Heavier patrons, on the other hand, are "speed eaters"; they start serving themselves on large plates without scouting the spread, face the food, use forks and keep the napkin on the table, according to the research.

The study of 213 diners observed at 11 Chinese buffet restaurants across the United States is published in the August issue of the academic journal Obesity by Brian Wansink, Cornell's John S. Dyson Professor of Marketing, and Collin Payne, a Cornell postdoctoral researcher.

"Folk wisdom has suggested various ways to control portions and overeating, but this is one of the first studies to actually examine and find a correlation between behavior and body weight," said Wansink, who is on leave until January 2009 to take a 14-month appointment as executive director of the U.S. Department of Agriculture's Center for Nutrition Policy and Promotion. "The results are pretty striking."

The study employed 22 trained observers to code behaviors of patrons and estimate age, height and weight, putting them either into a low, middle or high body mass index (BMI) category.

They observed, for example, that persons with a lower BMI left more food on their plates and chewed about 15 vs. 12 times per bite.

"Increased chewing per bite of food has been shown to be related to lower BMIs partly because of the influence of chewing on satiety," said Wansink, author of "Mindless Eating: Why We Eat More Than We Think."

The behavior of heavier eaters, Wansink said, also suggests they are rushing -- they chew less, use forks, keep the napkin where it's handiest.

"The faster you eat, the more you miss the signals of being full," said Wansink. "Speed eating seems to be more prevalent in heavier people."

Provided by Cornell University