In a study just published by the International Journal of Obesity, Cornell marketing professor Brian Wansink teams up with his brother Craig Wansink, a professor of religious studies at Virginia Wesleyan College, to show that food portions depicted in paintings of the Last Supper get bigger as time goes by. The Brothers Wansink compared the size of the bread and the main dish to the average size of the diners' heads in 52 Last Supper paintings spanning 1,000 years. They found that "the relative sizes of the various dishes have increased in a linear fashion over the past millenium." Specifically, "the main dish (entree) has increased by 69 percent," "the bread has increased by 23 per cent," and "the size of the plates has increased by 66 per cent."
It's plausible, as the authors suggest, that the trend reflects a growing abundance of food, but whatever portion expansion was occurring in the real world clearly was not enough to cause an "obesity epidemic," a phenomenon observed only in the last few decades. In addition to increased calorie intake, expanding wastlines in developed countries reflect reduced calorie burning as the need for back-breaking labor has steadily declined. But again, that trend began long before Americans and other Westerners started becoming noticeably fatter in the 1980s.
I reviewed Brian Wansink's book Mindless Eating in the January 2008 issue of Reason.