Why some people can't resist unhealthy food

The reason why some people cannot resist calorie-dense snacks even at the risk of gaining extra weight may be due to decreased activity in the dorsolateral prefrontal cortex (DLPFC), which is involved in the executive functions of the brain.

Executive function refers to a set of cognitive functions that enable "top-down" control of action, emotion and thought.

"Decreased DLPFC activity appeared to be associated with increased reward sensitivity - it made the participants more sensitive to the rewarding properties of palatable high caloric foods," the researchers said.

The results suggest that interventions aimed at enhancing or preserving DLPFC function may help to prevent obesity and related diseases.

"These findings shed light on the role of the DLPFC in food cravings (specifically reward anticipation), the consumption of appealing high caloric foods and the relation between self-control and food consumption," said senior study author Peter Hall from the University of Waterloo in Canada.

The study included 21 healthy young women, selected because they reported strong and frequent cravings for chocolate and potato chips.

The women were shown pictures of these foods to stimulate cravings.

The researchers then applied a type of magnetic stimulation, called continuous theta-burst stimulation, to decrease activity in the DLPFC.

After the theta-burst stimulation, the women reported stronger food cravings - specifically for milk chocolate and potato chips.

The study appeared in the journal Psychosomatic Medicine: Journal of Biobehavioral Medicine.