The researches reported that heavy children who had lost weight had kept the kilos off better through weight maintenance follow-up, but even that hadn’t been terribly successful over two years.
The less-than-perfect results underscore the challenge in fighting the U.S.'s obesity epidemic. About 34 percent of American children are overweight.
A team led by researchers at Washington University School of Medicine in St. Louis found that obese children who lost weight kept it off if they were in a maintenance program, but its effectiveness waned over time.
The research involving 150 overweight 7- to 12-year-olds is one of the first large-scale studies to evaluate the long-term effects of weight-loss maintenance strategies in children.
The study, which appeared in Wednesday's Journal of the American Medical Association, also is the first to look at whether heavy kids benefited from being encouraged to play with more physically active peers, cope with teasing, and develop an improved body image.
"We know from the adult field that the biggest challenge is not losing weight - it's keeping it off in the long term," said lead author Denise Wilfley, who heads the weight management program at Washington University.
Kids face the same struggle, she said.
The researchers studied obese youngsters from 1999-2004 at a university clinic in San Diego, where Wilfley used to teach. The children weighed at least 65 percent more than their recommended weight. All of the children in the study also had at least one parent who was overweight.
Each child and parent went through a five-month weight-loss program that set goals and emphasized healthy eating and exercise. They were also counseled by behavioral therapists.
On average, after five months, the children lost about 11 percent of their weight. They were then randomly assigned to one of three groups for four months.
One group was given no further instruction. Another group focused on self-monitoring and vigilance and used other behavior skills, trying to lose weight right away if they regained it.
In the third group, the youngsters were guided into play dates that involved physical activity and healthy eating; they were encouraged to make friends with more physically active peers. They also were counseled on body image and how to cope with teasing.
Researchers checked progress after one year and again after two years.
Those in the behavior skills and social groups were better able to keep weight off in the short term than those who had no intervention. However, the effects waned somewhat during follow-up. The kids left to their own devices regained their lost kilos, and then some, after two years.
The best outcome was for socially adept children who were encouraged to change their playmate networks. Most of those children were able to maintain nearly the same weight they had after the weight-loss program.
More work needs to be done to combine the best of the approaches, Wilfley said, perhaps extending the time spent teaching skills to maintain weight.
The alarming number of obese children means researchers have to develop better ways of helping them lose and keep the pounds off, Wilfley said.
She plans to pursue the idea that spending time with healthy and physically active peers can help children control their weight over the long haul.
Dr. David Ludwig of Children's Hospital in Boston praised the study's family-based effort. However, he said it was not large enough to "make a confident, definitive statement about which approach is better" at maintaining weight loss.
Terry Huang, childhood obesity director at the National Institutes of Health, which funded the study, said the social group's better results are exciting.
"It's not enough to focus on behavior modification," he said. "We have to start looking at obesity in the social context."
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