The purpose of this study is to test a workplace intervention program targeted at low SES workers. Working in partnership with BJC HealthCare, we will test an innovative multi-level intervention that includes an interactive obesity treatment program (iOTA) using SMS text messaging. The iOTA intervention will be embedded in a newly described Healthy Workplace Participatory Program, which incorporates employee participation in decision making to produce changes in the workplace environment that are acceptable, effective, and sustainable. These nested interventions will be tested a large delayed-start group-randomized trial. This study will rigorously test readily scalable interventions that can be translated to other work settings to reduce obesity and diabetes risk among low SES workers, a group at high risk for these disorders. This pragmatic clinical trial will advance the long-term goal of enabling employers and employees to reduce obesity and obesity-associated illnesses including diabetes.