The world population is growing fast: from 3 billion in 1960 to 6 billion in 2000 to 6.8 billion in 2010. If the world population continues to grow at the same pace, by the end of this century it will reach 12 billion. At the current childbirth rate of 2.6 children per woman, the population will continue to grow unless the fertility rate decreases or the mortality rate increases. Both are likely possibilities; the fertility rate has been declining and obesity-related diseases have decreased life expectancy. The current obese generation is expected to live a shorter life span than the previous nonobese generation.