How much stone do you have to weigh to be obese at the age of 12?

Obesity in children and adolescents is typically assessed using the Body Mass Index (BMI) rather than a specific weight in stone. For a 12-year-old, a BMI at or above the 95th percentile for their age and sex is considered obese. This can vary significantly based on height and body composition, but generally, a weight of over 10-12 stone (140-168 lbs) could indicate obesity for many 12-year-olds, depending on their height. It is important to consult growth charts and healthcare professionals for accurate assessments.