Underweight

For children and youth, the definition varies by age:

• Children 0 to <2 years — weight-for-length below the 3rd percentile.²⁴
• Children 2 to <5 years — body mass index (BMI) below the 3rd percentile.²⁴
• Children and youth 5–19 years — BMI below the 3rd percentile.²⁴