October 20, 2015

Cornell Study Links Weight Bias to Food Perception

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What makes a recipe appear healthy? According to a recent Cornell study for Health Communication, social media users can be influenced by a thin versus heavy weight bias to roughly the same extent as by nutritional information when making judgments about a meal’s healthiness.

“Prejudice and the Plate: Effects of Weight Bias in Nutrition Judgments,” published by Prof. Jonathon Schuldt, Prof. Geri Gay and postdoctoral associate Jamie Guillory, all of the communication department, found that the weight of a social media user who posts food images has an effect on the perceived healthiness of that food.

Schuldt, the first author of the study, says health information on social media sites or blogs is becoming increasingly popular, but it is rarely objective from a scientific perspective.

“Because these things have a social element, it’s often not just content about the food itself — that content is often associated with a person,” Schuldt said.

This social aspect of health information led the research team to question whether weight bias might change viewers’ evaluation of food images or recipes, according to Schuldt.

“Our question was simply this — might the body weight of a person who the food is associated with influence how the food itself is perceived?” he said.

To find out, the research team showed over 200 participants 10 images of food that appeared to be posted to a social media site by a specific user. The thumbnail photo the participants were shown was a real photo of a woman either before or after she had lost weight.


In a study conducted by Cornell researchers, the above image was judged as more unhealthy when it was presented alongside a picture of an an overweight woman as opposed to a woman of “normal weight.” (Courtesy of Prof. Jonathon Schuldt)

The participants were randomly assigned to view the food images as posted by the “overweight” woman or the woman of “normal” weight. They were then asked to rate how healthy each food image was on a scale from one to seven.

“What we found was not surprising — that, on average, the same set of meals are perceived as less healthy when they are posted by the heavier-appearing woman,” Schuldt said.

These results showed that weight bias has a significant correlation with perceived healthiness when nutritional information is not given. The research team then decided to take their investigation one step further.

“In the second study, we wanted to see whether we would still get this effect if we actually gave people nutritional information — which is much more relevant to whether this food is healthy than the person associated with it,” Schuldt said.

The researchers showed participants the same food and thumbnail images as they had in the first experiment, but they added fake nutritional information underneath each food image. Half of the participants were shown “healthy” nutritional information, while the other half were shown caloric and fat values that were much higher. Once again, the participants were asked to rate the healthiness of the food.

As expected, the participants who viewed the food images as being higher in calories and fat rated them as less healthy. The surprise was that the effect of weight bias on perceived healthiness was found to be just as strong as the effect of the caloric and fat increase.

“It’s not surprising that we found these effects, [but] it’s surprising how strong these effects are,” Schuldt said.

Many people do not fully understand how to interpret nutritional information, Schuldt added. Because turning to online sources for simple, easily accessible food information has become so common, the combination of an uninformed public and factors like weight bias could influence the population’s nutritional decisions.

“We think that there are direct, practical implications of this work, really for all of us that use the Internet,” he said.

Schuldt said he hopes that this study will highlight the difficulties of choosing food that is truly healthy. Many people have health goals they actively try to meet, but it becomes harder to do so when nutritional judgments are not made correctly.

This study has implications even outside of the context of food blogging and health, according to Schuldt. Weight bias is only one factor that influences decisions but that few people give much thought to.

“It’s a reminder that there are social biases that pervade society, and that our judgments are less objective than we think they are,” Schuldt said.