By Dr. RACHEL MAY ADAMS

What if fast food chains offered consumers the option of "downsizing" a meal instead of "supersizing" it?  Would people actually opt to "downsize," or get less food, for the same amount of money? And, if people accepted the "downsize" option, would they actually consume fewer calories from the meal overall?

According to new research, this approach may actually work, on both counts.

In the study, published today in the journal Health Affairs, patrons at a fast-food Chinese restaurant in Durham, N.C., who were unaware they were being observed, were given the option to downsize their meals. Specifically, consumers who ordered a combination meal were given the option to receive a smaller portion of a side dish. About a third of people chose this option, and each of them cut about 200 calories from their meals.

The group that opted to downsize did not appear to feel deprived; they had an equivalent amount of leftovers as the regular group.

According to lead author Janet Schwartz, a behavioral psychologist at Tulane University, a big problem with many failed approaches to dieting is that "substituting a salad for a Big Mac is not an appealing choice." That's why she believes informing consumers of the amount of calories in food has not helped them to cut back on consumption.

"Just giving people health information, such as calorie labeling, does not change behavior," she said.

She and her co-authors surmised that when you present people with calorie information alone, the choices feels too restrictive.

"Downsizing," Schwartz said, is based on the idea that "getting people to think about a smaller side dish or beverage will help them to cut back without asking them to completely restrict themselves.

"Suggesting a smaller portion allows people to satisfy a desire for a food and does not force them to sacrifice what they want to eat," Schwartz said, adding that "downsizing" may also help people with portion control.  "Culturally, Americans do not respond to the cue of 'feeling full.' The cue to stop eating is only when the plate is empty."

In a previous study, the researchers found that consumers wouldn't ask for less food, but if offered, they would accept it. Past survey data also indicates that the majority of consumers believe restaurant portions are too large.

The owners of the fast-food restaurant where the study was conducted were initially concerned that patrons would be offended by being offered the smaller portions. But while that may have been true for some customers, it was not true for all, and the restaurant ultimately saved money because it served less food.

Consumers didn't mind being offered the option to downsize, and a small discount of 25 cents on smaller portions had minimal impact on patrons' choice to downsize.

"They thought that fast food customers just wanted more food - a lot of food for a little money," Schwartz said.  "['Downsizing'] was very cost effective for them."

If, as this study suggests, "downsizing" really is a marketable concept, then less may truly become more - to the great benefit of many American waistlines.