Fasting, Brain Health & Longevity
Could fasting help protect the aging brain or contribute to a longer, healthier life?
Researchers are studying whether fasting influences inflammation, brain metabolism, cellular repair, and biological processes associated with aging.
The possibilities are intriguing, but evidence that fasting prevents Alzheimer's disease or extends human lifespan remains limited.
Fasting and the Brain
The brain normally relies heavily on glucose for energy. During longer periods without food, the liver produces ketones, which the brain can also use.
This has attracted interest in Alzheimer's research because impaired glucose metabolism is commonly observed in affected regions of the brain.
Small studies of ketogenic diets and ketone supplements have reported encouraging cognitive findings.
However, providing the brain with an alternative fuel does not necessarily prevent or reverse Alzheimer's disease. Nor do studies of ketogenic diets establish that intermittent fasting produces the same benefits.
Mark Mattson: Fasting and Brain Health
Mark Mattson, PhD, formerly of the National Institute on Aging, has studied how fasting affects brain health.
His research suggests that fasting may activate cellular stress-response pathways that help maintain healthy neurons.
Animal studies have reported improvements in brain resilience and certain measures of cognitive function.
Mattson has also studied brain-derived neurotrophic factor (BDNF), a protein involved in neuronal health and adaptability.
Dale Bredesen and Nick Norwitz: Metabolic Approaches
Dr. Dale Bredesen, developer of the ReCODE protocol, emphasizes insulin sensitivity, ketones, and metabolic health in his approach to Alzheimer's prevention.
His KetoFlex 12/3 program recommends fasting for at least 12 hours overnight and finishing dinner at least three hours before bedtime.
For people carrying the APOE4 gene variant, he often recommends gradually extending the overnight fast to 14–16 hours or longer, depending on individual circumstances.
Dr. Nick Norwitz, a physician and metabolic-health researcher, has explored ketogenic diets, ketones, and their potential applications to neurological health.
Both emphasize the importance of brain energy metabolism, although their approaches differ.
These strategies show promise, although their effectiveness in preventing Alzheimer's disease is still being researched.
For more information, see The Bredesen Approach.
Valter Longo: Fasting and Longevity
Valter Longo, PhD, a researcher at the University of Southern California, has studied fasting, nutrition, and aging.
He developed the fasting-mimicking diet (FMD), a short-term, low-calorie eating program designed to reproduce some metabolic effects of fasting while still providing food.
A 2024 study reported improvements in insulin resistance, liver fat, and biomarkers associated with biological aging.
Participants completing three monthly fasting-mimicking cycles showed an estimated reduction of approximately 2.5 years in median biological age.
This does not mean participants actually became 2.5 years younger or will live longer. Biological-age estimates are based on biomarkers, not demonstrated increases in lifespan.
Longo also emphasizes the importance of adequate nutrition and avoiding excessive fasting, particularly in older adults.
Does Fasting Increase Longevity?
Calorie restriction and certain fasting approaches have extended lifespan in some animal experiments.
Researchers believe several processes may contribute:
Changes in insulin and IGF-1 signaling
Reduced activity of nutrient-sensing pathways such as mTOR
Improved cellular stress responses
Increased cellular maintenance and recycling
However, animal findings do not necessarily translate to humans.
Whether intermittent fasting extends human lifespan remains unknown. Long-term human studies are difficult to conduct, so researchers must rely largely on animal experiments and indirect measures of aging and health.
What About People Over 70?
For older adults, potential benefits must be balanced against nutritional risks.
Long fasting periods may make it difficult to consume adequate calories and protein.
Loss of muscle mass is particularly concerning because it increases the risk of weakness, falls, and loss of independence.
A modest overnight fast may be more appropriate for some older adults than prolonged fasting.
The Bottom Line
Research by Mattson, Bredesen, Norwitz, Longo, and others suggests that fasting may benefit brain health and healthy aging.
Whether fasting can prevent Alzheimer's disease or extend human lifespan remains uncertain.
For people in their 70s and 80s, potential benefits must be balanced against the importance of preserving muscle strength and maintaining adequate nutrition.
Learn More
Mark Mattson and Rafael de Cabo review fasting's effects on metabolism, brain health, and aging.
Research by Valter Longo and colleagues examining improvements in metabolic health and biological-aging biomarkers.
Explains the fasting and nutritional recommendations included in the ReCODE approach.
Valter Longo — Longevity Institute
Research on fasting-mimicking diets, nutrition, and healthy aging.
Health Curious provides educational information, not individualized medical advice. Older adults, particularly those who are underweight, frail, or taking medications that affect blood glucose, should discuss substantial fasting or dietary changes with their healthcare professional.