LEP and obesity due to melanocortin 4 receptor deficiency: The mechanism is that peripheral adipose tissue can promote the conversion of androgens into estradiol and androstenedione into estrone, while leptin and lipocalin formed in the process of obesity inhibit the level of sex hormones and globulin, so that the level of free sex hormones increases, and a certain concentration of estrogen has a protective effect on bone, and estradiol and estrone can reduce bone resorption [38].