In addition to storing energy, fat secretes hormones, participates in the body’s inflammatory response, and affects endocrinology, thus causing a number of related diseases, of which diabetes is one of the more representative ones. As early as 2014, weight loss metabolic surgery has been included as one of the standard treatment options for diabetes in China. At this stage, most of the weight loss metabolic surgery used to treat diabetes is gastric bypass surgery, which is known as the “gold standard” procedure for the treatment of diabetes. Gastric bypass surgery maintains blood glucose at a lower level by reducing body weight, reducing diet and absorption, and improving hormone secretion, so that diabetic patients can complete blood glucose regulation through the residual pancreatic secretion capacity, so the treatment effect is more stable than drug treatment. In addition to diabetes, polycystic ovary syndrome is also a common complication in female obese people. The hyperinsulinemia formed by obesity, especially central obesity, can over-stimulate the synthesis and secretion of steroid hormones in ovarian tissues, and the increase in local androgen production can lead to atresia of mature follicles and polycystic ovary syndrome, resulting in anovulation or sporadic ovulation. This symptom can be significantly improved after weight loss metabolic surgery. Recently, studies have also shown that bariatric surgery can also affect thyroxine secretion, which may be a new treatment for thyroid decline. The effect of bariatric surgery on the endocrine system is the result of a combination of factors. In addition to weight loss, good lifestyle habits can play an important role in improving the endocrine system.