Commercial truck drivers have overweight and obesity rates that may be 20% higher than the general population. Obesity has established mortality and disease consequences, including heart disease, diabetes, and sleep apnea. Driver health is also an important safety hazard because obesity and sleep apnea increase the risk of crashes. Drivers experience multiple roadblocks to health, including an isolating job structure that restricts physical activity and dietary choices. Despite the growing health crisis, there is a lack of effective weight loss and health promotion interventions for truck drivers. We therefore developed an intervention that is integrated with the job structure and modern technologies of truck driving. The intervention is a 6-month weight loss competition supported with computer based training, behavioral self-monitoring, and motivational interviewing. The study is a cluster randomized trial where worksites (terminals) will be randomized to intervention and control conditions. We will collect measures from drivers at baseline (month 0), post-intervention (month 6), and one-year follow-up (month 18). The project will take place over five years and accomplish three specific aims:

1. Determine intervention efficacy for producing changes in diet, exercise, and body weight. Previous weight loss interventions for truck drivers have been minimally effective, and there is a need to evaluate new approaches with randomized, controlled designs. Therefore, we will randomize matched pairs of worksites (terminals) to intervention and control conditions. Drivers at intervention terminals will complete intervention activities over a 6-month period. Drivers at control terminals will receive no treatment during the same time period. Primary outcomes will be changes in body weight, fruit and vegetable consumption, high-saturated fat and high-sugar food consumption, and physical activity.
2. Determine whether baseline social support and stress moderate intervention efficacy. Although social support and stress have established effects on weight loss with other populations, we know little about the role of social support and stress during interventions for truck drivers. Therefore, we will measure social support and stress in home and work environments at each measurement time point. After the intervention, and again at one-year follow-up, we will test whether social support and stress factors moderated subsequent behavior change and weight loss.
3. Measure the integrity of each intervention component and model how the intervention worked. We are evaluating a new multi-component intervention with an understudied population. In order to understand how the intervention worked and guide future research, we will measure fidelity and participation in each intervention component and use mediation analyses to determine how the different components affected study outcomes. Analyses will provide an explicit check of the intervention's theoretical underpinnings and assess whether proposed change processes were achieved.

Accomplishing our aims will significantly advance weight loss and health promotion knowledge to the benefit of over 3 million truck drivers in the US, and potentially generalize to 15 million additional workers who spend substantial time alone or traveling for work.