Infant malnutrition mainly caused by lack of heat energy is called malnutrition-induced emaciation. Malnutrition-induced emaciation is caused by long-term insufficient food intake, with the prominent feature of long-term energy deficiency or inadequate utilization of food, so that normal metabolism cannot be maintained, and the body can only consume its own body tissues to supply energy to maintain the minimum metabolic needs of life. It is a chronic nutritional deficiency disease with no weight gain or weight loss, stagnation of growth and development, and gradual disappearance of fat. It is an extreme emaciation that is common in infancy, also known as infantile atrophy (infantile atrophy, inanition, athrepsia). Muscle atrophy, mental depression, and easy fatigue. At the same time, the dysfunction of various systems in the body and low immunity create conditions for the onset of many diseases, especially pneumonia and diarrhea in infants and young children. According to different clinical manifestations, it can be divided into: emaciation type, edema type and mixed type; according to the degree of malnutrition, it can be divided into mild, moderate and severe; according to the course of the disease, it can be divided into acute, subacute and chronic PEM. Acute onset is often accompanied by water and electrolyte disorders; chronic cases are often accompanied by multiple vitamins and trace elements deficiencies, and about 3/4 of children are accompanied by zinc deficiency.