High-fat diets, too little exercise and couch-potato culture are contributing to new levels of obesity in young children, British doctors warned on Friday.

Their research, published in the British Medical Journal, found an increasing trend in obesity from 1989-1998 and showed that more children in Britain under four years old are overweight or obese now than ever before.

"A quarter of children at the age of three or four are obese," Professor Peter Bundred, of the University of Liverpool, told Reuters.

Bundred and his colleagues blamed the problem on a lack of exercise, high-fat diets and processed food.

"My solution is basically to encourage children to play. It is a normal part of childhood development and we need to encourage them to do that," said Bundred.

"We also have to be more aware of the food we give them," he added.

Although the figures are based on statistics of British children, Bundred and his colleagues believe they are representative of young children in most developed countries.

"We know that US teenagers have the same or worse levels of obesity than children here... I'm sure these findings are transmittable to most developed countries in the world," he said.

The researchers used the body mass index (BMI), a standard method of measuring obesity, of nearly 36,000 children, comparing them year-on-year.

"We looked at the number of children who were overweight or obese and the change over time. What we've seen is steady year-on-year increase in obesity -- worse in boys than in girls," said Bundred.

Research has shown that obesity in children persists in adult life and carries with it a host of medical problems including an increased risk of asthma, diabetes, heart disease and some cancers.

"We have an abnormal view of what a child should look like," said Bundred. "A chubby child to us is quite a normal child and yet actually a normal child should be quite thin."

(From ChinaDaily)