Importantly, the body mass index of ALL patients correlates with poor prognosis.[36] Any attempt to improve leptin sensitivity will enhance the outcome of ALL patients and prevent recurrence, and the upregulation of leptin receptors by fasting can block the development of ALL.[37] These data suggest that ALL treatments that promote resensitization to leptin might attenuate both obesity and ALL. Here, LEP is linked to obesity due to melanocortin 4 receptor deficiency.