Portion-control test has surprise

Experiment hints people want smaller servings when ordering fast food

WASHINGTON — Call it the alter-ego of super-sizing. Researchers infiltrated a fast-food Chinese restaurant and found up to a third of diners jumped at the offer of a half-size of the usual heaping pile of rice or noodles — even when the smaller amount cost the same.

Giant portions are one of the culprits behind the epidemic of bulging waistlines, and nowhere is the portion creep more evident than in restaurants with french-fry-heavy meal deals or plates overflowing with pasta.

Now, scientists are tapping into the psychology of eating to find ways to trim portions without people feeling cheated — focusing on everything from the starchy sides to the color of the plates.

“The small Coke now is what used to be a large 15 years ago,” said psychologist Janet Schwartz, a marketing professor at Tulane University who led the Chinese-food study.

“We should ask people what portion size they want,” instead of large being the default, she said.

Restaurants are paying close attention, said prominent food-science researcher Brian Wansink of Cornell University.

His own tests found children were satisfied with about half of the fries in their Happy Meal long before Mcdonald’s cut back the size and the calories last year.

“We’ll be seeing some very creative ways of downsizing in the next couple of years,” predicted Brian Wansink, author of “Mindless Eating: Why We Eat More Than We Think.”

But let’s call it “rightsizing,” said Dan Ariely, a Duke University behavioral economist. Rightsize suggests it’s a good portion, not a cut, he said.

So, Schwartz and Ariely experimented at a popular Chinese franchise at Duke University.

In the serving line, customers pick the rice or noodles first. The standard serving is a whopping 10 ounces, about 400 calories even before ordering the entree, Schwartz said. There was no half-size option on the menu board.

In a series of experiments, servers asked 970 customers after their initial rice or noodle order: “Would you like a half-order to save 200 calories?”

Those who said yes didn’t order a higher-calorie entree to compensate. Weighing leftovers showed they threw away the same amount of food as customers who refused or didn’t get the option.

A 25-cent discount didn’t spur more takers. Nor did adding calorie labels so people could calculate for themselves, the researchers reported in this month’s issue of Health Affairs.

They concluded that the up-front offer made the difference.

Anywhere from 14 percent to 33 percent chose the reduced portions, depending on the day and the mix of customers.

Even 200 fewer calories can add up over time. And other tricks can trim portions without people noticing, whether dining out or at home.

Cornell’s Wansink found that people put 18 percent more pasta with marinara sauce onto a red plate than a white one — and 18 percent more pasta alfredo onto a white plate.

A stark contrast “makes you think twice before you throw on another scoop,” Wansink said.