INS and obesity due to melanocortin 4 receptor deficiency: Studies have demonstrated that saturated, but not unsaturated, FAs induce insulin resistance likely through stimulating inflammation and increasing ceramide biosynthesis in muscle and adipose tissue.[20] Unlike FFAs, whose saturation impairs insulin sensitivity, our data suggest that increasing membrane PL saturation improves insulin sensitivity and protects mice from diet induced obesity, challenging the conventional notion that saturated fat is always harmful for the body.