Obesity is an epidemic in the U.S., with a third of adults obese. Obesity exerts enormous impact on the nation's health and economy largely through its effect on coronary heart disease (CHD) risk factors: 3 in 4 obese Americans have at least one CHD risk factor reversible through weight loss. Working within acute care-centered systems, most clinicians are unsuccessful in helping their patients lose weight or prevent weight gain. A promising and well-studied approach is integrated care delivered by nurse and dietitian case managers (CMs). Nonetheless, clinical prevention services (including CM) may be less effective if provided in isolation from patients' living environments that so often reinforce caloric excess and physical inactivity. This application leverages our extensive expertise in developing and disseminating effective CM programs (Heart to Heart, R01 HL070781). We will implement an obesity-focused CM program that focuses on established behavioral weight loss and maintenance strategies and evidence-based CHD prevention targets. We also will test the additional benefit of structured environmental support (ES) carried out by community health workers that will bridge the gap between the clinic and patients' homes and neighborhood. Our Specific Aims are to: 1) Implement innovative, primary care-based CM and CM+ES interventions in a randomized clinical trial. We will conduct this trial at a San Mateo Medical Center (SMMC) health center serving an ethnically diverse, low-income population. We will randomize 200 obese adults with at least one obesity-related CHD risk factor over 18 months to usual primary care (40 patients), CM alone (80), or CM+ES (80). Intervention patients in will receive an intensive weight loss and CHD risk intervention for 12 months, followed by 12 months of maintenance intervention. 2) Determine the effectiveness and cost-effectiveness of the CM and CM+ES for improving BMI and CHD risk factors, relative to usual care and each other. Our PRIMARY HYPOTHESIS is that patients managed through CM+ES will experience greater reductions in BMI over 24- months than those in CM. 3) Transition the favored intervention to a sustainable program, supported by the County, as well as explore opportunities for broader dissemination to other County and non-County systems. A business case for dissemination based on our findings will be critical in seeking this investment. This project will develop and test two novel models of care design to support sustained weight loss. Given the failure of current mechanisms to address obesity and elevated CHD risk, these models have the potential to provide a blueprint for primary care-based obesity services that can reduce this nation's burden of obesity, especially for low-income populations. Physician-based primary care has thus far failed to address the obesity epidemic. In a randomized clinical trial of 200 obese patients with heart disease risk factors, we will evaluate the impact of nurse and dietitian case management on weight loss and weight maintenance, as an adjunct to physician care. In addition, we will test the incremental benefit of an environmental support strategy using community health workers to help patients navigate their home and neighborhood environments to achieve weight loss. The innovative intervention model developed and evaluated in this project has the potential to provide a blueprint for successful primary care-based obesity services. PUBLIC HEALTH RELEVANCE: Physician-based primary care has thus far failed to address the obesity epidemic. In a randomized clinical trial of 200 obese patients with heart disease risk factors, we will evaluate the impact of nurse and dietitian case management on weight loss and weight maintenance, as an adjunct to physician care. In addition, we will test the incremental benefit of an environmental support strategy using community health workers to help patients navigate their home and neighborhood environments to achieve weight loss. The innovative intervention model developed and evaluated in this project has the potential to provide a blueprint for successful primary care-based obesity services.