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A computer analysis of the food depicted in some of the best-known paintings of the biblical Last Supper found that the portion and plate sizes depicted has increased substantially over the years.

The researchers analyzed 52 paintings depicting the Last Supper which were featured in the 2000 book "Last Supper," and used computer-aided design technology to analyze the size of the main meals, bread and the plates relative to the average size of the disciples' heads.

The findings suggest the trend of bigger plates and portions that has been noticed recently and linked to obesity may have been in the works for much longer, the researchers suggest.

"I think people assume that increased serving sizes, or 'portion distribution' is a recent phenomenon," said Brian Wansink, director of the Cornell Food and Brand Lab. "But this research indicates that it's a general trend for at least the last millennium."

In his lab, Wansink and his colleague investigate eating behaviors and how they might link to the current obesity epidemic in the United States and elsewhere. One factor they have linked to being overweight is large food portions, which can cause people to overeat.

Wansink teamed up with his brother Craig Wansink, a religious studies professor at Virginia Wesleyan College, to look at how portion sizes have changed over time by examining the food depicted in 52 of the most famous paintings of the scene from the Last Supper.

"As the most famously depicted dinner of all time, the Last Supper is ideally suited for review," Craig Wansink said.

From the 52 paintings, which date between 1000 and 2000 A.D., the sizes of loaves of bread, main dishes and plates were calculated with the aid of a computer program that could scan the items and rotate them in a way that allowed them to be measured. To account for different proportions in paintings, the sizes of the food were compared to the sizes of the human heads in the paintings.

The researchers' analysis showed that portion sizes of main courses (usually eel, lamb and pork) depicted in the paintings grew by 69 percent over time, while plate size grew by 66 percent and bread size grew by 23 percent.

Both Wansinks suggest that as food has become more available over the last millennium, the way people, including artists, view and depict food has changed accordingly, with the same dinner scene being viewed as having more on the table in more recent decades and centuries. The results of the study are detailed in the April issue of the International Journal of Obesity.

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