INS and obesity due to melanocortin 4 receptor deficiency: The importance of local and systemic effects of obesity is supported by many studies and involves the following potential mechanisms: increased levels of estrogens, excessive aromatization activity of the adipose tissue, over-expression of pro-inflammatory cytokines, insulin resistance, adipocyte-derived adipokines, hypercholesterolemia, and excessive oxidative stress contribute to the development of BC in obese women, especially in postmenopausal women [72,73,74].