Changes in Circulating Satiety Hormones in Obese Children: A Randomized Controlled Physical Activity-Based Intervention Study

The aims of this study are to examine in children: (i) obesity-related alterations in satiety factors such as leptin, ghrelin, and obestatin; (ii) the link between satiety factors and cardiometabolic risk factors; and (iii) the impact of a physical activity-based lifestyle intervention on the levels of these satiety factors in the obese. We studied a total of 21 adolescents (BMI percentile, 99.0 +/- 0.6 for 15 obese and 56.2 +/- 1.1 for 6 lean). The obese subjects underwent a 3-month randomized controlled physical activity-based lifestyle intervention. Leptin, soluble leptin receptor (sOB-R), ghrelin, and obestatin levels were determined as the primary outcome measures. Other markers of cardiometabolic disease such as inflammation and insulin resistance were also determined. Body composition was measured by dual-energy X-ray absorptiometry. The concentrations of ghrelin, obestatin, and sOB-R were significantly lower in the obese children compared to the lean controls, whereas that of leptin was higher (all P < 0.05). Although intervention led to a net increase in obestatin (P < 0.01) and no change in ghrelin levels, the balance between ghrelin and obestatin (ratio of ghrelin to obestatin, G/O) decreased (P < 0.02). Intervention reduced leptin and increased sOB-R (P < 0.01 for both). Significant associations between satiety factors and other cardiometabolic risk factors were also observed. Taken together, alterations in the levels of satiety factors are evident early in the clinical course of obesity, but physical activity-based lifestyle intervention either prevented their continued increase or normalized their levels. These beneficial effects appear to aid in the maintenance of body weight and reduction in cardiovascular risk.