IL1B and obesity due to melanocortin 4 receptor deficiency: It has been reported that mice with IL-1 receptor antagonist deficiency experience a decrease in fat mass.1 Moreover, abnormality of IL-1 and IL-6 in mice causes severe early-onset obesity.6 Several studies have investigated the association between IL-1B C-31T polymorphism and obesity in humans.7,8 Strandberg et al7 reported that IL-1B C-31T polymorphism did not correlate with fat measurements.