In contrast, in a study measuring a wide panel of cytokines in humans, no significant differences in IL-1β, IL-8, IL-12, IL-2, IL-4, IL-5, IL-10, and IL-13 concentrations were found 3 months after RYGB in 15 women with obesity, which was attributed to the invasive nature of the surgery51. Here, IL13 is linked to obesity due to melanocortin 4 receptor deficiency.