To unravel whether obesity has an impact on myeloid Fas expression, mRNA levels were determined in circulating monocytes of lean and obese human subjects (body mass index (BMI): 21.4 ± 0.5 kg/m2 in lean vs. 45.9 ± 1.1 kg/m2 in obese subjects, p < 0.0001). Here, FAS is linked to obesity due to melanocortin 4 receptor deficiency.