Design of a randomized trial testing a multi-level weight-control intervention to reduce obesity and related health conditions in low-income workers.

Weight-control is a major public health focus for preventing multiple obesity-related health conditions. While clinic-based intensive lifestyle interventions are successful, low-socioeconomic-status (SES) populations, which have a higher burden of obesity, are difficult to reach; thus, the workplace offers a useful setting to target low-SES workers. The current paper presents the design of a study testing a workplace intervention aimed at low-SES employees. Partnering with a large healthcare system and affiliated university, this project will test an innovative multi-level intervention ("Working for You") adapted from existing group- and individual-level intervention models to promote healthy weight among low-wage workers. The individual-level component is an interactive obesity treatment approach (iOTA) program that involves assessment of behavior risks, collaborative goal-setting with a health coach, and interactive SMS text-messages for ongoing support and self-monitoring. This mHealth intervention is embedded in the group-level component, a workplace participatory program that involves worker teams engaged in the design and implementation of interventions to change their workplace environments. These nested interventions are being tested in a group-randomized trial among 22 work groups (~1000 total workers, ~300 workers with obesity). The primary outcome will be program effects on weight at 2-year follow-up, compared to control, and the secondary outcomes will be effects on diet and physical activity; iOTA adherence, process measures, and work environment/support will also be examined. This pragmatic clinical trial will test scalable interventions that can be translated to other work settings to reduce obesity and related health risks among low-SES workers. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT02934113.