Male chest development may be caused by obesity, hormone level disorders, diseases and other factors. 1. Obesity: If patients eat too many calories for a long time, the subcutaneous fat will thicken, resulting in the accumulation of breast fat and enlargement, patients will have chest development. 2. Hormone level disorders: an imbalance in the ratio of androgens and estrogens in the male body will lead to chest development, accompanied by nipple and areola enlargement, painless or localized tenderness, usually associated with diet, irregular work and rest, excessive stress, endocrine disorders or medications. 3. Diseases: When patients suffer from male breast cancer, adrenal gland malignant tumor, neuroendocrine tumors and other diseases, it will affect the level of estrogen in the body, which will promote male chest development. It is recommended that patients go to regular hospitals in a timely manner, under the diagnosis of the doctor, according to the patient’s specific condition, to take targeted treatment.