By Branwen Jeffreys
Health correspondent, BBC News
Kacey Gibbs is a bright and very lively four-year-old, and like most children of her age is constantly on the move.
Kacey was grossly overweight
On the day I met her she was racing around her grandparents' garden in the sunshine, chatting non-stop.
What makes her stand out is her height and size.
As a result of becoming obese when she was still a baby, Kacey has had a premature growth spurt and is now the height of an average 10-year-old and still weighs five stone (31.7kg).
Kacey's weight began escalating when she was barely six months old.
In the red book given to every parent to chart their child's development you can see the point when Kacey quite literally went off the scale.
Her mother Nadine was terrified to see her baby girl ballooning almost visibly.
"I was scared, worried - because the weight gain was so fast. It wasn't like a couple of ounce, it was like two, three pounds every week.
"And it was getting so fast her breathing was getting bad - she had bad asthma, running around she was getting so breathless."
By the time Kacey was 18 months old she weighed more than three stone.
Her parents could barely lift her, and Kacey wouldn't fit in the child seat of a supermarket trolley.
A whole team of doctors carried out a range of tests which failed to find any underlying medical cause for her condition.
Nadine became increasingly distressed and worried about her daughter, as no-one else in the family had shown the same tendency to rapid weight gain.
Kacey has slimmed down
On holiday at the age of two Kacey looked visibly bloated and large.
The turning point came when Kacey was two.
Her parents decided they had to control what she was eating much more closely.
Nadine drew up a list of healthy foods and told Kacey she had to choose off her special list of "princess" foods.
A typical lunch might now be a bowl of soup with a slice of bread, and a piece of fruit.
Nadine says what prompted them to act was thinking about Kacey's future.
"If we hadn't had cut down on everything she eats - by the time she was eight, Kacey would have been about eight and a half or nine stone.
"It completely frightened me. When you're seeing your only daughter and she's running and getting breathless and you can hear the breathing. She couldn't climb things - it was choking, extremely upsetting to see her like that. "
Gradually over the last two years Kacey's weight has stayed almost stable and she has grown into it.
Her mum hopes that will continue and by the time Kacey is reaching her teenage years her height and weight will be much closer to the average child.
By taking control of Kacey's food her parents have transformed their daughter's future.