Junk food diet has a demonstrated impact on the preference of healthy and novel foods. A study published in the Frontiers in Psychology journal explained how excessive consumption of junk food can change behavior, weaken self-control and lead to overeating and obesity.
The World Health Organization estimates that over 10% of the world’s adult population is obese and is a public health risk causing the death of at least 2.8 million people each year as a result of being overweight or obesity.
The research taught young male rats to associate different sound cues with a flavor of sugar water including cherry and grape. Healthy rats, raised on a healthy diet, stopped responding to cues linked to a flavor in which they have recently overindulged. After 2 weeks on a diet that included daily access to cafeteria foods, including pie, dumplings, cookies and cake the rats changed drastically in behavior with their weight increasing by 10%. The rats became indifferent in their food choices, focusing on the junk food diet and had lost their natural preference for novelty.
The scientist attribute the change in behavior to a lasting change in the reward circuit of the rats’ brain including the orbitofrontal cortex, the area responsible for decision-making. As the brain circuitry is similar in all mammals these results may have implications for people’s ability to limit their intake of certain kinds of foods.
“The interesting thing about this finding is that if the same thing happens in humans, eating junk food may change our responses to signals associated with food rewards,” said UNSW Professor Morris. “It’s like you’ve just had ice cream for lunch, yet you still go and eat more when you hear the ice cream van come by.”
“As the global obesity epidemic intensifies, advertisements may have a greater effect on people who are overweight and make snacks like chocolate bars harder to resist,” said Dr Amy Reichelt, lead author of the paper and UNSWpostdoctoral associate.
Amy C. Reichelt, Margaret J. Morris, R. F. Westbrook. Cafeteria diet impairs expression of sensory-specific satiety and stimulus-outcome learning. Frontiers in Psychology, 2014; 5 DOI: 10.3389/fpsyg.2014.00852