The candidate's overarching goal is to develop diet interventions to address pediatric obesity that are specifically tailored to an individual's metabolic profile. Her specific interest is the interaction of diet quality with the changes in insulin secretion and action that occur during the pubertal transition. To achieve this objective, the candidate has identified, as a mentoring team, experts in reproductive/metabolic endocrinology and statistical genetics, both of whom have a proven track record of successful research, collaboration, and productivity. The mentored training secured by this award will involve coursework in genetics, metabolism, and endocrinology; training in laboratory skills; and completion of the candidate's funded pilot study involving a diet intervention in African American peripubertal girls. As the coursework and training progress, there is a planned transition to developing a research protocol, and training in the skills needed for its conduct. Emphasis also will be on cultivation of funding opportunities for future projects. The candidate's proposed research project builds on her previous and ongoing research in adults and children, which has identified dietary factors that affect insulin secretion and obesity. Specifically, the proposed study aims to determine if a diet specialized for the unique metabolic characteristics of peripubertal girls (i.e. low insulin sensitivity/high insulin secretion) is more effective than a standard diet in, 1) decreasing insulin secretion and increasing insulin sensitivity; 2) achieving greater weight loss and weight-loss maintenance; and 3) decreasing estradiol concentration, which may affect fat deposition during the pubertal transition. The specialized diet emphasizes modification of diet quality, particularly carbohydrate quantity/quality. The ultimate goal of this project, and related future research, is to develop dietary guidelines for overweight adolescents tailored to their individual metabolic profile. Effective modification of the diet to improve metabolic and obesity-related outcomes will reduce reliance on pharmacological agents. The outstanding scientific environment afforded by the DAB will allow for continued professional growth and development. Further, th K99 will be the perfect opportunity for the to transition into an independent investigator in the area of pediatric obesity.