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Brent McFerran
Brent McFerran Ph.D.

Where do obesity myths originate?

Why people are so wrong about what causes obesity

People's beliefs about the causes of obesity can affect their own body weight. Of course, losing or maintaining weight is one of the most frequently reported goals people have, but when it comes to figuring out how best to lose weight (or what causes obesity), there is considerable bad advice out there. New research suggests that large food and beverage companies are partly to blame.

A quick scan of headlines demonstrates the clearly contradictory advice people face:

'Exercise holds key to keeping weight off.'[i]

'An hour of daily exercise 'needed to stay slim''[ii]

‘Why exercise won’t make you thin’[iii]

'Diet not exercise, plays role in weight loss.'[iv]

'Fat gene found by scientists.'[v]

'Scientists debunk so-called fat gene.'

Clearly, not all of these can be true? So which is most accurate?

If you ask true experts, such as editors of the Journal of the American Medical Association in a recent editorial, they conclude, "clearly, environmental causes of obesity are far more influential than genes… Obesity results from overnutrition and the primary therapeutic target is preventing or reversing overeating.... Exercise is associated with weight loss but its duration or intensity has minor effects on weight loss relative to diet.[vi] In other words, diet matters most, and exercise and genetics play supporting roles.

But are everyday consumers (i.e., laypeople) aware of the central role of diet? In other research[vii], we show that about half of people are misinformed about the central cause of obesity, and those who (correctly) believe diet to be the cause of obesity are indeed less likely to be overweight or obese. So how and why do people still believe that obesity can be solved by exercise alone, or that genetics can explain how obesity tripled over the past 50 years?

In a paper in California Management Review, Aneel Karnani (University of Michigan), Anirban Mukhopadhyay (Hong Kong University of Science and Technology) and I examine some reasons why regular laypeople (i.e., not medical professionals) are so misinformed about what causes obesity. We argue that food and beverage companies are partly responsible for the misinformation many consumers have. These companies consistently overemphasize the role of exercise as the cause of obesity—something we call 'leanwashing.' We argue that leanwashing is partly why so many people are misinformed about the true cause of obesity, thus leading to their actually being overweight.

Why blame companies? In fact, virtually every food company—in its CSR statement—proclaims its commitment to be a "part of the solution" to the obesity problem.

However, the food companies have a fiduciary responsibility to their shareholders to target growth and increase profits. This creates a dilemma for the food companies. Even if they wanted to combat obesity, it would be hard to do so without harming the profits they are required to deliver.

While not ascribing malicious intent, we argue that at the very least, many companies have a financial interest in the public being misinformed about the role of diet (versus exercise) in weight gain. Our research indicates that the food industry’s messaging on this topic biased and inconsistent with the scientific evidence. We argue that companies undertake four actions that obfuscate the cause of obesity to regular consumers: public statements, lobbying, exercise philanthropy, and sports sponsorship. In all of these actions, the central good is to deflect the role of diet in the cause of obesity.

For instance, in analyzing public statements by companies and their top executives, we found they commonly argue that lack of exercise or sedentary lifestyle is the primary cause of obesity. For example, here is an excerpt from a CNN interview with Indra Nooyi, the chairman and CEO of PepsiCo:[viii]

Interviewer: [Foreigners] see Americans and say they are obese. They say it is because of the snacks and fast food and high calorie drinks.

Indra Nooyi: I wish the solution was that simple. I can turn it around and say. I'll give you an example. When I was a kid, I would come home from school, throw my bag, go out to play. My daughter comes home from school, throws her bag, goes to play, but sitting in front of the computer because her definition of play has changed. They don't go out to play. Lifestyles have changed.

In an interview with Fortune magazine, Indra Nooyi went further and claimed "If all consumers exercised, did what they had to do, the problem of obesity wouldn't exist."[ix] While Ms. Nooyi is not a medical professional, her (incorrect) advice still forms part of the narrative that consumers hear, and the result is the creation and perpetuation of false beliefs in consumers.

Next, we examined lobbying efforts. The food industry uses lobbying "front groups" with consumer-oriented names that obfuscate their industry connections, such as Center for Consumer Freedom (CCF) and Americans Against Food Taxes (AAFT). The CCF website (erroneously) states, "A hefty number of studies has shown that the trend of rising obesity rates can be attributed not to increased intake of food in general (or any particular food) or to the influence of restaurants, but rather to less physical activity compounded by a variety of other factors that are constantly being explored." [x] Again, it is no wonder consumers are misinformed when the science cannot easily be distinguished from fiction.

Third, we examined what we termed, “exercise philanthropy,” or food companies’ targeted philanthropic donations to encourage people, often children, to exercise more—often through the building of playgrounds and activities featuring (unhealthy) food characters. As one example, Kellogg’s ‘Get in Step’ used Tony the Tiger to target children to exercise more (and presumably also eat more cereal). While exercise has many benefits, such actions are also an effective way to position the firms as part of the solution to the obesity crisis, rather than the problem.

Finally, we show companies try to associate themselves with exercise. The two most common means to achieve this are by endorsing high profile athletes and by sponsoring athletic leagues and events. Unfortunately athlete-endorsed food and beverages tend to be disproportionately high in sugar, salt, and fat, and the target market often children.

Promoting exercise is a worthwhile public health endeavor for many reasons, but it is not sufficient to result in sustained weight loss for most people. By focusing on exercise, companies direct attention away from policies that target food. According to science, the latter is more important if we are to combat obesity effectively.

Overall, our recommendation is for systematic and coordinated public health communications promoting the fact that intake is the primary cause of obesity. Not only would this increase awareness among laypeople, it would also help fight obesity, as well as reduce the incidence of leanwashing.

Karnani, Aneel, Brent McFerran, and Anirban Mukhopadhyay (in press), “Leanwashing: A Hidden Factor in the Obesity Crisis”. California Management Review.

Paper available here:


[i] Colihan, Kelley (2008), “Exercise Holds Key to Keeping Weight Off,”….

[ii] BBC News (2010), “An Hour of Daily Exercise Needed to Stay Slim’,”

[iii] Cloud, John (2009), “Why Exercise Won't Make You Thin,”,9171,1914974,00.html.

[iv] LiveScience Staff (2009), “Diet, Not Exercise, Plays Key Role in Weight Loss,”

[v] Available at: [Accessed December 11, 2013]

[vi] Livingston, Edward and Jody W. Zylke (2012), “JAMA Obesity Theme Issue. Call for Papers,” Journal of American Medical Association, 307 (9), 970–71.

[vii] McFerran, Brent and Anirban Mukhopadhyay (2013), “Lay Theories of Obesity Predict Actual Body Mass,” Psychological Science, 24 (8), 1428-1436.

[viii] Fareed Zakaria GPS (2011), “Interview with Indra Nooyi,”

[ix]Mangalindan, J.P. (2010), “PepsiCo CEO: If All Consumers Exercised...Obesity Wouldn't Exist,”….

[x] See and Obesity Myths, “Home,”

About the Author
Brent McFerran

Brent McFerran, Ph.D., is an assistant professor of marketing at the Beedie School of Business, Simon Fraser University.

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