Following an introduction in which readers are introduced to the concepts of body mass index (BMI), the definition of obesity and the physiology of glucose metabolism, this chapter discusses the following requirements for dealing with a changing work population: job demands must match the work capacity of employees, work should provide the optimal level of physical activity, shift systems must minimize disruption of sleep, at least 6 h of uninterrupted sleep every 24 h and 2 additional hours of rest, and facilities for healthy eating and exercise should be provided. Current problems of ill health in the workforce are described, particularly insulin resistance, Type II diabetes, and the problem of inactivity in the context of “fitness for work.” There is also a discussion of sleep, circadian rhythms, shift work, and jet lag. Guidance is provided to avoid designing an “obesogenic” workplace. A checklist for monitoring habitual activity is given and the work ability index (WAI) is described. Finally, the effectiveness of occupational fitness and work-hardening programs is discussed together with future trends.