Hugh Pickens writes "The NY Times reports that Carson C. Chow, an MIT-trained mathematician and physicist, has taken a new look at America's obesity epidemic and found that a food glut is behind America's weight problem, with the national obesity rate jumping from 20 percent to over 30 percent since 1970. 'Beginning in the 1970s, there was a change in national agricultural policy. Instead of the government paying farmers not to engage in full production, as was the practice, they were encouraged to grow as much food as they could,' says Chow. 'With such a huge food supply, food marketing got better and restaurants got cheaper. The low cost of food fueled the growth of the fast-food industry. If food were expensive, you couldn't have fast food.' Chow and mathematical physiologist Kevin Hall created a mathematical model of a human with hundreds of equations, boiled it down to one simple equation, and then plugged in all the variables — height, weight, food intake, exercise. The slimmed-down equation proved to be a useful platform for answering a host of questions. For example, huge variations in your daily food intake will not cause variations in weight, as long as your average food intake over a year is about the same. Unfortunately, another finding is that weight change, up or down, takes a very, very long time. Chow has posted an interactive version of the model on the web where people can plug in their information and learn how much they'll need to reduce their intake and increase their activity to lose."