There are two reasons for children’s weight loss, under-absorption or over-consumption, or both. 1. Under-absorption: for example, eating less, insufficient nutritional intake, lack of zinc leads to picky eating, do not love to eat and love to eat snacks, may cause malnutrition leading to weight loss. There may also be some gastrointestinal diseases, such as chronic gastritis, chronic enteritis, Crohn’s disease, etc., the gastrointestinal tract absorption capacity is reduced, no matter how much food to eat is not helpful, most of the nutrients are lost, resulting in the child’s weight loss. 2. Excessive consumption: excessive physical exertion can also lead to weight loss, but this situation is less common. Weight loss is mostly seen in some chronic wasting diseases, such as long-term gastrointestinal dysfunction, tuberculosis, intestinal tuberculosis or tumors. 3. Both: Most of the chronic diseases will lead to mental deterioration and loss of appetite, resulting in the child eating less and consuming more, accelerating the weight loss. Children’s weight loss, there may be other reasons, it is recommended to go to the hospital in a timely manner, improve the examination to clarify the cause of the disease, under the guidance of the doctor to give targeted treatment or treatment.