Grandmothers often try to reassure parents of fat children by saying they will "grow out of it," but that is an old wives' tale, a study shows.

A team led by Lee Ga-young, a professor of family medicine at Inje University Busan Paik Hospital, chose 190 overweight children aged 6 to 11 in South Gyeongsang Province as test subjects in May 2003. The team watched the changes they underwent for two years.

In choosing the subjects, the team focused on the top 15 percent of the most obese children, while setting standards based on the average height and weight of all children in the same age group throughout the country.

Degrees of obesity were assigned to a tiered scale, based on the body-mass index calculated by dividing weight by the square of height and taking the difference between boy and girls. The results showed that the children became fatter as they grew.

"Many Koreans believe that if you gain weight in childhood, you'll grow bigger and taller later," Lee said. "But the findings of this study show that the belief is wrong."

The findings were published in the Korean Journal of Family Medicine last month. "Childhood obesity will give you a bad physical constitution that could be the basis of all adult diseases, so parents should watch their children's obesity and rectify it at all cost."

Once children become obese, hormone secretion is disturbed and body cells gradually injured. As a result, they face a high risk of abnormal bodily functions as they grow.