let's check with nadia bilchik. yes. >> what did they find? >> the london school of hygiene came up with the entire mass of the world, if they weighed all the people in the world would come to 633 billion pounds. that is about 360 million tons. they say 16.5 tons of that is due to overweight. >> we pointed out americans because we said we know obesity is a growing problem in the country. the u.s. is responsible for nearly one-third of the world's excess weight. >> isn't that extraordinary? north america is 6% of the world's population, but 35% of the world's weight. an average person is around 137 pounds, supposedly. in america, the average is 178 pounds. >> wow. it's a lot more. >> it is quite a bit more. the ramifications, they are saying people that are overweight use more energy. it's not only the effect they have on their own organs and body, the study is the effect it has on the environment and the earth. >> how so? literally using more energy. >> not only in terms of nutrition, but resting weight. people who