Underweight

An underweight person is a type of person whose body weight is considered too low to be healthy. Underweight people have a body mass index (BMI) of under 18.5 or a weight 15% to 20% below that normal for their age and height group. An underweight person is a type of person whose body weight is considered too low to be healthy. Underweight people have a body mass index (BMI) of under 18.5 or a weight 15% to 20% below that normal for their age and height group. A person may be underweight due to genetics, metabolism, drug use, lack of food (frequently due to poverty), eating disorder, or illness (both physical and mental). Being underweight is associated with certain medical conditions, including anorexia, type 1 diabetes, hyperthyroidism, cancer, or tuberculosis. People with gastrointestinal or liver problems may be unable to absorb nutrients adequately. People with certain eating disorders can also be underweight due to lack of nutrients/over exercise.