Think AHEAD (A Healthy Eating And Drinking) Study

This is a 6-month randomized controlled trial. After the initial baseline screening and assessments, 60 overweight adolescents will be randomly assigned (30 subjects per group) to a standard weight-reducing diet with the advice to consume 8 cups of water per day (experimental group) or the same standard weight-reducing diet without additional advice (control group). The interventions will consist of nutrition education and behavioral counseling by a registered dietitian, during individual sessions and telephone calls. Mobile text messaging will be used to reinforce information presented at the individual sessions and thereby foster adherence to dietary advice. Diet prescriptions will differ only in regard to the specificity of recommendations regarding water consumption and physical activity recommendations will not differ between groups. The frequency and content of text messages will be consistent between the experimental and control groups, with the exception that the experimental group will receive an additional phrase with each message to encourage the "8 x8" water recommendation. A registered dietitian will communicate with each participant one time per month, either during an individual session or by telephone. Individual sessions will include nutrition classes, taste testing, hands-on activities, and opportunities for questions and answers. Text messages will be sent on a daily basis. Study outcomes will be assessed at baseline and at regular intervals throughout the 6 months of the study. ANALYSIS PLAN: The blinding of the randomization will be broken on or after July 28, 2014 and the data will be analyzed according to the following plan. All analyses will follow the intention-to-treat principle, attributing each subject to his or her assigned diet regardless of compliance. Baseline characteristics will be compared between the diet groups using the Fisher exact test for categorical variables and t-test for continuous variables. The 6-month change from baseline in the primary and secondary outcomes will be compared between groups using a general linear model, adjusting for baseline covariates that are potentially correlated with the outcome. These include demographics, socioeconomic status, anthropometrics, physical activity, and beverage consumption. We will further test covariates for potential interaction, i.e., differential effect on outcome in the two trial arms. The null hypothesis is that the 6-month change from baseline will not differ between diet groups.