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How Diet and Activity Affect Weight in Children

Researchers created a mathematical model that simulates how weight and body fat in children respond to changes in diet and physical activity. The model may offer new insights for addressing childhood obesity.

More than one-third of children and adolescents in the United States are overweight or obese. Excess weight at an early age can lead to lifelong health problems such as type 2 diabetes and high blood pressure.

Promoting weight loss in children, however, can be complicated. Because their bodies are growing, some weight gain is normal. Excess weight occurs when calories eaten are greater than the energy the body needs. However, growing evidence shows that the body’s metabolism can change as you alter your diet or exercise habits. Keeping track of these metabolic changes can be difficult, especially during childhood growth.

A research team led by Dr. Kevin Hall of NIH’s National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) previously developed a mathematical model that simulates weight changes in adults. In their new study, they set out to adapt the model to capture the unique characteristics of child metabolism. Such a model could be used to predict how well different weight loss approaches might work in children of different ages.

The researchers used clinical data from 5- to 18-year-olds to create the model. To test its effectiveness, the team compared model predictions to actual changes in children that were measured in other clinical studies. As reported online on July 30, 2013, in Lancet Diabetes and Endocrinology, the researchers developed a model that accurately predicted observed changes in body fat and weight.

Using the model, the scientists were able to identify major differences between obese adults and children. For example, a child under age 10 requires more than twice as many calories as an adult to gain excess weight.

The model suggests that the adolescent growth spurts of obese boys might be harnessed to “outgrow” obesity. By successfully maintaining weight from ages 11 to 16, simulated boys lost their excess body fat. However, the effect wasn’t as pronounced in simulated obese girls, suggesting that obese girls would likely need to lose weight to normalize their body fat during this period.

“Obese children are much more likely to become obese adults, which makes achieving or maintaining a healthy weight early in life vitally important,” says NIDDK Director Dr. Griffin P. Rodgers. “This study suggests that we may need to approach weight management and obesity prevention differently in youth than in adults.”

“Our model, which takes growth into consideration, helps quantify realistic goals for weight management in children and adolescents,” Hall says.

Looking forward, researchers are exploring options to develop a user-friendly online tool for health professionals and others. Parents should work with a health care provider before beginning any weight-loss program for an overweight or obese child.