Breast fat and development can be distinguished by clinical physical examination and laboratory examination. 1. Clinical physical examination: obesity breast enlargement is caused by the increase of subcutaneous fat, touch the breast, no hard lumps in the nipple, soft texture; breast development is not only the increase of subcutaneous fat, the increase of subcutaneous glands, nipple can be touched under the obvious nodules, touch with the hand, the texture of the hardness, touching with pressure and even the feeling of pain. 2. Laboratory tests: you can go to the hospital to do bone age, sex hormone six, ultrasound, such as breast development hormone levels rise, bone age in advance, the thickness of the endometrium thickened, the diameter of the follicle in the ovary will also become larger, the indicators of abnormality indicates that breast development. Fat is the whole breast is enlarged, this fat has no hard lumps, soft texture, do ultrasound shows no breast tissue, only fat tissue. Therefore, it is easier to distinguish between breast development and obesity.