The Hunger Hormone That Grows New Brain Cells: Ghrelin and Memory | Research

The takeaway

Ghrelin, the hormone your stomach releases when you're hungry, appears to stimulate the growth of new brain cells in the memory center, potentially explaining why caloric restriction benefits cognitive health.

Hunger → new brain cells
Ghrelin released during food restriction promotes adult hippocampal neurogenesis, providing a biological link between fasting and cognitive function

What the researchers found

Ghrelin, the hunger hormone released by the stomach during food restriction, promotes the growth of new neurons in the hippocampus — the brain's memory center. This review synthesizes accumulating evidence that ghrelin provides a biological link between nutritional status and brain function, specifically by stimulating adult hippocampal neurogenesis.

The review also highlights that disrupted neurogenesis is connected to cognitive decline in aging and neurodegenerative disease, positioning ghrelin as a potential protective factor for brain health when it's properly regulated.

Why it matters

The connection between diet, fasting, and brain health has been observed for decades, but the biological mechanism wasn't clear. This review argues that ghrelin is a key link — when you're in a calorie-restricted state and ghrelin rises, it doesn't just make you hungry; it also stimulates your brain to grow new neurons. This has major implications for understanding why caloric restriction seems to protect against cognitive decline and neurodegeneration.

The numbers in context

Published in Trends in Endocrinology and Metabolism (IF ~12) · Reviews evidence across animal and human studies · Focus: hippocampal neurogenesis and memory

How the study worked

This is a narrative review published in a high-impact endocrinology journal. It synthesizes evidence from animal studies, cellular research, and clinical observations to build the case for ghrelin as a regulator of adult neurogenesis and cognitive function.

Who was studied

Not applicable (review of animal and human studies)

What this study cannot tell us

As a review, no new experimental data is presented. Much of the evidence for ghrelin's neurogenic effects comes from animal models, and direct evidence of ghrelin-stimulated neurogenesis in humans remains limited. The review may emphasize positive findings over null or contradictory results.

How to read the evidence

This is a review article in a high-impact journal (Trends in Endocrinology and Metabolism) that synthesizes evidence from multiple study types. It does not present new data but provides a comprehensive framework for understanding ghrelin's neurogenic role.

When this study was published

Published in 2019, this review captures a relatively mature body of evidence on ghrelin and neurogenesis. The field has continued to develop, particularly with growing interest in metabolic-neurological connections and intermittent fasting research.

The bigger picture

This review sits at the intersection of metabolism and neuroscience — two fields increasingly recognized as deeply connected. The idea that a gut hormone can directly influence brain cell growth helps explain observations from intermittent fasting and caloric restriction research, where cognitive benefits have been noted. It also opens the door to using ghrelin-based therapies for neurodegenerative conditions, though that remains speculative.

Questions still open

Could ghrelin receptor agonists like MK-677 or GHRP-6 stimulate neurogenesis in humans as a treatment for cognitive decline?
Does the neurogenic benefit of ghrelin explain some of the cognitive improvements seen with intermittent fasting?
At what point does chronic ghrelin elevation (as in prolonged starvation) become harmful rather than beneficial for the brain?

Common questions

How does ghrelin help grow new brain cells?

Ghrelin is released by the stomach when you haven't eaten, and it crosses into the brain where it acts on receptors in the hippocampus — the memory center. There, it stimulates the formation of new neurons (neurogenesis), which are important for learning and memory. This may be one reason why caloric restriction appears to protect cognitive function.

Does this mean fasting is good for your brain?

The evidence reviewed here suggests that the ghrelin surge during fasting promotes neurogenesis, which could benefit memory and cognitive function. However, most direct evidence comes from animal studies, and the optimal amount and type of fasting for brain health in humans is still being researched. Prolonged starvation would likely have different effects than moderate caloric restriction.

Read the original research

Ghrelin-Mediated Hippocampal Neurogenesis: Implications for Health and Disease.

Trends in endocrinology and metabolism: TEM, 30(11), 844-859

View on PubMed ↗Publisher’s paper ↗

Citation

Buntwal, Luke; Sassi, Martina; Morgan, Alwena H; Andrews, Zane B; Davies, Jeffrey S. (2019). Ghrelin-Mediated Hippocampal Neurogenesis: Implications for Health and Disease.. Trends in endocrinology and metabolism: TEM, 30(11), 844-859. https://doi.org/10.1016/j.tem.2019.07.001