Modern diets rich in processed foods are known to increase the risk of obesity, diabetes, and heart disease.
What is less known is their potential link to depression and anxiety.
Researchers at University College Cork recently explored this connection in a study on rats fed a typical Western-style diet filled with high-fat and high-sugar foods.
Over several weeks, these rats developed signs of depressive and anxious behavior.
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The study also showed that this type of diet disrupted key hormones such as insulin and leptin, which play a role in metabolism and mood.
It even affected the gut microbiome, the community of bacteria in the digestive system, altering how certain brain-related chemicals were produced.
Exercise makes a difference
To find out whether physical activity could help, the researchers gave some rats access to running wheels.
Those that exercised showed fewer symptoms of depression and anxiety compared to sedentary rats on the same unhealthy diet.
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Exercise appeared to normalize insulin and leptin levels and helped preserve several beneficial compounds produced by gut bacteria.
These compounds are linked to brain function and emotional balance.
However, the researchers noticed that not all problems caused by the diet were reversed.
For example, while exercise improved mood-related behavior, it did not fully restore normal hormone levels or promote the same level of new brain cell growth seen in rats with a healthy diet.
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Exercise is best for mental health
According to Professor Yvonne Nolan, who led the study, exercise offers a partial shield against the mental health effects of an unhealthy diet.
Yet it cannot undo all the biological damage caused by poor eating habits.
Experts agree that while physical activity can improve mood and help manage stress, it works best when paired with balanced nutrition.
As psychiatrist Dr. Gia Merlo noted, exercise might be the first step toward better mental well-being, helping people gain the motivation to make healthier dietary choices later on.
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This article is based on information from Medical News Today.
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