The scientific secrets underpinning that awful reality about
potato chips — eat one and you're apt to scarf 'em all down — began coming out
of the bag in research presented at the 245th National Meeting & Exposition
of the American Chemical Society, the world's largest scientific society.
Tobias Hoch, Ph.D., who conducted the study, said the
results shed light on the causes of a condition called "hedonic
hyperphagia" that plagues hundreds of millions of people around the world.
"That's the scientific term for 'eating to excess for
pleasure, rather than hunger,'" Hoch said. "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
How the study was
The team at FAU Erlangen-Nuremberg, in Erlangen, Germany,
probed the condition with an ingenious study in which scientists allowed one
group of laboratory rats to feast on potato chips. Another group got bland old
rat chow. Scientists then used high-tech magnetic resonance imaging (MRI)
devices to peer into the rats' brains, seeking differences in activity between
the rats-on-chips and the rats-on-chow.
With recent studies showing that two-thirds of Americans are
obese or overweight, this kind of recreational over-eating continues to be a
major problem, health care officials say.
Among the reasons why people are attracted to these foods,
even on a full stomach, was suspected to be the high ratio of fats and
carbohydrates, which send a pleasing message to the brain, according to the
team. In the study, while rats also were fed the same mixture of fat and
carbohydrates found in the chips, the animals' brains reacted much more
positively to the chips.
"The effect of potato chips on brain activity, as well
as feeding behaviour, can only partially be explained by its fat and
carbohydrate content," explained Tobias Hoch, Ph.D. "There must be
something else in the chips that make them so desirable," he said.
In the study, 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, he said. 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, Hoch said.
Hoch explained that the team mapped the rats' brains using
Manganese-Enhanced Magnetic Resonance Imaging (MEMRI) to monitor brain
activity. They found that the reward and addiction centres 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
"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," he added.
Since chips and other foods affect the reward centre 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,"
according to Hoch. "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, he suggested.
If scientists can pinpoint the molecular triggers in snacks
that stimulate the reward centre 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, he said. The next project for the team, he added, is to
identify these triggers. He added that MRI studies with humans are on the research
agenda for the group.
On the other hand, Hoch said there is no evidence at this
time that there might be a way to add ingredients to healthful, albeit rather
unpopular, foods like Brussels sprouts to affect the rewards centre in the