A study conducted by researchers at FAU Erlangen-Nuremberg, Germany, sheds new light on the causes of hedonic hyperphagia, a condition that plagues hundreds of millions around the world.

Hedonic hyperphagia – eating for pleasure independent from hunger – is a phenomenon almost everybody knows.

“It’s recreational over-eating that may occur in almost everyone at some time in life. And the chronic form is a key factor in the epidemic of overweight and obesity that here in the United States threatens health problems for two out of every three people,” explained lead author Dr Tobias Hoch, who presented the findings at the 245th National Meeting & Exposition of the American Chemical Society.

The scientists allowed one group of laboratory rats to feast on potato chips. Another group got bland old rat chow. They then used high-tech magnetic resonance imaging devices to peer into the rats’ brains, seeking differences in activity between the rats-on-chips and the rats-on-chow.

“The effect of potato chips on brain activity, as well as feeding behavior, can only partially be explained by its fat and carbohydrate content. There must be something else in the chips that make them so desirable,” Dr Hoch said.

The rats were offered one out of three test foods in addition to their standard chow pellets: powdered standard animal chow, a mixture of fat and carbs, or potato chips. “They ate similar amounts of the chow as well as the chips and the mixture, but the rats more actively pursued the potato chips, which can be explained only partly by the high energy content of this snack. And, in fact, they were most active in general after eating the snack food.”

“Although carbohydrates and fats also were a source of high energy, the rats pursued the chips most actively and the standard chow least actively. This was further evidence that some ingredient in the chips was sparking more interest in the rats than the carbs and fats mixture,” Dr Hoch said.

The researchers mapped the rats’ brains using Manganese-Enhanced Magnetic Resonance Imaging (MEMRI) to monitor brain activity. They found that the reward and addiction centers in the brain recorded the most activity. But the food intake, sleep, activity and motion areas also were stimulated significantly differently by eating the potato chips.

“By contrast, significant differences in the brain activity comparing the standard chow and the fat carbohydrate group only appeared to a minor degree and matched only partly with the significant differences in the brain activities of the standard chow and potato chips group.”

Dr Hoch said: “since chips and other foods affect the reward center in the brain, an explanation of why some people do not like snacks is that possibly, the extent to which the brain reward system is activated in different individuals can vary depending on individual taste preferences.”

“In some cases maybe the reward signal from the food is not strong enough to overrule the individual taste. And some people may simply have more willpower than others in choosing not to eat large quantities of snacks.”

“If scientists can pinpoint the molecular triggers in snacks that stimulate the reward center in the brain, it may be possible to develop drugs or nutrients to add to foods that will help block this attraction to snacks and sweets.”

The next project for the team is to identify these triggers. MRI studies with humans are on the research agenda for the FAU Erlangen-Nuremberg group.

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Bibliographic information: Tobias Hoch et al. Everyday desire: Influence of snack food on whole brain activity patterns. 245th ACS National Meeting & Exposition, New Orleans, Louisiana; April 11, 2013