Tubby kids stand a better chance of slimming down and keeping the weight off if their overweight parents try to reduce too, stay away from junk food and praise the children along the way, researchers said Wednesday.

"If you have children who you don't want to eat potato chips, you can't sit in front of them eating Ho-Hos," said psychologist Leonard H. Epstein, head of the University of Pittsburgh's Childhood Obesity Clinic and leader of the research team.Findings published in Wednesday's Journal of the American Medical Association suggest child obesity need not persist into adulthood. Previous research concluded that fat children will become fat adults and that weight lost in dieting programs is typically regained quickly.

In the study, children who participated in a weight-loss program as 6- to 12-year-olds and whose parents took part in similar programs were significantly less obese 10 years later than those whose parents received less training.

In the project, 75 obese children and their parents were randomly assigned to three groups. They were instructed to limit consumption to no more than 1,500 calories a day and follow an aerobic exercise program.

All were asked to attend eight weekly treatment meetings followed by six monthly meetings, then meetings at the 21-month, five-year and 10-year marks.

In one group, both parents and children received praise for losing weight and were trained to praise other family members for changing eating and exercise habits.

In the second group, only the children received praise and were trained to praise family members for weight-control behavior.

Parents and children in the third group received praise only for attending the meetings. They received information about social reinforcement without specific training in how to use the method.

All subjects lost weight initially. At the 10-year mark, the children in the first group were, on average, 7.5 percent less overweight than at the beginning of the study. Those in the second and third groups were 4.5 percent and 14.3 percent fatter, respectively.