Between the ads we see on televisions and the smells that come from fast food restaurants, we are conditioned to crave unhealthy foods. When you are used to eating unhealthy, swapping a salad for that burger and fries can be hard to do. Imagine if we could train our brains to love healthy foods?

Researchers from Tufts based in Massachusetts General Hospital wondered if we ate healthy, low-calories foods habitually, if we would be able to condition our brains to eventually favor them.

Published in the journal of Nutrition & Diabetes, the researchers found that despite popular belief that addiction to sugar, fat and salty foods is hard to unwire in the brain, we can actually train our brain to prefer and actually like healthy food.

"We don't start out in life loving French fries and hating, for example, whole wheat pasta," says Susan B. Roberts, director of the Energy Metabolism Laboratory at the USDA Human Nutrition Research Centre on Ageing at Tufts University.

Roberts and the researchers analyzed 13 overweight and obese men and women in a six-month study and found that a reward system can make us enjoy low-calorie foods.

Eight of the participants entered a weight loss program through Tufts University. The remaining five were used as the control group. At the beginning and the end of the six month program, researchers used MRIs to analyze the reward center of the brain that is linked with addiction and learning.

Those who were part of the weight loss program that ate healthy foods habitually increased their brain sensitivity to healthy foods and made eating the foods enjoyable.

"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 food, the combined effects of which are probably critical for sustainable weight control," says Sai Krupa Das, PhD, co-author and scientist in the Energy Metabolism Laboratory at USDA.

The study was aimed to explain that "it is possible to shift preferences from unhealthy food to healthy food without surgery."

Researchers found that the participants who changed their behavior and were educated about eating high-fiber foods -- which ward off hunger longer, were far more successful when losing weight.

"We are very encouraged that, the weight loss program appears to change what foods are tempting to people," says Roberts.

Research is being continued on healthy eating habits and our biology.