Weight loss changes people's responsiveness to food marketing

According to a new study by UBC Sauder School of Business Assistant Professor Dr. Yann Cornil (he/him/his) and French researchers, people with obesity do tend to be more responsive to food marketing -- but when their weight drops significantly, so does their responsiveness to marketing.

For the study, which was published in the Journal of Consumer Psychology, the researchers followed three groups: patients with severe obesity before they had gastric bypass or other weight-loss surgeries (collectively known as bariatric surgery), as well as three and 12 months after; people with obesity who were not undergoing bariatric surgery; and people who were not obese.

To measure their responsiveness to food marketing, the researchers evaluated what's called framing effects -- that is, how branding, advertising, and labeling "frame," and thus influence food evaluations and choices. In one study, participants were asked to estimate the calorie content in well-known snacks and drinks including some, which marketers typically framed as healthy (i.e. apple juice, granola bars), and others, which are not framed as healthy (i.e. soft drinks, chocolate bars).

The researchers found that everyone underestimated the calorie content of snacks that were framed as healthy but the effect was more pronounced in people with obesity.

To further test the framing effect, the researchers had participants hypothetically choose a portion of french fries from a fast food restaurant, and gave them the nutritional information they would need to make an informed decision. The three options were always the same in quantity -- 71g, 117g, and 154g -- but in one instance they were labeled small, medium and large, and in another instance the same portions were labeled mini, small and medium: a marketing tactic aimed at making larger portions seem more reasonable.

"We measured how likely people were sensitive to that framing, and whether it would change their choice of fries quantity depending on how the portions are labeled," explains Dr. Cornil, who says the people with obesity were more likely to follow the labeling and not the actual information about quantity -- so they would choose the portion labeled "medium" even though that's quite large.

Overall the researchers, who worked closely with the Pitié-Salpêtrière Hospital in Paris, found that the people with obesity tended to be more responsive to food marketing -- but when they lost a significant amount of weight because of bariatric surgery, their level of responsiveness to food marketing dropped substantially.

"People with obesity going through bariatric surgery will become less responsive to marketing over time," says Dr. Cornil. "And after 12 months, their responsiveness to marketing reaches the level of people with more medically-recommended weight."

Dr. Cornil says it's not clear whether people with obesity become less responsive to marketing because of physiological changes following the surgery -- hormonal, neurological shifts or changes to the gut microbiota -- or because of people's desire to change their lifestyles and habits. Another possible reason, he adds, is that people's tastes tend to shift following bariatric surgery.

"The results clearly suggest a bidirectional influence between people's weight status, psychology and responsiveness to the environment -- including marketing," says Dr. Cornil. "So, it's a complex relationship."

However, had the researchers found the responsiveness to marketing remained high even after weight loss, it would have pointed to a deeper-rooted predisposition.

"That would mean people are endowed with unchangeable psychological characteristics that would always make them more responsive to marketing -- which would make it very difficult to sustain a medically-recommended weight," he explains. "But one of the positive things is that after significant weight loss, people become less responsive to marketing, such that it is more sustainable to remain at a lower body mass index."

Dr. Cornil says the findings are especially important because for years, researchers have assumed that marketing messages -- especially for foods that are high-calorie and low in nutrition -- are at least partly responsible for the obesity epidemic, but there wasn't clear empirical evidence.

"Our results provide important insights for policy-makers in charge of regulating food marketing in order to curb obesity," says Dr. Cornil.