It’s not a matter of counting, just looking.
The study showed that when food images appeared with the calorie content, the brain showed decreased activation of its reward system and increased activation in its control system.
A desire to eat something is often strongly driven by the perceived tastiness of the food. However, when calorie information is added to the picture, it presents a second, competing source of information and influences the brain’s response.
Hopefully, this means that food that you might otherwise be inclined to overindulge in – particularly during food-centric holidays – becomes less desirable once its calorie content is displayed.
The study, published in the journal PLOS ONE, was conducted at Dartmouth College, a private Ivy League research university in New Hampshire.
It follows a move, by several public health departments throughout the US, to mandate that restaurants publish calories at the point of purchase, in menus and on menu boards.
To determine whether this information successfully changes a food’s appetitive value, this study put participants into functional MRI machines and scanned their brains while they viewed pictures of food with and without calorie information.
As this happened, their desire to eat the food was rated.
When the images were paired with calorie information, self-reported desire to eat the food decreased. At the same time, activation of brain regions that motivate eating behaviour decreased while activation of self-control, from the fronto-parietal control system, increased.
Whether the effect of providing calorie information will last is not known. People may simply become habituated to seeing the information in fast-food restaurants and begin disregarding it.
The study also aimed to evaluate the sensitivity of dieters’ and non-dieters’ brain responses. While both rated calorie-labelled foods as less appetising, the effect was strongest among dieters.
The results suggest they spontaneously consider calorie information even when it is not explicitly present.
The researchers found some evidence for this within the brains’ reward regions. Dieters had more similar activation patterns in part of the orbitofrontal cortex for both labelled and unlabelled foods.
As they have more experience or a stronger motivation to consider calorie information, they may do it more naturally.