The first is that a diet full of burgers, fries, sweets and pies could re-wire your brain and kill our appetite for healthy foods. Scientists in Australia discovered that living on junk food not only makes rats fat, but also suppresses their desires to eat a balanced diet. Those scientists believe their findings help explain how excessive consumption of unhealthy foods can change a persons behavior, weaken self-control and lead to overeating and obesity.
The team from the University of New South Wales taught young rats to associate each of two different sound cues with a particular flavor of sugar water - cherry and grape. Rats raised on a healthy diet stopped responding to cues linked to a flavor in which they had recently over indulged. This natural mechanism, widespread in animals, protects against overeating and helps promote a healthy, balanced diet.
However, after 2 weeks eating a daily diet rich in cafeteria foods including pie, dumplings, cookies and cake - with 150% more calories, the rats' weight increased by 10%.
The researchers also noted that at the same time their behavior had also changed dramatically. They became indifferent in their food choices and no longer avoided the sound cues advertising the over familiar taste. This lead to the deduction that this indicated the rats had lost their natural preference for healthy foods. The researchers noted that this change lasted for some time after the rats were given a healthy diet.The team concluded that a diet of junk food causes lasting changes in the reward circuit parts of the rats' brains, including the orbital-frontal cortex - an area of the brain responsible for decision making. These findings may have implications for humans' ability to limit their intake of certain kinds of foods, because the brain's reward circuits are similar in all mammals.
However, in The States at the Friedman School of Nutrition Science and Policy at Tufts University, another study has been carried out which has discovered that you can train your brain to prefer healthy foods over unhealthy foods.
"We don't start out in life loving french fries and hating, for example, whole wheat pasta," said author Susan Roberts, "This conditioning happens over time in response to eating - repeatedly, what is out there in the toxic food environment."At Tufts, researchers studied 13 overweight and obese men and women, 8 of whom were participants in a new weight loss program designed by Tufts University researchers and 5 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 6 month period.
The diet they followed was portion-controlled menus and recipe suggestions, with high-satiety menu plans, recipes and tip sheets provided by the researchers.
The menu plans provided approximately 25% energy from protein and fat, and 50% from low-glycemic index carbohydrates and contained 40g of dietary fiber per day.
The dieters also received nineteen 60 minute didactic and support group sessions over the 6 month period. In addition to the group sessions, the participants also received a weekly email from their nutritionist for individual support.
Among those who participated in the weight loss program, the brain scans revealed changes in the areas of the brain reward center associated with learning and addiction. After 6 months, this area had increased sensitivity to healthy, lower calorie foods, indicating an increased reward and enjoyment of healthier food cues.
So, junk food can re-wire your brain to prefer unhealthy food options, but you can also retrain your brain to prefer healthier food options. Now that's good news!
I can help you improve your health. If you would like to make an appointment with me either in person or via Skype, just send me an email to lucycarr@socialnutrition.com
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