Junk Food & Brain Science

A recent study involving rats that consumed a diet of high-fat, calorie-rich foods may help scientists explain how junk food also affects the human brain.

Study Overview

• Rats on a diet high in calories and fats were found to develop compulsive binge eating habits, according to the study conducted by Paul Johnson of the Scripps Research Institute in Florida. The rats also developed addiction-like tendencies that caused them to continue to overeat even when they had to endure negative consequences for doing so.

Why This Happens

• The area responsible for receiving the sensation of pleasant feelings or feelings of pleasure in the rats' brains became less sensitive over the course of the study. This caused the rats to need more and more food to feel the same amount of pleasure they were initially feeling as the result of eating junk food.

Resulting Diet Choices

• The study also revealed that as the rats became more used to their diet of junk food and the pleasure centers of their brains became less sensitive to sensation, the rats became less likely to eat a nutritious, healthy diet. When the rats were deprived of junk food and given only healthy food to eat, they chose to eat nothing at all rather than eat the nutritious food.

Addictive Properties

• The rats in the junk food study lost control of their eating habits much in the same way heroin addicts lose control of their intake of the drug, needing more and more just to feel that initial sensation of pleasure. The study also revealed that when the rats eating junk food were given negative consequences for overeating, they disregarded the unpleasantness of the consequences and continued to eat, whereas rats that had not been eating junk food were very much affected by the negative consequences.

Implications for Humans

• Scientists speculate that this study may help researchers understand how junk food affects the pleasure sensors in the brains of humans. The junk-food diets fed to the rats in the study consisted of many of the same high-calorie foods millions of Americans consume every day, such as cheesecake, bacon and sausage. By studying the effects of junk food in the brains of rats, scientists hope to make advancements in human brain science.