NEW YORK (REUTERS).- We've been overeating our way through ever-larger portions over the past 1,000 years, a U.S. study revealed after studying more than 50 paintings of the Biblical Last Supper.

The study, by a Cornell University professor and his brother who is a Presbyterian minister and a religious studies professor, showed that the sizes of the portions and plates in the artworks, which were painted over the past millennium, have gradually grown by between 23 and 69 percent.

This finding suggests that the phenomenon of serving bigger portions on bigger plates, which pushes people to overeat, has also occurred gradually over the same time period, said Brian Wansink, director of the Cornell Food and Brand Lab.

"The last thousand years have witnessed dramatic increases in the production, availability, safety, abundance and affordability of food," Wansink, author of "Mindless Eating: Why We Eat More Than We Think," said in a statement.

"We think that as art imitates life, these changes have been reflected in paintings of history's most famous dinner."

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

The study found that, over the past 1,000 years, the size of the main meal has progressively grown 69 percent; plate size has increased 66 percent and bread size by about 23 percent.

The research, conducted with Wansink's brother, Craig Wansink, a professor of religious studies at Virginia Wesleyan College, was published in the April edition of The International Journal of Obesity.

(Writing by Miral Fahmy, Editing by Steve Addison)