Estrogens may also have a role in mediating glucose–insulin homeostasis in women and estrogen deficiency is associated with an increasing risk of obesity, the metabolic syndrome and type 2 diabetes.29 In postmenopausal women, the administration of estrogen can improve glucose homeostasis, insulin sensitivity and lipid profile.56, 57, 58 Studies using estrogen replacement in ovariectomized mice have shown that estrogen protects against fatty liver and may improve pathway-selective insulin resistance.28 This evidence concerns the gene INS and obesity due to melanocortin 4 receptor deficiency.