Fighting the food fight: why and how do we get kids caring about diet and exercise?

Roughly two-thirds of the U.S. population is now overweight or obese. According to a 2004 public health survey for Obesity Reviews, nine million youths in the United States are overweight. And 30% of Americans 12 to 19 years old are currently overweight.

Of the seven major cardiac risk factors established by the well-known Framingham study, four have causal connections to overweight: hypertension, high LDL or "bad" cholesterol, diabetes, and obesity itself (the others are heredity, age, and smoking). In fact, in 2003, diabetes was elevated from a risk factor to a heart-disease equivalent. Most of us are well aware that exercise lowers cholesterol and blood pressure and improves cardiovascular health, but what else have we learned about its importance, and how can we ensure that our children will incorporate it, along with healthy eating habits, into their ever-hectic lives?

The stress reducer

Regular exercise reduces stress. When the once frequently needed fight-or-flight response inappropriately triggers to deal with modern stress, it can turn against the body over the long haul. The increased heart rate, blood pressure, blood sugar levels, muscle tension, anger, and anxiety are designed to quickly dissipate after an immediate physical threat is over. These days, we are most often faced with stress such as workplace or marital tensions that never entirely resolve. The hormones causing these stress responses can lead to heart disease, hypertension, colitis, suppressed immunity, and depression. Exercise allows a release of this physical stress, and counteracts the anxiety that adrenaline and cortisol cause when they enter the bloodstream for prolonged periods. It also stimulates the release of serotonin, which activates the brain's "happy centers."

For better immunity

Moderate levels of exercise have repeatedly been shown to increase white blood cell count. Children above all others can benefit from this improved immunity. Not only are they exposed to more colds and infections due to the close quarters of schools and day care centers, but a child's nasal secretions actually contain higher concentrations of cold virus than an adult's.

Improved sleep

Regular exercise has long been prescribed as one of the cornerstones of good sleep hygiene. It's not hard to see why. Sleep serves an energy conservation function, regulates body temperature downward, and allows for body tissue restitution; nothing elicits greater energy depletion, body temperature elevation, or tissue breakdown in humans than exercise.

The cascade effect

Even attempting to lose weight and failing lowers your mortality rate. In a study of over 6,000 overweight and obese subjects, the Centers for Disease Control and Prevention found a 19% decrease in mortality over nine years in unsuccessful weight-loss candidates, as compared to no change in mortality for those not trying to lose weight. The researchers suspect the attempts at weight loss engaged the subjects in other healthy behaviors that lowered their mortality. This is an important insight in the fight against youth overweight: Exercise and healthy eating can have a cascade effect, promoting other healthy behaviors, like avoiding smoking.

Bone health

In the summer of 2004, the Iowa Bone Development Study published data on some 467 children (mean age five years) that indicated that even everyday levels of physical activity can make a significant impact on the bone strength of very young children, whether they are physically fit or not. The skeleton is most sensitive to mechanical loading during early childhood, and regular load-bearing exercise is essential at this stage. Exercise recommendations are not always realistic in the day-to-day lives of children. But the study found that in young children, bones structurally remodel (and therefore strengthen) with almost any daily activity, not just with targeted bone loading activities or vigorous amounts of activity.

The positive effects are myriad; so what do we do?

Community is key

A recent study from the RAND corporation finds that adolescents from close-knit neighborhoods are less likely to become obese. The researchers define close-knit communities as those in which neighbors get along and are helpful to other families, and adults serve as role models for children and teenagers. Such "collective efficacy" was found to be more important in predicting childhood obesity in the study's neighborhoods than both ethnic/racial make-up and resident income level.

In the home, at school

For better or worse, children are creatures of habit. Simply by limiting your child's television time to less than two hours a day, you can counterstrike against trends toward overweight. The link between TV and adiposity (fatness) is well documented, and trifold: If you're watching TV, you're inactive--kids burn less calories watching TV than doing just about anything else; if you're watching TV, you're being bombarded with food messages; and if you're watching TV, you're likely to snack.

Look for ways to enjoy physical activity as a family. Play soccer, run races, invent games, go on hikes. Sledding, skating, bicycling, and swimming are all great family activities, with the operative word being activities.

One randomized trial of 24 public middle schools designed a physical education intervention to increase student physical activity during existing PE classes. A total of 25,000 students in Southern California--45% of whom were non-white, with 39% participating in free or low-cost meal plans--were involved in the two-year study. The results border on shocking: By training the PE teachers for three 3-hour sessions in the first year (and just two in year two) to raise need awareness for more active PE curricula, the teachers raised student activity levels by 18% without increasing the frequency or duration of PE lessons. No new teachers were hired; the intervention staff simply educated existing PE staff. As effective strategies the study cited a newfound emphasis on actually playing, as opposed to, say, learning an in-depth history of, a given sport; and calling the roll and distributing equipment while students warmed up.

Eating well

According to a two-decade study of over 16,000 Americans ages 12 to 29, American teens are obtaining less of their energy intake at home, and evermore at fast food restaurants. The study also found, not surprisingly, significant increases in pizza, cheeseburger, and salty snack consumption. Last year, the average American consumed approximately 140 pounds of sugar.

This is 50% more than the Germans or the French, and nine times as much as the Chinese. Sugar rots teeth and contributes to erratic behavior, adiposity, and diabetes. So how do we handle our children's cravings for it?

Do offer a variety of healthful foods in place of sugar. Dieticians often say half the weight-loss battle is won simply by keeping the right foods available for when hunger strikes. It's good to limit empty-calorie snacks, and to set a good example. But keep in mind admonishing children to eat less can backfire. Food restriction can create an unhealthy focus on dieting and body image.

Always look at the trans fat content in the foods you buy. (The FDA move mandating that food manufacturers list this information on food labels may well encourage manufacturers to abandon trans fat altogether.) The link between trans fat and coronary heart disease is well established. As the ongoing Harvard Nurses Health Study reports, "The replacement of 2% of energy from trans fats with energy from unhydrogenated, unsaturated fats would reduce [heart attack] risk by 53%." Trans fats are often found in vegetable shortening, solid margarines, crackers, candies, baked goods, and fried foods. Always choose unsaturated fats, and avoid anything hydrogenated.

(Social Sci. & Med., 2006, Vol. 62, No. 3, pp. 769-778; Clin. Sports Med., 2005, Vol. 24, No. 2, pp. 355-365; Med. Sci. Sports & Exerc., 2005, Vol. 37, No. 12, pp. 2032-2037; 2004, Vol. 36, No. 8, pp. 1382-1388; 2004, Vol. 36, No. 7, pp. 1124-1131; Harvard Women's Health Watch, "Reducing the Burden of Stress," 2003, Vol. 10, No. 1; Health After 50, 2004, Vol. 16, No. 10, pp. 4-5; Preventive Med., 2002, Vol. 35, No. 2, pp. 107-113; www.fitnessmanagement.com)