Images of a Healthy Worksite: A Group-Randomized Trial for Worksite Weight Gain Prevention With Employee Participation in Intervention Design

摘要

Objectives. We assessed the effects of a worksite multiple-component intervention addressing diet and physical activity on employees’ mean body mass index (BMI) and the percentage of employees who were overweight or obese. Methods. This group-randomized trial (n?=?3799) was conducted at 10 worksites in the northeastern United States. Worksites were paired and allocated into intervention and control conditions. Within- and between-groups changes in mean BMIs and in the percentage of overweight or obese employees were examined in a volunteer sample. Results. Within-group mean BMIs decreased by 0.54 kilograms per meter squared ( P?= .02) and 0.12 kilograms per meter squared ( P?= .73) at the intervention and control worksites, respectively, resulting in a difference in differences (DID) decrease of 0.42 kilograms per meter squared ( P?= .33). The within-group percentage of overweight or obese employees decreased by 3.7% ( P?= .07) at the intervention worksites and increased by 4.9% ( P?= .1) at the control worksites, resulting in a DID decline of 8.6% ( P?= .02). Conclusions. Our findings support a worksite population strategy that might eventually reduce the prevalence of overweight and obesity by minimizing environmental exposures to calorically dense foods and increasing exposures to opportunities for energy expenditure within worksite settings. Sixty-eight percent of adults residing in the United States are overweight or obese, 1 and these conditions affect more than 1.4 billion adults worldwide. 2 Traditional obesity control strategies, which have focused on changing diet and physical activity (PA) behaviors, provide significant individual benefits 3 but are considered insufficient to reduce population disease burdens, 4,5 for which broad, population-based approaches are needed. 6 In addition to individual biology and behaviors, the physical, social, and cultural environment appears to contribute to the upward trend in population estimates of overweight and obesity 7,8 by facilitating high-energy, low-nutrient diets and reducing the need to be physically active to perform activities of daily life. 9 Worksites are feasible self-contained environments with established communication systems in which interventions manipulating the food and PA environment and the social marketing of lifestyle changes can be implemented. Given that 58.4% of the US population aged 16 years or older is employed, 10 worksite interventions have the potential to reach large number of adults 11 and can foster the participation of employees in project development and sustainability. 12–14 Moreover, participatory worksite interventions address workers’ needs, priorities, and interests and allow strategies to be adapted to the realities of individual sites. 13 There is also a business case for weight control programs. In comparison with their nonobese counterparts, overweight and obese employees have higher absenteeism rates, have more work limitations, and are less productive. 15–18 With these issues in mind, the National Heart, Lung, and Blood Institute developed the Obesity Prevention in the Worksite initiative, a population-based approach to promoting behavioral change through environmental interventions that address prevention and control of weight gain. 19 Prior to this initiative, worksite trials were either limited scope interventions, targeting a few aspects of the food or PA environment, 9,20–23 or broader scope efforts simultaneously targeting risk factors for cardiovascular disease and cancer (e.g., smoking, diet). 24–28 In addition, few studies addressed environmental influences related to excessive weight gain. Here we report the results of Images of a Healthy Worksite, one of the studies that is part of the Obesity Prevention in the Worksite initiative; this comprehensive nutrition and PA intervention was designed to promote healthy lifestyles and to stop the shift to the right of the population body mass index (BMI) curve. In this study, worksites were designated to receive an environmental intervention, and employees participated in intervention design. We hypothesized that mean BMIs among employees at the intervention worksites and the percentages of employees who were overweight or obese would not increase over a 2-year period or would increase less than at control worksites.