'I weighed 70kg at age 11'

When he was eight years old, Chris' parents divorced and he went to live with his grandmother in Mountain Ash, South Wales. "When Chris and his brother and sister came to me, I spoilt them rotten," admits grandmother Alethea Pritchard.

Chris, who has learning difficulties, wasn't overweight when he went to live with his gran, but that soon changed. "My gran let me eat whatever I wanted," he says. "I had all my favourites, like chips, cheeseburgers, pizza, sausage rolls and cakes."

By the age of 11, Chris weighed 70kg (11st). "He was a real little tub," remembers Alethea. "And he was so lethargic, too. If we walked down to the shops, he would complain that his legs were hurting. He wasn't getting any exercise whatsoever and I became quite worried about him."

Meanwhile, Chris' friends at primary school had started teasing him for being overweight. "It wasn't real bullying, just a bit of friendly teasing," says Alethea.

"But I worried about how things would be at secondary school, especially because he has learning difficulties too. I knew I had to do something about his weight."

Alethea started giving Chris healthier meals at home, but it wasn't long before he was back on the junk food. She decided they needed extra help with his weight loss.

"Not long after that, I found out that there was a weight loss class nearby and they were more than happy to have him," she remembers.

"Chris was the youngest person there, so they made a big fuss of him. He loves going to class. When his weight dropped week by week, everyone would cheer him on. It was the best thing I could have done for him."

Chris thrived on the special diet devised by the weight loss club, which gave him a taste for pasta. "Instead of having burgers and chips after school, he started having lots of pasta and he loved it," says Alethea.

"He was just over 70kg (11st) when he joined, but after a year he'd got down to 55kg (8st 9lb). Now his weight is going up again, but that's not excess weight, it's simply because he's getting taller."

Once a chubby boy with no energy, Chris is now transformed. "I feel much fitter and energetic now," he says. "I wasn't happy before. I knew I wanted to lose weight, but I just didn't know how.

"It wasn't easy, but I did it. Nobody calls me 'fatty' any more, which is great. I'm definitely not going to be overweight again."