The calorie counter in your brain

Portfolio, Science Writing

This Halloween, there will be many opportunities to eat unhealthfully, and today I’m going to speak with Jamie Pope of Vanderbilt University about some of the factors that come into play when we’re choosing what to eat.

Specifically, a study published recently in the Journal of Psychological Science suggests that we have a so-called “internal calorie counter” that evaluates foods based on their caloric density. The study, led by Alain Dagher, Deborah Tang, and Leslie Fellows of McGill University in Montreal, Canada, revealed that people cannot accurately estimate the number of calories of foods like potato chips and carrot sticks.

When participants tried to explicitly state the caloric content, scans of their brains showed activity in an area of the brain that processes sensory properties. When participants were asked to bid on foods, their willingness to pay correlated with the actual caloric density, and scans showed activity in a higher-order region of the brain that tracks the value of external stimuli.

Jamie is a professor of nutrition at Vanderbilt University in Nashville, Tennessee, with a background in obesity and weight management research. I asked her some questions about the study, and here are her answers:

What does the term “caloric density” mean? 

Caloric density is the number of calories in a given weight of food. It can be measured in ounces, it can be measured in pounds. So it’s how many calories are in an amount of food.

Speaking of caloric density, it’s interesting to note that foods that are more calorically dense tend to be foods or are foods that are higher in total fat content and higher in total sugar content, and often have not much water in their weight. So for example, a fried food would have more calories in it than a food that was not fried in the fat. Things like baby carrots versus Cheetos: a cup of each would be vastly different, or the same weight of each would be vastly different, in terms of their caloric density.

A popular habit among both healthy college students and people trying to manage their weight is tracking one’s energy consumption and expenditure throughout the day with calorie-counting apps. Given that this study points to implicit knowledge of calorie content, what would you say about counting calories?

Well, from what I understand from the study, the students—and they were normal weight—when they were asked to estimate calories in foods, they weren’t always very accurate. And yet, when they were asked how much they would value or how much they would pay for a given food, they tended to value more and be more willing to pay more for foods that are very calorically dense.

So what that’s telling me is that we have a biological component to how we choose foods, that’s kind of beyond knowledge, and that we are almost inherently attracted to foods that are high in caloric density. They are just are more appealing to us, potentially, sensory-wise, and that we may have this built-in mechanism that we go for the caloric foods, because they fuel us, and they provide energy to us. 

Because it seems that many people are pretty inaccurate in estimating calories themselves, that having some sort of app, some sort of resource you could turn to that actually accurately gauged calories might give you a better estimate of what you’re actually consuming.

Now that you’re aware of what your brain knows, and doesn’t know, about your food choices, it’s time to go have a happy, and healthy, Halloween.

Citations

Tang, D. W., Fellows, L. K., and Dagher, A., 2014, Behavioral and Neural Valuation of Foods Is Driven by Implicit Knowledge of Caloric Content: Association of Psychological Science. doi: 10.1177/0956797614552081.

Association for Psychological Science, 2014. Brain activity provides evidence for internal “calorie counter”: ScienceDaily. Published online at ScienceDaily.com.

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