A new study finds a link between overindulging in junk food and lapses in brain function. The new University of Waterloo study, which was published in Psychosomatic Medicine: Journal of Biobehavioral Medicine, is the first to decisively connect a reduced operation of the dorsolateral prefrontal cortex with dietary self-restraint.

The study’s senior author, Professor Peter Hall, said in a statement, “It has long been thought that the dorsolateral prefrontal cortex helps to keep automatic, or knee-jerk, reactions in check.” He continued, “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 thought patterns and even their eating patterns.”

The prefrontal cortex assists in the brain’s primary functions, which generally enable individuals to voluntarily control their behavior. Previous studies have shown that increasing activity in the prefrontal cortex helps to reduce cravings for junk food, but this study is the first to show that a reduction in activity leads to increased cravings and food consumption.

The study used a type of transcranial magnetic stimulation called continuous theta burst stimulation to temporarily lower activity in the left dorsolateral cortex among patients. Once they received the theta burst stimulation, patients reported greater cravings for calorie-rich food, but ate more junk food in a taste test than they did when receiving a bogus stimulation.

According to statisticbrain.com, there are approximately 160,000 fast food restaurants in the U.S., with 50 million Americans served each day.