Yeah im well aware of that. But teenage obesity is not nearly as much of a problem as e.g. adult diabetes (~33%), breast cancer and colorectal cancer. Teens don't watch their peers struggle in and out of the car in the hospital parking lot for surgery. We need followups to adolescent health education in adulthood.
20% of teens in America are obese. I think you underestimate how much of a problem it is. Here's a source https://www.cdc.gov/obesity/data/childhood.html