While “supersizing” food portions in the U.S. is fairly common, recent research shows that when given the option, restaurant patrons actually opt to downsize portions.

The study published in the journal Health Affairs found when given the option to downsize their meals about a third of customers at a fast-food Chinese restaurant chose a smaller portion — cutting about 200 calories from their meals in the process. The patrons were unaware they were being watched when given this option.

Researchers found those diners left just as much uneaten food on their plates as everyone else, leading to an assumption that being served less didn’t make them feel deprived.

Lead study author Janet Schwartz, a behavioral psychologist at Tulane University, told ABC News that a big problem with many failed approaches to dieting is that “substituting a salad for a Big Mac is not an appealing choice” — so she believes easily-accessible calorie counts haven’t led to eating healthier foods.

She said downsizing may help with portion control, and 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.”

“Culturally, Americans do not respond to the cue of ‘feeling full,’’ she adds. “The cue to stop eating is only when the plate is empty.”