Obesity has well-known negative effects on health, but being underweight can also be harmful. Even though less than 2% of Americans over the age of 20 are underweight, having a body mass index (a measurement of your body fat about your weight and height) under 18.5 can result in weakened immunity, hormonal and fertility issues, as well as nutritional deficiencies that can cause anemia and osteoporosis[1]. Furthermore, evidence from studies suggests that being underweight raises the risk of dying[2].
