Childhood obesity is a significant, worldwide, public health problem. Coinciding with the increasing prevalence of obesity in youth, Type 2 diabetes has emerged as a critical health condition in this population. In the U.S. alone, approximately 215,000 U.S. youth under the age of 20 were diagnosed with diabetes, with the majority of 10-19 years old diagnosed with Type 2 diabetes. Additionally, the exact number of youth that may have Type 2 diabetes yet remain undiagnosed is unknown. Increasing physical activity to encourage weight loss among youth may reduce the incidence of Type 2 diabetes in youth; however, several recent studies reported positive associations between physical activity and components of Type 2 diabetes without weight loss in youth. These findings support previous studies in adults which observed physical activity-induced improvements in insulin dynamics without changes in body fat. The purpose of this review was to identify studies which examined the effect of physical activity without dietary intervention on markers of insulin resistance in overweight and obese youth. These studies provide strong evidence that physical activity alone, without dietary intervention, can have a positive, significant impact on insulin resistance risk and potentially prevent the development of type 2 diabetes in overweight and obese youth. The studies reviewed provide support for future interventions to shift the focus from reducing obesity to increasing physical activity for the prevention of type 2 diabetes in obese youth.
Keywords: Insulin resistance, Lean body mass, Obese youth, Physical activity, Resistance training, Type 2 diabetes, Hyperglycemia, Hyperinsulinemia, Anthropometric assessment, Frequently Sampled Intravenous Glucose Tolerance Test (FSIVGTT), Bioelectric Impedance Analysis (BIA), Dual energy x-ray absorptiometry (DEXA)