Bad news, dieters. Adding an salad to your hamburger won’t help you lose weight. It’s a notion so simple it sounds ridiculous. But a new study says we underestimate the calorie content of a meal when it’s paired with a healthy item. The effect was even more pronounced in people concerned with their weight—what researcher Alexander Chernev calls a “dieter’s paradox.”
Dieters are most likely to succumb to the “negative calorie illusion” precisely because they are constantly evaluating food based on whether it is healthy or not, Chernev said. Once a person has classified a food as healthy or unhealthy, the negative calorie illusion is just a short mental step away. “It’s fairly rational to assume that if you have something unhealthy and you add something healthy to it, the combination is kind of healthier,” he said. “But what people do then is assume, ‘If it’s healthy, it must have fewer calories.’ ”
Chernev, an associate professor of marketing, surveyed nearly 1,000 people, split them into two groups, and had each group look at different pictures of food. For example, he showed one group a picture of a bacon-and-cheese waffle sandwich (I’m not kidding—these things exist) and asked them to rate the caloric content. Next, he showed the same gut-bomb sandwich to a different set of participants, but with a small organic apple on the side. After participants had assessed the offerings, Chernev asked how them concerned they were with their weight.
Participants thought the sandwich and apple pairing had fewer calories than the sandwich sans apple. The illusion was stronger among people who expressed concern about their weight, and is most deceiving when the healthy item is does not have many calories by itself, Chernev said.
There may be a silver lining in this news, though. Diets that emphasize calorie counting and portion control may help counter the negative calorie illusion since those approaches rely on more objective appraisals rather than snap healthy-unhealthy classifications. Still, the research suggests many diet plans may not have the right tools to help people lose weight.
“Just motivating people to lose weight and giving them the option is not enough. You also have to teach people how to think about this,” Chernev said.
Editor’s note: Alexander Chernev has a forthcoming book on his research titled The Dieter’s Paradox.
Photo by amanky.