A state of low-grade, chronic inflammation, as observed in obesity, has been associated with altered leptin levels, impaired immune system, and host defenses: obese subjects are more susceptible to respiratory virus infection, to a greater severity of illness prolonged viral shed, increased viral diversity, and adverse endpoints after diseases, until death (Andersen et al., 2016; Aquino-Junior et al., 2018). Here, LEP is linked to obesity due to melanocortin 4 receptor deficiency.