Each day, we make thousands of goal-directed decisions. We decide to get out of bed, choose what to wear, and whether or not we will have breakfast. If we decide to have breakfast, we add several branches to our mental decision-making tree. Food-related decisions are affected by many factors, for example, tastiness, availability, convenience, environmental cues, and even personal long-term health goals.

A study published last month in The Journal of Neuroscience provides evidence that dietary self-control exists at an anatomical level in the brain. Researchers found that individual differences in brain anatomy prevent some people from making healthier food choices as easily as others.

Scientists analyzed MRI and choice data from three previously published studies. Choice data refers to tasks in which participants were asked to choose between different food items, basing their decisions on the healthiness of the foods.

The differences found in the grey matter volume of the ventromedial prefrontal cortex (vmPFC) and dorsolateral prefrontal cortex (dlPFC) between participants revealed that the higher the grey matter volume in these areas, the better a person was at exercising dietary self-control. The breakthrough study provides a potential biological explanation and general marker for self-control abilities.

“The general mechanism of these brain areas is to turn down response to food items when individuals try to self-regulate their food choices,” said Dr. Cendri Hutcherson, co-author of the study and Director of the Toronto Decision Neuroscience Lab.

A secondary question focused on whether anatomical differences observed depend on regulatory strategy. Analysis of a fourth study that used a slightly different choice task showed that the structure of the vmPFC and dlPFC predicted self-control abilities, regardless of strategy. Hutcherson explains that people could simply be telling themselves they do not want a certain food, as opposed to justifying their decision based on healthiness.  

In today’s obesogenic world, it is increasingly important to understand what drives individual eating behaviours, and why some fail to make healthy food choices more frequently than others. In less than half a century, the prevalence of overweight and obese individuals has increased rapidly, and comorbidities including type 2 diabetes and cardiovascular disease have followed the same trend.

The study is especially important for understanding the neuroscience behind eating disorders. “This study has important implications for understanding disorders like bulimia, [when] individuals go on binge eating episodes and they have trouble stopping themselves from eating foods even though they know it is not healthy,” said Hutcherson. The severity of such disorders may be related to a malfunctioning of the vmPFC and dlPFC.

Future studies may attempt to determine what influences the vmPFC and dlPFC, which could lead to the development of medical interventions that help strengthen the two brain regions.