Daijiworld Media Network - New Delhi

New Delhi, Oct 22: Regular cardio exercise like running may help counteract the negative effects of junk food on mental health, according to a new animal study by researchers at University College Cork (UCC), Ireland.

The study, published in the journal Brain Medicine, sheds light on the metabolic mechanisms through which physical activity can buffer mood-related changes caused by a Western-style diet rich in sugar and fat.

Researchers found that voluntary running reduced depression-like behaviours in rats fed a high-fat, high-sugar "cafeteria" diet — behaviours often linked to poor diet quality and altered gut health.

“These findings provide crucial insights into how lifestyle interventions might be optimised to support mental health in an era of widespread ultra-processed food consumption,” said Professor Yvonne Nolan, lead author of the study.

The Study: Fast Food, Fast Wheels

For seven and a half weeks, adult male rats were divided into groups — some fed standard chow, others given access to a rotating menu of calorie-dense, ultra-processed foods. Half of each group was also given access to running wheels.

The results showed that running had a clear antidepressant-like effect, particularly in rats on the poor-quality diet. While junk food alone didn’t significantly impair memory or learning, rats that exercised displayed modest improvements in spatial navigation and reduced anxiety-like behaviours, regardless of what they ate.

Gut-Brain Connection

One of the study’s key insights was the discovery that the cafeteria diet significantly disrupted the gut metabolome, altering 100 out of 175 measured metabolites in sedentary animals.

Exercise helped to partially restore key mood-related metabolites such as:

• Anserine
• Indole-3-carboxylate
• Deoxyinosine

These metabolites have previously been linked to mental well-being and brain function, reinforcing the idea that the gut-brain axis plays a vital role in mood regulation.

Implications for Human Health

While this was an animal study, the findings suggest that even in the context of poor nutrition, regular aerobic activity may offer protective effects against mood disorders. However, the authors caution that exercise alone may not fully compensate for a poor diet when it comes to broader brain health and neuroplasticity.

“Achieving the full benefits of brain resilience likely requires attention to both nutrition and physical activity,” the researchers concluded.

As junk food continues to dominate global diets, the study highlights the importance of lifestyle balance — and suggests that getting on your feet could be a simple, effective first step toward better mental health.