Institute for Health Metrics and Evaluation (IHME) has estimated trends in obesity and overweight prevalence worldwide and by country for the years 1980 to 2013. Data were derived from surveys, reports, and published studies that included data for height and weight, both through physical measurements and self-reports. The results are released in May 2014. Body mass index (BMI) is a weight-to-height ratio. Overweight persons have a BMI greater than or equal to 25 and less than 30. Obese persons have a BMI greater than or equal to 30.