Compared to participants with a normal pulmonary function test, those with a restrictive impairment were more likely to be a current smoker, to have an elevated concentration of cotinine, to have low levels of high-density lipoprotein cholesterol, to have an elevated concentration of C-reactive protein >3 mg/l, and to have an elevated prevalence of diagnosed diabetes and obesity. This evidence concerns the gene CRP and obesity due to melanocortin 4 receptor deficiency.