AOC3 and obesity due to melanocortin 4 receptor deficiency: Since methylxanthines are clearly endowed with anti-obesity properties [20,21], it could be hypothesized that a SSAO/VAP-1 inhibition by methylxanthines could mediate their tendency to reduce body-weight and fat, alongside their well-known antagonism at adenosine receptors and their inhibition of phosphodiesterases reported to occur in the fat-cells of treated obese rodents [22].