Indeed, when TgsAnk1.5 mice were nourished with high fat-containing food, a protocol known to lead to obesity with 60–80% of the resulting weight gain being attributable to body fat59–62, the weight gain of WT and TgsAnk1.5/+ mice was comparable, and both glucose tolerance and insulin response were similar in TgsAnk1.5/+ compared to WT mice. Here, INS is linked to obesity due to melanocortin 4 receptor deficiency.