The prevalence of overweight and obesity is increasing worldwide.1 Epidemiologic studies have identified high body-mass index (BMI, the weight in kilograms divided by the square of the height in meters) as a risk factor for an expanding set of chronic diseases, including cardiovascular disease,2,3 diabetes mellitus, chronic kidney disease,2 many cancers,4 and an array of musculoskeletal disorders.5,6 As the global health community works to develop treatments and prevention policies to address obesity, timely information about levels of high BMI and health effects at the population level is