IL15 and obesity due to melanocortin 4 receptor deficiency: Since Quinn et al.[29] showed that male IL-15tg animals are protected against diet induced obesity, it is possible that the importance of the gut bacterial differences in our three strains of mice become evident when challenged with a high fat, where similar results in improved glucose homeostasis and insulin sensitivity become evident in our IL-15tg compared to B6 and IL-15−/− animals.