It may be possible to train the brain to
prefer healthy low-calorie foods over unhealthy higher-calorie foods, according
to new research by scientists at the Jean Mayer USDA Human Nutrition Research
Center on Aging (USDA HNRCA) at Tufts University and at Massachusetts General
Hospital. Published online today in the journal Nutrition & Diabetes,
a brain scan study in adult men and women suggests that it is possible to
reverse the addictive power of unhealthy food while also increasing preference
for healthy foods.
"We don't
start out in life loving French fries and hating, for example, whole wheat
pasta," said senior and co-corresponding author Susan B. Roberts, Ph.D.,
director of the Energy Metabolism Laboratory at the USDA HNRCA, who is also a
professor at the Friedman School of Nutrition Science and Policy at Tufts
University and an adjunct professor of psychiatry at Tufts University School of
Medicine. "This conditioning happens over time in response to eating –
repeatedly! - what is out there in the toxic food environment."
Scientists have
suspected that, once unhealthy food addiction circuits are established, they
may be hard or impossible to reverse, subjecting people who have gained weight
to a lifetime of unhealthy food cravings and temptation. To find out whether the
brain can be re-trained to support healthy food choices, Roberts and colleagues
studied the reward system in thirteen overweight and obese men and women, eight
of whom were participants in a new weight loss program designed by Tufts
University researchers and five who were in a control group and were not
enrolled in the program.
Both groups
underwent magnetic resonance imaging (MRI) brain scans at the beginning and end
of a six-month period. Among those who participated in the weight loss program,
the brain scans revealed changes in areas of the brain reward center associated
with learning and addiction. After six months, this area had increased
sensitivity to healthy, lower-calorie foods, indicating an increased reward and
enjoyment of healthier food cues. The area also showed decreased sensitivity to
the unhealthy higher-calorie foods.
"The weight
loss program is specifically designed to change how people react to different
foods, and our study shows those who participated in it had an increased desire
for healthier foods along with a decreased preference for unhealthy foods, the
combined effects of which are probably critical for sustainable weight
control," said co-author Sai Krupa Das, Ph.D., a scientist in the Energy
Metabolism Laboratory at the USDA HNRCA and an assistant professor at the
Friedman School. "To the best of our knowledge this is the first
demonstration of this important switch." The authors hypothesize that
several features of the weight loss program were important, including behavior
change education and high-fiber, low glycemic menu plans.
"Although
other studies have shown that surgical procedures like gastric bypass surgery
can decrease how much people enjoy food generally, this is not very
satisfactory because it takes away food enjoyment generally rather than making
healthier foods more appealing," said first author and co-corresponding
author Thilo Deckersbach, Ph.D., a psychologist at Massachusetts General
Hospital. "We show here that it is possible to shift preferences from
unhealthy food to healthy food without surgery, and that MRI is an important
technique for exploring the brain's role in food cues."
"There is
much more research to be done here, involving many more participants, long-term
follow-up and investigating more areas of the brain," Roberts added.
"But we are very encouraged that, the weight loss program appears to
change what foods are tempting to people."
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