LEP and obesity due to melanocortin 4 receptor deficiency: The purpose of the present study is, therefore, to 1) examine circulating leptin and s-ICAM-1 levels as a representative of inflammatory markers among Japanese male subjects with or without smoking habits, and, then, to 2) understand possible underlying mechanisms on differential leptin regulation under the differential environmental conditions to ultimately try to understand the pathophysiological nature of obesity among smokers.