Brain scans suggest people can learn to like healthy foods

Date: Sep-02-2014A small study using brain scans suggests the addictive power of unhealthy, high-

calorie food can be reduced and the brain retrained to prefer healthy, lower

calorie foods. Participants who followed a 6-month behavioral weight-loss program showed

significant changes in the way the reward centers in their brains responded to the two types of

food.

The study team, including researchers from Harvard Medical School and Tufts University,

both in Boston, MA, reports the findings in the journal Nutrition & Diabetes.

Senior author Susan B. Roberts, who among other posts holds a professorship at Tufts'

Friedman School of Nutrition Science and Policy, says:

"We don't start out in life loving French fries and hating, for example, whole wheat pasta.

This conditioning happens over time in response to eating - repeatedly! - what is out there in

the toxic food environment."

Something scientists are uncertain about is when people become addicted to unhealthy foods,

does this mean the brain circuits that reinforce the addiction are fixed for good, or can they

be reversed? If they are fixed then people trying hard to lose excess weight face a lifetime of

battling temptation and ignoring food cravings.

Study suggests the brain is 'plastic' and addiction to unhealthy food can be reversed

Comparing the scans taken before and after the program, the team saw a significant shift in reward center activity away from high-calorie toward low-calorie foods in the group that followed the program.

But this study - although small and still to be confirmed by longer-term research with much

larger groups - offers hope. It suggests that the brain is "plastic" when it comes to food

addiction: the circuits can be reversed with training.

Prof. Roberts and colleagues studied the reward systems in the brains of 13 overweight and

obese men and women. Eight of the volunteers were enrolled in a new 6-month weight-loss

program designed by Tufts University, and the other five were not - they were the control

group.

All participants had brain scans at the beginning and end of the program. From the functional

magnetic resonance imaging (fMRI) scans, which were conducted as the participants were shown

images of high- and low-calorie foods, the researchers could observe activity in the reward

centers in the brain, which are associated with learning and addiction.

By the end of the 6-month program, compared to controls (who on average gained over 2 kg),

the program followers achieved significant weight loss (on average they lost over 6 kg).

The scan results showed that compared to the controls, the group that followed the weight-loss program showed increased reward center activity in response to seeing images of low-calorie

foods at the end of the program, and decreased activity in response to high-calorie foods.

(Strictly speaking, the term "low-calorie" is a shorthand for the types of food recommended by

the weight-loss program and "high-calorie" is shorthand for the types of food the program

discourages.)

And when the team compared the scans taken before and after the program, they saw a

significant shift in reward center activity away from high-calorie toward low-calorie foods in

the group that followed the program.

These changes suggest the participants were experiencing more reward and enjoyment of

healthier food cues at the end of the program than they were at the start.

Reversing addiction to unhealthy food plus increasing liking for healthy food is the

key

The weight-loss program is designed to change how people react to different foods. The

team suggests it is the combination of reversing addiction to unhealthy food and increasing the

liking for healthy food that is important for sustained weight loss. As first author Dr. Thilo

Deckersbach, a psychologist at Massachusetts General Hospital in Boston, explains:

"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."

"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," he adds.

The team believes this is the first study to show the shift in food preferences in this

way.

Speculating on which aspects of the weight-loss program were important, they say it was

probably the combination of learning how to change behavior and the high-fiber, low glycemic

menu plans that the participants followed.

Prof. Roberts points out there is still a lot more research needed to confirm these findings,

including studies involving more participants, with long-term follow-up, and also looking at

other areas of the brain.

"But we are very encouraged that the weight-loss program appears to change what foods are

tempting to people," she adds.

Funds for the study came from the US Department of Agriculture and the Jean Mayer USDA Human

Nutrition Research Center on Aging at Tufts University.

Prof. Roberts has a financial stake in iDiet, an online weight-loss program similar to the

one used in the study.

In April 2014, in the first study of its kind, scientists reported how they used MRI to identify brown fat in a living adult. Writing in The

Journal of Clinical Endocrinology and Metabolism, they explained how the findings could

lead to new treatments for obesity and diabetes.

Written by Catharine Paddock PhD

View all articles written by Catharine, or follow her on:

Courtesy: Medical News Today Note: Any medical information available in this news section is not intended as a substitute for informed medical advice and you should not take any action before consulting with a health care professional.