Is a 13 year old that is 36kg underweight?

To determine if a 13-year-old weighing 36 kg is underweight, we need to consider their height, as body mass index (BMI) is a more accurate measure. Generally, for a child, a BMI below the 5th percentile is considered underweight. If the child's height is significantly below average for their age, then they may be considered underweight. It's best to consult a healthcare professional for an accurate assessment.