Kellogg World Winter 2010

Faculty bookshelf: Mind over matter? Fat chance

In The Dieter's Paradox, Alexander Chernev shows how healthy food choices can lead to unhealthy results

By Matt Golosinski

  Alexander Chernev

An apple a day has long been considered a folksy antidote to medical intervention. But new Kellogg School research shows that an apple — or salad or broccoli — might actually be contributing to America’s obesity epidemic in a surprising way.

People seem to believe that these healthful choices exert a kind of magical effect when added to a plate already heaped with rich food. A study and forthcoming book by Associate Marketing Professor Alexander Chernev show that people believe that adding a healthy option can reduce a meal’s overall calories.

“An important factor contributing to the obesity epidemic is a misguided belief about the relationship between a meal’s healthiness and its impact on weight gain,” says Chernev, an expert on consumer behavior and managerial decision-making. “People intuitively believe that eating healthy foods in addition to unhealthy ones can decrease a meal’s calorie count.”

Chernev’s findings will be published in the April 2011 Journal of Consumer Psychology, as well as in his upcoming book The Dieter’s Paradox: Why We Fail to Achieve What We Want Most.

As part of Chernev’s study, participants were asked to estimate the caloric content of several meals. Some were shown relatively unhealthy meals, while others were shown the same meals combined with a healthy option. For example, some participants were presented with a bowl of chili with cheese, whereas others saw the same bowl of chili paired with a small salad.

The result? Those shown only the bowl of chili estimated it to have about 699 calories. Those shown the same bowl of chili paired with the salad, however, estimated the chili to have just 656 calories. Thus, people believed that adding the salad to the meal essentially subtracted 43 calories from the chili — a rather stunning conclusion, given that the salad alone was estimated to contain 62 calories.

Even more striking is that this phenomenon — which Chernev calls the “negative calorie illusion”— was more prevalent among supposedly calorie-wise dieters. In fact, the negative calorie illusion was more than three times stronger for those concerned about their weight than for non-dieters.

Chernev says this “dieter’s paradox” does not seem to be caused by a lack of nutritional information. If anything, recent years have seen an increase in consumer awareness and information about diet. The disconnect, Chernev believes, is due to the fact that people don’t know how to use this information in ways that help them achieve their health goals.

“We are given a lot of information. What we lack is knowledge,” he says. “Information is what we see on food labels. Knowledge, on the other hand, reflects our ability to re-think and align our behavior with our goals. My basic premise is that to change our behavior, we first need to gain knowledge.

“Simply motivating consumers to diet without providing them with adequate knowledge can lead to counterproductive choices that facilitate weight gain rather than weight loss,” Chernev says — an insight with important implications for public policies aimed at improving health.

Chernev also explores other fallacies people are prone to in their quixotic quest to stay fit. He argues that Western thinking — as well as indulgent Western food and the sedentary Western lifestyle — are among the key factors contributing to the obesity epidemic.

A prolific scholar with numerous publication credits in leading journals, Chernev says his research into the dieter’s paradox was inspired by his ongoing interest in consumer decision-making and compensatory reasoning.

So what’s on the professor’s plate? Chernev says he’s not on a diet, but always adds healthy options to indulgent meals. His website is



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