In the United States, obesity is a major public health problem, with about two of every three Americans overweight or obese. Obesity is associated with heart disease, diabetes, high blood pressure, osteoarthritis, depression and other chronic health conditions. Employers pay a large share of the associated health and productivity costs. In response, many employers focus on weight management as a core focus of company-sponsored health improvement programs. Worksite interventions to address the problem of overweight and obesity are commonly designed to improve personal lifestyle factors that directly contribute to energy imbalance. Program components typically incorporate education, skill-building, and policy and environmental supports to improve diet and physical activity levels of employees. Effectiveness depends on high levels of program intensity and employee participation, and the weight loss achieved is often modest and difficult to sustain. There is little or no focus on the physical and psychosocial conditions of work, even though these may be important drivers of weight gain.