Obesity has become a global epidemic. According to the World Health Organization, at least 400 million adults are obese. They project that by the year 2015 some 2.3 billion adults will be overweight, and many of those adults are living in the developing world, in countries where malnutrition was once rampant.

Barry Popkin has studied the spread of obesity across six continents. He's a Professor of Global Nutrition at the University of North Carolina, Chapel Hill and the author of  The World is Fat The Fads, Trends, Policies and Products that are Fattening the Human Race.