The first disease that can result from excessive weight loss is anorexia nervosa, because excessive weight loss tends to strictly and harshly control the amount and type of food intake, which over time can cause a high incidence of anorexia nervosa. The second disease is fatty liver, because in the process of weight loss a large amount of fat is mobilized and transported to the liver for decomposition, if the degree of weight loss is too serious, it will let too much fat accumulate in the liver, and cause a high incidence of fatty liver. The third type of disease is the decline in resistance, because excessive weight loss can cause a lack of many nutrients, including protein, vitamins and minerals, which has a negative impact on resistance, which can lead to a decline in resistance and lead to a high incidence of infectious diseases.