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We’ve long known that exercise keeps the body fit, but compelling new research suggests it may also be a vital key to preserving brain health — even when the brain is under energy stress.
A new study from the University of Missouri, conducted by researchers Taylor Kelty and Dr. R. Scott Rector, found that physical activity could help maintain mental sharpness even when the brain lacks ketones, one of its critical energy sources.
The Brain’s Backup Fuel: Ketones
Under normal circumstances, the brain uses glucose as its primary energy source. However, when glucose runs low — such as during fasting or intense physical activity — the liver produces ketones, which provide an essential backup fuel. These ketone molecules are known to support learning, memory, and cognitive performance.
But what happens when this ketone production is impaired? That’s the question Kelty and Rector set out to explore.
Testing Cognitive Function Without Ketones
In the study, the researchers restricted the liver’s ability to produce ketones and observed a predictable result: reduced cognitive function and memory impairments. This demonstrated just how critical ketones are for maintaining brain performance under stress.
However, a surprising discovery soon followed.
Exercise Still Boosted Brain Health
Even with impaired ketone production, the researchers found that exercise significantly improved cognitive outcomes. This suggests that physical activity triggers alternative mechanisms in the brain that can support memory and function — even in the absence of optimal fuel.
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“Going into the study, we thought that with fewer ketones and the cognitive impairments that causes, exercise may not be able to overcome that impairment,” said Taylor Kelty, a postdoctoral fellow working under Rector.
“But it seems like exercise is so powerful that there are other mechanisms going on in the brain that allow it to circumvent those impairments and still receive the benefits from exercise,” he added.
A Hopeful Sign for Alzheimer’s and Aging Brains
The study’s implications are particularly important as the number of Americans diagnosed with Alzheimer’s disease is expected to more than double by 2060. With no known cure, scientists are increasingly focused on prevention — and lifestyle factors like exercise may play a much greater role than previously believed.
Dr. Rector, director of the Roy Blunt NextGen Precision Health Building, emphasized the potential impact: “This adds to a growing body of evidence suggesting that regular exercise is not just good for physical health — it could be one of the most effective strategies we have to protect the brain as we age.”
Beyond Ketones: The Brain’s Resilience
Though the exact pathways through which exercise compensates for ketone deficiency remain unclear, this study highlights the brain’s resilience and adaptability. It also provides strong scientific support for physical activity as a preventive tool against cognitive decline, even in metabolically compromised conditions.
As further research is conducted, scientists hope to pinpoint the biological mechanisms behind these findings — and possibly unlock new therapeutic strategies for brain health.
