Showing the Calories in Fast Food Forces the Brain to Change its Response

Dartmouth-led research explains why the human brain has more aversion to fast food when the calories are presented next to it.

Seeing a picture of savory pizza might get mouths watering, but the human brain has a different response to that pizza when calorie information is posted next to it.

A new study from Dartmouth researchers explains why calorie content causes a significant change in why people avoid some of their favorite foods. 

The hunger for dieting

With a new year just around the corner, millions of people are considering revamping their diets and getting healthier with their eating. This often includes tracking calories -- a frustrating task, especially when one's favorite foods become more restricted.

Up to 50 percent of women are on a diet at any given point throughout the year, according to researcher Judy Mahle. Over 90 percent of teenagers regardless of gender attempt diets during their adolescence.

In America alone, people spend up to $43.6 billion on weight loss and dieting products.

However, the Dartmouth-led study suggested another fix -- seeing calorie labels -- might help people more than any magic diet pill. 

“Our findings suggest that calorie-labeling may alter responses in the brain’s reward system when considering food options. Moreover, we believe that nutritional interventions are likely to be more successful if they take into account the motivation of the consumer, including whether or not they diet,” said first author Andrea Courtney.

Courtney was a graduate student in the department of psychological and brain sciences at Dartmouth at the time of the study. She is currently a postdoctoral student at the Stanford Social Neuroscience Lab at Stanford University.

Obesity affected nearly 40 percent of adults in the United States in 2015-2016. Those figures and others caused the US Food & Drug Administration to institute a menu labeling law, requiring nearly all restaurants to post the number of calories found within meals. 

Behind the cravings and calories

While the menu labeling law forced people to come to terms with just how many calories were in their favorite McDonalds combo, it also did something else to their brain, according to the research. 

Dartmouth hosted 42 undergraduate students for the study. The group included 22 people who identified as "dieters" and 20 who did not. They viewed 180 images without calorie information and then viewed images with calorie information.

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The participants were then asked to rate their desire to eat the food from 1 (not at all) to 4 (would definitely eat) while going through an MRI scanner. 

Both dieters and non-dieters ranked the calorie-labeled pictures of milkshakes and fries as less appetizing. However, the researchers found a sharp response in dieters.

The team took a closer look at two brain regions responsible for eating behaviors: the nucleus accumbens and the orbitofrontal cortex. 

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All participants showed less activity in these areas when the calorie-labeled food appeared. However, dieters showed similar activity in the left orbitofrontal cortex when looking at both calorie-labeled and unlabeled foods.

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This suggested to researchers that dieters might be so used to considering calories that they've retrained their brain to naturally consider calories in food. 

The researchers hope the information can be used to help dieters and nondieters alike live healthier lifestyles. 

“In order to motivate people to make healthier food choices, policy changes are needed that incorporate not only nutritional information, including calorie content, but also a public education component, which reinforces the long-term benefits of a healthy diet,” added senior author Kristina Rapuano.

Rapuano was a graduate student in the department of psychological and brain sciences at Dartmouth at the time of the study.