Everywhere in the world, the richest people build the biggest homes, but as the world's wealthiest nation, the United States is also building the biggest bodies. It's hardly cause for patriotic pride. The obesity epidemic arrived with astonishing speed. After tens of thousands of generations of human evolution, flab has become widespread only in the past 50 years, and waistlines have ballooned exponentially in the last two decades. Today, Americans eat 200 calories more food energy per day than they did 10 years ago.
The most powerful technology driving the obesity epidemic is television. The best single behavioral predictor of obesity in children and adults is the amount of television viewing. Everybody thinks it's because TV watching is sedentary, you're just sitting there for hours--but that's only about one-third of the effect. The other two-thirds is the effect of advertising in changing what you eat.
Harvard Magazine May June 2004