Underweight

Underweight

The underweight range according to the body mass index (BMI) is the white area on the chart.
Specialty	Endocrinology

Human body weight
Part of a series on
General concepts Obesity (Epidemiology) Overweight Underweight Body shape Weight gain Weight loss Gestational weight gain Diet Weight management Overnutrition Childhood obesity (Epidemiology)
Medical concepts Adipose tissue Classification of obesity Exercise paradox Genetics of obesity Metabolic syndrome (Epidemiology of metabolic syndrome) Metabolically healthy obesity Obesity paradox Set point theory
Measurements Body adiposity index Body mass index Body roundness index Body fat percentage Body Shape Index Corpulence index Lean body mass Relative Fat Mass Waist–hip ratio Waist-to-height ratio
Related conditions Diabetes (Type 1) Eating disorder (Anorexia • Bulimia • Binge eating disorder) Food addiction Hyperthyroidism Malnutrition RED-S Starvation (Starvation response) PCOS
Obesity-associated morbidity Arteriosclerosis Atherosclerosis Fatty liver disease GERD Gynecomastia Heart disease Hypertension Obesity and cancer Osteoarthritis Prediabetes Sleep apnea Type 2 diabetes
Management of obesity Anti-obesity medication Bariatrics Bariatric surgery Dieting (List of diets) Caloric deficit Exercise (outline) Liposuction Obesity medicine Weight loss camp Weight loss coaching Yo-yo effect
Social aspects Comfort food Fast food (Criticism) Fat acceptance movement Fat fetishism Health at Every Size Hunger Obesity and the environment Obesity and sexuality Sedentary lifestyle Satiety value Social determinants of obesity Social stigma of obesity Weight cutting Weight class

Underweight is a term describing a person whose body weight is considered too low to be healthy. The definition usually refers to people with a body mass index (BMI) of under 18.5 or a weight 15% to 20% below that normal for their age and height group. While obesity is a major public health concern in many developed nations, being underweight can also carry significant health risks and is a primary cause of mortality in developing countries.