Sophie Anderson was a healthy 11-year-old primary school pupil who "loved her food".
But, just one week after she joined her fellow Year 6 pupils in stepping on the scales, a letter was sent to her home with graphs attached which said she was at risk of being overweight.
The young girl became anorexic and withdrawn as her weight fell to less than four stone.
With her major organs on the brink of shutting down, she was only saved after being force-fed through a tube in hospital.
Now aged 13 she is recovering and has appeared on Daybreak to speak out against the "ridiculous" decision to weigh youngsters at school as part of the National Child Measurement Programme.
Sophie said: "It’s ludicrous to weigh children at that age because before puberty you get a bit of puppy fat to prepare you for a growth spurt.
"I think that’s very misleading and potentially very damaging for a child to be warned about their future weight at that time when they already becoming self-conscious about their appearance. I really believe it should be stopped.’
The Norfolk teenager, who appeared on ITV’s Daybreak programme yesterday, said all the children at her school compared the letters and talked about it in class which only made things worse.
She said: "I had been a completely happy child but from around this time I started becoming more self-conscious about my body. The letter was certainly part of it. I am also a perfectionist, which makes you more susceptible to anorexia."
"I started off on a diet and it just progressed from there. I started losing weight rapidly.’
After being force fed to save her life, Sophie spent several months at an adolescent psychiatric unit to combat the mental effects of anorexia, before being discharged.
Hundreds of children have been sent letters informing them they are overweight or obese since the controversial child-measurement programme started in 2006.
Health campaigners say it is vital to help warn parents about the dangers of obesity. NHS figures show the number of children admitted to hospital with obesity-related conditions has risen four-fold in a decade.
But Sophie says that schools also need to talk to children about eating disorders, saying: "We need to teach girls that it's okay to love yourself."
What do you think? Do schools need to warn parents about the dangers of obesity? Or is so much focus on children's' weight unhealthy? Let us know in the Comments Box below.