Populations worldwide are becoming more corpulent. The levels of overweight and obesity in many low- to middle-income countries such as Mexico, Egypt, and South Africa rival that of the country used as the benchmark for this problem, the USA. Moreover, the rates of increase in obesity in these countries are double to quadruple those in the USA. In this article, Barry Popkin reports on the impact of important shifts in nutritional patterns and the trend towards inactivity.