Craving high-calorie snacks? Blame your brain

Overindulging in high-calorie snacks is partly caused by temporary lapses in a very specific part of the brain, according to a new University of Waterloo study.
 
The study, published in Psychosomatic Medicine: Journal of Biobehavioral Medicine, is the first to conclusively link reduced activity in the dorsolateral prefrontal cortex with weakened self-control around tasty but unhealthy snacks.
 
“It has long been thought that the dorsolateral prefrontal cortex helps to keep automatic or knee-jerk reactions in check,” said senior author Peter Hall, a professor in Waterloo’s Faculty of Applied Health Sciences. “We discovered that when you temporarily dampen the operation of this particular part of the brain, strongly engrained—and quite universal—preferences for high-calorie foods start to hijack people’s thoughts and even their eating patterns.”
 
Woman eyeing up a cupcake
 
The prefrontal cortex is known to be implicated in the brain’s executive functions, which allow for conscious control of reflexive responses to the environment.  While prior studies have shown that boosting activity in the prefrontal cortex reduces cravings for unhealthy foods, this is the first study to show that temporarily downgrading it increases craving and consumption of snack foods.
 
Researchers temporarily reduced activity in the study participants’ left dorsolateral cortex with magnetic stimulation, using a procedure called theta burst stimulation. After receiving theta burst stimulation, participants not only reported greater food cravings for calorie-dense food, but ate more junk food during a taste test than when they received a bogus stimulation.
 
“This is the first study to demonstrate that taking the prefrontal cortex temporarily offline results in increased snacking,” said Cassandra Lowe, doctoral student in Waterloo’s School of Public Health and Health Systems and lead author on the paper.

Exercise and sleep will improve brain health

The findings will provide a theoretical framework to help shape effective public health interventions, with a focus on preservation of brain health.
 
“The research suggests that improving brain health may be a fairly important avenue for fostering dietary self-restraint. Interventions aimed at enhancing or preserving dorsolateral cortex function in healthy populations may reduce the likelihood of obesity and other chronic conditions” said Hall.
 
Engaging in aerobic exercise, avoiding alcohol and getting enough sleep are proven methods of maximizing the strength of the prefrontal cortex.
 
“In the end, if you want to improve your self-control when it comes to snacking, structuring your environment to avoid temptations is crucial; but beyond this, the key is to keep your brain in shape, so that you are up to the task when you encounter temptations. Let’s face it, they are everywhere,” said Hall.