LONDON Britain risks becoming a nation of fatties because more and more primary schoolchildren are becoming obese, researchers said on Friday. One in five nine-year-olds and nearly a third of 11-year-old-year girls are overweight and the tendency often carries into the teenage years and adulthood. "Starting from the age of nine there is a significant increase in the numbers of overweight and obese children at levels that are concerning because they are predictive that the adult population will have increasing levels of obesity and that goes along with major medical problems," Dr. Mary Rudolph told Reuters. The pediatrician at the Leeds Community and Mental Health Trust in northern England said the trend in Britain is consistent with other Western countries. She and her colleagues measured the body mass index (BMI), a standard method of gauging obesity, of nearly 700 children in 10 primary schools between 1996-1999 and compared their findings to expected growth standards. They found a significant increase in the proportion of overweight and obese children between nine to 11 years olds in both boys and girls. Their findings, which are reported in the ****British Medical Journal***, are consistent with other recent studies that have detailed alarming increases in obesity in British children. "We're attributing it, not surprisingly, to diet and a lack of physical activity. Probably the more important factor is the decrease in informal and formal play," said Rudolph. The levels of obesity in young children are increasing at such a rate that Rudolph and her colleagues believe it is a major health issue that needs urgent attention. "Primary schools are a good place to start because the problems tend to start at that age and children at that age are more malleable to lifestyle changes," she said. Parents also need to give their children nutritious foods and must encourage them to do more physical activities. Rudolph also suggested that advertising of high fat foods should not be allowed during children's peak television viewing times. Obesity, which is the biggest health crisis facing many industrialized countries, is linked with an increased risk of asthma, diabetes, heart disease and high blood pressure. Obesity increases with age and also runs in families, but scientists are not clear about how genetics contributes to the condition.