [95% CI, 1.531–2.089] and 1.603 [95% CI, 1.367–1.881]) and lower in MHO subjects (0.768 [95% CI, 0.654–0.902] and 0.826 [95% CI, 0.700–0.976]) with MHNO group as the reference, when OR for highest FVC and FEV₁ quartiles were considered as 1.0 Conclusion Metabolic health is more closely associated with impaired lung function than obesity.