If you binged for two weeks while on vacation and gained 5 pounds, would you be biologically primed to eat less to compensate and shake off the excess weight? No, suggests a new Cornell University study.
When a group of 12 normal-weight men and women, average age 31, agreed to overeat by 35 percent for two weeks, they gained an average of 5 pounds, half of it body fat. When they were permitted to return to their normal eating behavior, they did not spontaneously cut back on their normal food intake, even after the two weeks of "feeling stuffed." Rather, they ate just as much as they did before the overeating period, as measured by the researchers during the two weeks before their binge began.
"The study suggests that eating behavior does not normally respond to internal cues, such as physiological mechanisms involved in the regulation of body weight, but to external cues," said David Levitsky, professor of nutritional sciences and of psychology at Cornell. "In other words, when the subjects returned to the same environment -- in this case our eating lab -- they returned to their same eating patterns, regardless of any biological signals."
The results add to the growing evidence that environmental cues, especially portion size, appear to be a major determinant of how much we eat, he said. This finding runs counter to the current view that food intake is largely determined by biological mechanisms.
The study is published in Physiology and Behavior (Vol. 84 (5), pp. 669-675) and was co-authored by Eva Obarzanek, a nutritionist for the National Heart, Lung and Blood Institute of the National Institutes of Health, Gordana Mrdjenovic, Cornell Ph.D. '00, and Barbara Strupp, associate professor of nutritional sciences at Cornell.