HKUST Business School Magazine

6 Research For reasons that may be very much about the bottom line, as it turns out. New research by Anirban Mukhopadhyay, Associate Professor of Marketing at HKUST, and Brent McFerran, Assistant Professor of Marketing at the University of Michigan, shows that people who think obesity is caused primarily by lack of exercise, rather than poor diet, tend to eat more, and therefore be heavier. By linking their food products to exercise, firms are capitalizing on that misperception. The two authors conducted the first investigation of laypeople’s own views on the cause of obesity, in five countries on three continents (Hong Kong, South Korea, the US, Canada and France). Participants provided their heights and weights (used to calculate body mass index, BMI) and responded to questions on their beliefs about obesity. In each instance, those who thought obesity was primarily due to lack of exercise had significantly higher BMIs than those who thought it was caused by diet. In Korea, for instance, the diet theorists in the study had a mean BMI of 21.55 versus 23.10 for exercise theorists (representing a difference of about 10 pounds for someone 5 feet 4 inches tall). This pattern was repeated in all countries, even controlling for other major factors known to affect weight, such as education, sleep deprivation, stress and medical conditions. “People’s beliefs guide their actions,” explained Professor Mukhopadhyay. “If we believe overeating is the cause of obesity and we want to lose weight, we cut our intake. But if we believe weight gain is mainly the result of insufficient exercise, we try to increase our physical activity.” This offers a window for marketers to sell their messages but it also contradicts medical research, which has shown it is much more difficult to rely on exercise for weight control than diet. “People often reward themselves for their exercise with an indulgent treat and end up consuming more calories than they burned off. They also generally overestimate how many calories they burn off in exercise and underestimate how many calories they eat. And most people do not have enough time in the day to truly exercise off the extra calories they eat,” he said. The new research also looked at participants’ actual eating habits by offering them chocolates in two of the studies. As expected, those who rated exercise as the main cause of obesity ate more chocolates. However, the authors also showed that this outcome could be manipulated. In the final study they had participants read a passage that either said exercise was the main factor in obesity, or diet was. Those who read the exercise passage ate more chocolates. “This finding suggests that simply informing people that eating too much is the main cause of weight gain could impede the obesity epidemic. People’s beliefs can change in response to public health campaigns from trusted sources so public health communications should focus on getting people to reduce the amount they eat, especially of high- calorie foods,” Professor Mukhopadhyay said. That may not be what food companies want to hear, but they have not yet heard the last on this topic. Professor Mukhopadhyay said they were doing further research to explore how major food- marketing companies are actively promoting the exercise lay theory. Diet, Exercise and Body Mass: We Eat as We Believe Food industry giants Coca-Cola and McDonald’s were among the sponsors of the 2012 Olympics. Kellogg’s launched a “Get In Step” campaign that encouraged people to walk then eat a bowl of cereal. The CEO of Pepsico responded to a question about her firm’s role in the obesity crisis by pointing out that children’s playtime had changed from running outside to sitting in front of the computer. Why are food companies interested in exercise? Based on: “Lay Theories of Obesity Predict Actual Body Mass” By Brent McFerran of University of Michigan and Anirban Mukhopadhyay of HKUST Business School Psychological Science - forthcoming Anirban Mukhopadhyay ©Donna Barstow 2013