Why do some overweight children remain overweight, whereas others do not?

OBJECTIVE To study the dynamics of childhood overweight and the influence of dietary intake on tracking of overweight. DESIGN AND SETTING A follow-up study conducted in China. SUBJECTS Ninety-five overweight children, 6-13 years old, identified from 1455 children at baseline, were followed over a 2-year period. METHODS Data on anthropometry and 3-day dietary intake were collected at baseline and during follow-up. Overweight was defined using the International Obesity Task Force reference of body mass index (BMI)-for-age. Differences between groups were tested using analysis of variance and Cochran-Mantel-Haenszel tests. RESULTS Of the 95 overweight children, 36.8% remained overweight 2 years later ('tracking group'). Urban boys were three times more likely than rural boys to remain overweight (63.2% vs. 21.9%). At baseline, the tracking group had higher BMI, body weight and fat intake (% of energy), and lower carbohydrate intake (% of energy), than the non-tracking group (who shifted from overweight to not overweight); they were more likely to have a high-fat or high-meat diet, but less likely to have a diet high in carbohydrate or vegetables and fruit. During the follow-up, the tracking group increased fat intake and reduced carbohydrate intake while the non-tracking group did not; and they also grew slower in height but faster in weight. Tracking of overweight seemed to be related to tracking of high-meat (relative risk (RR) 2.4, 95% confidence interval (CI) 1.0-5.6, P < 0.05) and high-fat (RR 1.5, 95% CI 0.9-2.5, P < 0.1) diets. CONCLUSION Considerable changes in children's overweight status during childhood and adolescence were observed in China, a transitional society. Dietary patterns, particularly dietary composition, seemed to influence the tracking patterns of overweight.