Effect of a short-term diet and exercise intervention on metabolic syndrome in overweight children

Abstract

Overweight and the metabolic syndrome are increasing radically in children. The present study was designed to examine the effects of lifestyle modification in 16 children who were placed on a high-fiber, low-fat diet in a 2-week residential program where food was provided ad libitum and daily aerobic exercise was performed. In each subject, pre- and postintervention fasting blood was drawn. Insulin (27.2 ± 3.5 vs 18.3 ± 1.7 μU/mL, P < .01), homeostasis model assessment for insulin resistance (5.79 ± 0.81 vs 4.13 ± 0.38, P < .05), and body weight (92.0 ± 7.0 vs 88.0 ± 6.8 kg, P < .01) were reduced significantly. Total cholesterol (165 ± 7.8 vs 127 ± 7.4 mg/dL, P < .01), low-density lipoprotein (94.1 ± 8.2 vs 68.5 ± 6.7 mg/dL, P < .01), triglycerides (146 ± 16.2 vs 88.1 ± 8.1 mg/dL, P < .01), and total cholesterol–high-density lipoprotein (4.16 ± 0.30 vs 3.34 ± 0.30, P < .01) and low-density lipoprotein–high-density lipoprotein ratios (2.41 ± 0.3 vs 1.86 ± 0.2, P < .01) were reduced, with no change in high-density lipoprotein observed (42.3 ± 2.4 vs 40.8 ± 3.0 mg/dL). Systolic blood pressure (130 ± 3.1 vs 117 ± 1.8 mm Hg, P < .001) and diastolic blood pressure (74.3 ± 3.0 vs 67.2 ± 2.3 mm Hg, P = .01) also decreased. Most notably, before the intervention, 7 of the 16 subjects were classified with metabolic syndrome. After the 2-week intervention, despite remaining overweight, reversal of metabolic syndrome was noted in all 7 subjects. All of these changes occurred despite only modest improvements in the percentage of body fat (37.5% ± 1.1% vs 36.4% ± 1.2%, P < .01) and body mass index (33.2 ± 1.9 vs 31.8 ± 1.9 kg/m², P < .01). These results indicate that a short-term rigorous diet and exercise regimen can reverse metabolic syndrome, even in youth without documented atherosclerosis.

Introduction

Obesity is a significant public health issue in the United States [1], [2], and children and adolescents have not eluded this emerging epidemic. In 2000, more than 15% of children and adolescents in the United States aged 6 to 19 years were classified as overweight (body mass index [BMI] >95th percentile), more than triple the percentage recorded 30 years earlier [3]. In addition, the Centers for Disease Control and Prevention (CDC) reported that 62% of children 9 to 13 years of age do not participate in any organized physical activity during nonschool hours [4]. Consequently, today's overweight children and adolescents are potentially setting the stage for heightened risk of cardiovascular disease, type 2 diabetes mellitus, cancer, osteoarthritis, and premature all-cause mortality later in life [5].

Obesity is highly correlated with a constellation of disorders including dyslipidemia, insulin resistance, and hypertension—hallmarks of the metabolic syndrome and risk factors for cardiovascular disease. Diagnosis of this syndrome is indicated when 3 or more of the following risk factors coexist: central obesity, elevated blood pressure, elevated fasting glucose or insulin resistance/hyperinsulinemia, elevated triglycerides (TG), and reduced high-density lipoprotein (HDL). According to the Third National Health and Nutrition Examination Survey, between 1988 and 1994, it was estimated that the metabolic syndrome was present in more than 6% of overweight adolescents and more than 25% of obese adolescents [6]. Accumulating evidence indicates that the prevalence of these metabolic abnormalities is increasing among the youth of America and other industrialized countries [7], [8], [9]. The ramifications are significant, given that overweight children tend to remain overweight or become obese in adulthood [10], and predicts that the percentage of adults at risk for the metabolic syndrome and cardiovascular disease will continue to climb if current overweight trends continue [11].

Although it is clear that overweight and obesity prevalence is increasing in children and adolescents in westernized societies, there are few studies examining combined physical activity and diet interventions in this subset of the population. The goal of this study was to investigate the effects of short-term daily physical activity and a low-fat, high-fiber diet on the metabolic syndrome and related coronary artery disease (CAD) risk factors in overweight youth.