A new study explains how eating high-calorie, sugary and fatty junk food can alter brain function and behaviour. Researchers found that these diets not only alter brain pathways but also affect the way mice, especially obese mice, seek out food.

Researchers at the University of Michigan in the US found that this discovery could help us better understand obesity and find ways to fight it. With obesity rates rising around the world, it is important to know how high-calorie diets affect our brain.

Previous studies have shown that these diets can alter the brain’s reward centers, such as the nucleus accumbens, which is important for processing pleasure and reinforcing behavior through dopamine secretion.

The aim of this study, published in Neuropharmacology, was to see how changes in the nucleus accumbens differ between obese mice and obesity-resistant mice.

The researchers divided male mice into three groups: those fed standard lab chow, those given junk food, and those given regular chow followed by junk food. The junk food was similar to a high-calorie human diet, including things like chips and cookies.

The mice were tested to see how they respond to food cues and their motivation to seek out food. Obese mice showed less motivation to seek out food when fed junk food, but increased food seeking behavior after being deprived of it. Obesity-resistant mice did not show significant changes after being deprived of junk food.

Brain studies have shown that after junk food deprivation, there was increased CP-AMPR activity in the nucleus accumbens of obese rats, which was associated with input from the medial prefrontal cortex (mPFC).

This discovery helps us understand the neural mechanisms behind these behavioural changes.

Studies show that eating junk food and then stopping it can lead to significant changes in the brain and behaviour, especially in people with obesity. Understanding these changes is important for tackling obesity and finding new treatment targets.

The researchers concluded, “These findings suggest that interactions between an individual’s predisposition to obesity and diet may lead to weight gain and obesity.”