For anyone who's ever tried to kick a junk food habit, science has some encouraging news. new study V Brain medicineA study in Ireland found that regular exercise can counteract the depressive effects of a Western-style cafeteria diet high in fat and sugar, at least in rats.
The team found that voluntary running reversed mood-related changes associated with poor diet through changes in gut metabolites and hormones that connect the body and brain. According to the authors, exercise appears to protect mood by restoring metabolic balance between the gut and brain.
“Exercise has an antidepressant-like effect in the wrong dietary context, which is good news for those who have trouble changing their diet,” said Professor Julio Licinio in a recent report. press release.
When exercise is combined with a junk food diet
To test how food and movement interact, the researchers fed adult male rats either standard chow or an alternating cafeteria diet high in sugar and fat; half of each group had constant access to the running wheels. The intervention lasted 7.5 weeks in four groups with voluntary wheel running.
After less than two months, sedentary rats on a cafeteria diet showed more desperate behavior, higher levels of insulin and leptin, and significant changes in gut chemistry. Exercise curbed weight gain, reduced body fat, and blunted hormonal changes.
The cafeteria diet significantly altered the gut metabolome (100 of 175 measured metabolites in sedentary rats), while exercise altered a small subgroup. The exercise partially restored three metabolites—substances produced during metabolism—that are associated with mood regulation that had been reduced by the cafeteria diet.
Interestingly, running improved overall brain health, but the cafeteria diet blunted one of the biggest benefits of exercise: neurogenesis, or the formation of new neurons in the hippocampus. Rats on the healthier diet experienced a strong neurogenic boost from exercise, while those who ate the unhealthy diet did not, suggesting that the quality of the diet may determine how much the brain benefits from movement.
Read more: It doesn't matter what time you exercise, as long as you get moving
The Gut-Brain Connection
Research shows that exercise helps the brain remain resilient even in the face of poor nutrition by restoring the chemical balance of the gut. Triggers the restoration of key compounds involved in the metabolism of serotonin and amino acids – molecules that help regulate mood and the gut-brain connection.
This recalibration at the gut level may be what allows physical activity to protect mental health, even when eating habits fall short.
Why diet is still important even when you exercise
The study highlights the nuanced relationship between diet, exercise and the brain: While physical activity can boost mood even in the face of poor nutrition, the brain's ability to grow and adapt may still be affected by what we eat. This suggests that exercise alone may not fully restore the neuroplastic benefits that a healthy diet supports.
This opens up new questions about how best to combine lifestyle changes. Future studies will examine whether changes in diet and exercise patterns or longer, sustained programs can enhance these effects. The team also points to several gut-derived compounds as possible biomarkers or therapeutic targets for mood disorders.
Although the experiments were conducted on male rats, the implications extend beyond laboratory studies. As scientists continue to decipher the connection between the gut and the brain, this research adds to a growing body of evidence showing how movement and metabolism work together to shape mental health. For now, even if your diet isn't ideal, getting up and moving remains one of the most powerful tools for keeping your mind and microbiome in balance.
This article does not contain medical advice and should be used for informational purposes only.
Read more: Is 30 minutes of exercise a day enough?
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