The data on weights and heights are collected either through health interview surveys, which ask persons to report their own height and weight, or through health examinations that record objective information on people’s height and weight. The latter method provides more reliable information and in general higher estimates of overweight/obesity than do self-reports. Japan leads a large group of countries (including more than half of the OECD countries) in which total life expectancy at birth currently exceeds 80 years. A second group, including the United States, China, Brazil and a number of central and eastern European countries, have a life expectancy of between 70 and 80 years.