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