American waistlines keep expanding, even though these days more of us—60 percent of the population versus 48 percent in 1991—are munching on “healthy” or lower-calorie foods. What gives?

 

It turns out consumers are grossly underestimating the number of calories in fare served at healthier fast food restaurants, say researchers Pierre Chandon, an assistant professor of marketing at INSEAD in Fontainebleau, France, and Brian Wansink, a professor of marketing at Cornell University in Ithaca, New York.

 

Here’s why our bad math is getting to be such a big problem. Since eaters believe they’re saving more calories than they really are on main dishes at chains like Subway, they opt to indulge in sugary sodas and desserts. Because of a “health halo” surrounding entrees presented as healthy, diners actually end up ordering drinks, desserts, and side dishes packed with up to 131 percent more calories than the extras they would have ordered if the main course was not advertised as healthy, the researchers say.

 

“Many people expected that the diffusion of ‘healthier’ food alternatives would slow down, or even curb rising obesity rates,” says Chandon. “It did not. The health halo is only one of the many factors, but probably an important one.”

 

The trend warrants study as so-called healthier restaurants, also known as fast-casual chains—places like Panera Bread and Café Express—are growing at up to 12.5 percent each year, about twice the rate of the overall restaurant industry, according to Technomic, a Chicago-based food industry consulting company. If the health halo is truly in effect, caloric overreaching may be widespread.

 

With two thirds of the U.S. population now overweight or obese, the public health implications of overeating are already well known. Obesity represents more than $100 billion in direct and indirect medical costs annually, according to the Centers for Disease Control.

 

In a series of four studies published recently in the Journal of Consumer Research, Chandon and Wansink examined the habits of hundreds of diners at McDonald’s, home of the Big Mac, and Subway, whose pitchman Jared Fogle famously advertises he lost 245 pounds in a year eating the chain’s sandwiches.

 

To be sure, Subway’s health claims are not just baloney. The typical Subway meal averages 694 calories, compared with 1,081 for the average meal at McDonald’s, the authors report. The problem is, when people patronize healthier Subway, their judgment of how many calories they’re consuming seems to go fuzzy. One study found that diners estimated that a 1,000-calorie meal had 159 fewer calories if they bought it at Subway instead of McDonald’s. Sounds harmless enough, but Wansink says that if consumers reacted by going to Subway twice a week for a 1,000-calorie meal and eating an additional 159 calories they thought they had saved, in a year, they would be five pounds heavier.

 

Things got worse when Subway diners were asked to estimate a large meal of

1,327 calories. They guessed 646 calories, less than half the actual amount.

McDonald’s diners were more realistic guessing the count of an equivalent high-calorie meal at the Golden Arches: 843 calories, only a third off the mark.

 

“Double the numbers you think you are eating and you are going to be a lot closer to the correct calorie count, especially if you are at a healthy restaurant,” says Wansink, who is the author of Mindless Eating: Why We Eat More Than We Think.

 

As for Milford, Connecticut-based Subway, the company says it’s doing what it can to educate consumers about what they’re eating. Spokesman Kevin Kane says the chain provides nutritional information for its foods online and, increasingly, on menu boards as more states require it. “We provide the information,” says Kane. “If someone says ‘I want to find a meal that is low-calorie’ and goes into a Subway, I think they will be very happy. But they have to do some legwork.”

 

It’s not just restaurants where many consumers seem to be falling down on their legwork. In a separate series of studies published last year, Chandon and Wansink found that simply labeling processed foods like M&Ms or granola as “low fat” led people to eat up to 50 percent more at home. “People think low fat means low calories and that it’s ok to splurge,” says Chandon. The truth is, Chandon says, food companies often replace fat with sugar so that low fat foods have on average 5 percent less fat, but only 5 percent to 10 percent fewer calories than their fattier versions.

 

To combat the health halo effect, Chandon and Wansink offer several suggestions. Educational campaigns could raise awareness, “encouraging people to examine critically the health claims associated with various restaurants and foods.” Most effective, they say, would be for consumers to fixate less on what’s healthy and not, and more on portion sizes. “When there is a lot, it is an indulgence, regardless of what it is,” says Chandon. Next time Subway shill Fogle says “It’s okay, I had Subway,” Chandon and Wansink are hoping the pitch will come with an asterisk.