LEP and obesity due to melanocortin 4 receptor deficiency: However, several studies suggested that these abnormal leptin levels may be related to the obesity, sympathetic activity, and hypoxia in patients with OSAS.[16–18] Tatsumi et al.[17] indicated that circulating leptin levels were correlated with body mass index (BMI), visceral fat accumulation (VFA), subcutaneous fat accumulation (SFA), apnea–hypopnea index (AHI), sleep mean arterial oxygen saturation, and sleep lowest arterial oxygen saturation.