PROJECT SUMMARY/ABSTRACT Weight loss maintenance remains the Achilles' heel of obesity management. Extended intervention contact reduces weight regain. However, continued counseling in practice is rare. Digital health interventions can address barriers to providing in-person maintenance counseling. Our long-term goal is to develop more effective weight loss maintenance strategies that are accessible, patient-centered, and tailored to meet individuals' needs. To accomplish this goal, the proposed trial will examine whether, after 16 weeks of initial weight loss, a stepped-care, digital health intervention improves the maintenance of a >5% weight loss. Phase I lifestyle phase, (UC); (STEP). SELF is a non-randomized, 16-week, weight-loss phase during which all participants wil receive the same group intervention designed to induce a > 5% weight l oss. In Phase II, a 52-week weight-loss maintenance 180 adults with obesity who have lost >5% will be randomized to one of three interventions: usual care daily self-monitoring of weight, diet, and physical activity with digital tools (SELF); or The UC group will receive monthly, emailed weight loss maintenance education. Participants in the group will have access to a digital health intervention that uses: l stepped care daily remote monitoring of weight, physical activity, and calorie intake; and automated, personalized text-messaging to adherence. 13 additionally (Step percentage weeks, transition encourage behaviora begin with access to the digital health program (Step 1). Participants who, after the first weeks, have not maintained their 5% weight loss or have regained 2 percentage points of their weight, will receive monthly visits with a counselor to promote behavioral adherence and address barriers 2). Participants who, at 26 weeks, have not maintained a > 5% weight loss or have regained 2 points with Step 2 will transition to twice-monthly counseling (Step 3). Participants who, at 39 still have not maintained a > 5% weight l oss or have regained 2 percentage points with Step 3 will to a partial meal replacement plan for the last 13 weeks (Step 4). l STEP will Our primary aim is to determine if SELF and STEP result in better maintenance of weight loss compared to UC. Our secondary aims are to examine differences in self-weighing frequency, eating behaviors, and physical activity, and examine if STEP, relative to SELF, produces greater improvements in weight, self-weighing frequency, eating behaviors, and physical activity. each We will also conduct an economic analysis to evaluate the incremental cost effectiveness of intervention per unit decrease in weight (kg).The expected outcome of the study is to demonstrate the efficacy of a digital health intervention for weight loss maintenance, providing a solution to many challenges that interfere with successful delivery of obesity treatment. We also expect to show the efficacy of a stepped care model for weight loss maintenance, providing a individuals...