"If those children could sustain the changes in food and physical activity then that would make a [weight] difference in the long term," says lead author Carolyn Summerbell, a professor of human nutrition at the University of Teesside in England.

According to Summerbell, the health programs that are effective for children are those that put some fun into fitness and food. Dance programs based on the latest music are popular with girls, while boys often enjoy martial arts. "They don't want the boring old sports and training that are often in the curriculum," she says.

Likewise, diet change can be accomplished through fun, social events such as healthy eating clubs and interesting food preparation. "The standard boring vegetables, your boiled cabbage, is like circuit training. You need to think how a young mind thinks. A stir-fry and a dance class is great," reports Summerbell.

The updated review, which appears in the July issue of The Cochrane Library, includes 22 studies. That's more than double the number available when the review was originally published in 2001. This is good news, according to the report, because "It is becoming increasingly clear that decision makers need much more information upon which to base policy and program decisions."

The Cochrane Library is a publication of The Cochrane Collaboration, an international organization that evaluates medical research. Systematic reviews draw evidence-based conclusions about medical practice after considering both the content and quality of existing medical trials on a topic.

Studies in this review comprised about 10,000 children in Asia, South America, Europe, and North America. Nineteen studies analyzed school-based programs, one was a community effort aimed at low-income families, and two were family-based interventions targeting normal-weight children of heavy parents.

The review notes that many of the included studies have "methodological weaknesses," including reliance on self-reports of activity levels and eating habits. Summerbell notes that a number of larger, more rigorous studies are currently underway, many funded by the U.S. National Institutes of Health.

Childhood obesity has become an international health priority, as fatty diets and sedentary lifestyles spread across the globe. Severely overweight children suffer a variety of physical and social ills, and they face increased risk of many health problems throughout life even if they grow up to be normal-weight adults.

Summerbell readily acknowledges that the trial programs are "just a drop in the ocean" in terms of all the factors that influence children's health behavior. TV and video games, for example, are here to stay, she says. "It's important to build in time that children can do that and also to build in some time when they can do really fun things around physical activity."

Obesity prevention is "a very complex issue that requires attention to all sorts of variables," observes Sylvia Moore, director of the Division of Medical Education and Public Health at the University of Wyoming. Promoting significant, sustained reduction in obesity-related health problems is "going to take changing the sociocultural environment, so that activity is valued."

Mealtimes should be pleasurable social events rather than eaten on the run. "We need the food industry on our side," Moore adds, pointing specifically to the problem of excessive portion sizes in many packaged and restaurant foods.

Anyone who has tried to maintain a healthy weight knows that sustaining lifestyle changes is the hardest part. The review authors say that not enough is known about the impact of factors such as food availability, financial options for healthier food and activity options, safer play spaces, and school-community partnerships in preventing childhood weight-gain.

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