The formula is pretty straightforward: energy in/energy out. This is the term nutritionists use to describe the intended balance between calories consumed and calories burned. If the level of physical activity is not great enough to burn the amount of calories taken in, weight increases. If this imbalance continues, overweight and possibly obesity result.
Given our fondness for fast food (an ever-growing fondness, due to ever-busier lives) and our tendency to "supersize," it's easy to imagine that caloric intake is the crux of the obesity problem. And certainly it is part of the problem, especially considering the quality of the calories consumed. (Recent evidence indicates that children get a full quarter of their vegetable servings in the form of potato chips and French fries!) But the greater problem lies with the second half of the equation: energy out.
Studies both here and abroad have indicated this is true. The Framingham Children's Study, for example, found that preschool children with low levels of physical activity gained significantly more subcutaneous (beneath the skin) fat than did more active children. In another study it was determined that inactive preschoolers were 3.8 times more likely than active preschoolers to have increased triceps skinfold thickness (the best measure of obesity in children) in follow-up assessments. It's also been found that children who watch more than five hours of television a day are almost five times more likely to be overweight than children who watch two hours or less ? with excessive TV viewing considered to contribute to 60 percent of the risk of obesity in children.
More specifically, in the United Kingdom, while the proportion of overweight or obese children remained the same between 1974 and 1984, there was a marked increase in the following decade. The research, reported in the British Medical Journal, determined the change was due not to increased energy (calorie) intake but rather to a decrease in energy output.
Studies in the United States have made the same determination. An increase in childhood obesity of 20 percent over the last decade (at least one in five American children is currently overweight) has occurred despite a decrease in overall fat consumption and little change in caloric intake.
According to the authors of a research article appearing in the journal of the American College of Sports Medicine, there is one consistent observation that stands out among the studies of energy expenditure in young children. That unfortunate observation is that children under the age of seven seem to expend about 20 to 30 percent less energy in physical activity than the level recommended by the World Health Organization.
Sedentary children? Obese children? Unfit children? They're all a fact of life in today's society. The sad irony is that in today's society we're more "active" than ever ? in terms of "busyness," that is. Perhaps we should get busy becoming more active in the physical sense. Energy out is the key to maintaining an appropriate weight during childhood. As such, exercise (mostly in the form of active play) should be a natural part of the child's daily life ? a habit as common as brushing teeth.
Said Dr. Samuel Abbate, at a childhood obesity conference sponsored by the North Dakota Department of Health: "The consequences of denying the body exercise are just as severe as depriving it of food, water, or oxygen; it just takes longer to see the consequences."
Rae Pica is a children's physical activity specialist and the author of Your Active Child: How to Boost Physical, Emotional, and Cognitive Development through Age-Appropriate Activity (McGraw-Hill, 2003). Rae speaks to parent and education groups throughout North America. You can visit her and read more articles at http://www.movingandlearning.com.