New research suggests that strategic periods without food might do more than help you lose weight—they could literally reprogram your cells to age more slowly and even reverse existing damage.

A 2019 study published in Cell Reports found that fasting triggers a metabolic switch that can increase lifespan by 50% in animal models.

The secret lies in a process called autophagy—your body’s cellular cleanup crew that kicks into hyperdrive when you stop eating.

When you fast, your cells begin removing damaged components and recycling them for energy. This housekeeping mechanism, which slows dramatically as we age, gets a dramatic boost during fasting periods.

Dr. Mark Mattson, former Chief of the Laboratory of Neurosciences at the National Institute on Aging, explains: “Fasting creates mild stress that strengthens cellular defenses against molecular damage and disease.”

The Science Behind Fasting’s Age-Reversing Power

Aging happens when our cells gradually lose their ability to repair themselves. DNA becomes damaged, mitochondria (your cellular power plants) become less efficient, and harmful proteins accumulate.

Fasting appears to directly impact these aging mechanisms through multiple pathways:

1. It reduces insulin and glucose levels, two key drivers of aging
2. It triggers autophagy, removing damaged cellular components
3. It decreases inflammation, a major contributor to age-related diseases
4. It increases production of brain-derived neurotrophic factor (BDNF), promoting brain health
5. It improves mitochondrial function, boosting cellular energy

Dr. Satchin Panda of the Salk Institute explains: “When we fast, we essentially flip a regenerative switch in our bodies.”

In a groundbreaking study from the University of Southern California, researchers found that fasting for just three days could completely regenerate the immune system, even in elderly patients. The study showed that prolonged fasting forces the body to use stores of glucose and fat, but also breaks down a significant portion of white blood cells.

During this process, stem cells awaken and start producing new, healthier immune cells.

“When you starve, the system tries to save energy, and one of the things it does is recycle a lot of the immune cells that are not needed,” explained Dr. Valter Longo, who led the study.

Not Your Grandmother’s Weight Loss Plan

But today’s scientific fasting regimens look nothing like historical starvation diets or religious practices.

Most promising anti-aging protocols involve intermittent fasting, time-restricted eating, or fasting-mimicking diets rather than extended water-only fasts. These approaches provide the metabolic benefits of fasting without extreme deprivation.

The most common methods include:

• 16:8 Method: Eating during an 8-hour window each day (for example, 11am to 7pm)
• 5:2 Protocol: Eating normally five days per week, reducing calories to 500-600 on two non-consecutive days
• Fasting-Mimicking Diet: Following a specialized low-calorie, low-protein, high-fat diet for 5 days monthly

What’s remarkable is how quickly these protocols can produce measurable biological effects. A study published in the New England Journal of Medicine found that after just 24 hours of fasting, your cells dramatically increase their autophagy rates, while human growth hormone levels surge by over 1,300%, promoting tissue repair and muscle maintenance.

Have We Been Wrong About Aging All Along?

Here’s something that might surprise you: constant eating may be one of the worst things we do for longevity.

For decades, nutritionists emphasized the importance of regular meals and snacks to “keep your metabolism going.” The food industry happily promoted this message—after all, more eating means more food sales.

But what if this conventional wisdom is completely backward?

Our bodies didn’t evolve with constant access to food. For most of human history, periods without food were normal and expected. Our ancient ancestors experienced regular intervals between successful hunts or harvests.

Dr. Jason Fung, author of “The Complete Guide to Fasting,” argues: “We evolved in environments where food was scarce and activity was abundant. The human body is perfectly adapted for intermittent fasting.”

This perspective represents a fundamental shift in how we think about nutrition and longevity. Rather than seeing regular meals as essential, emerging science suggests that strategic food avoidance may be the key to extending healthy lifespan.

When researchers at the Buck Institute for Research on Aging compared various interventions, they found that fasting was more effective at extending lifespan than any single drug or supplement tested.

“Fasting is one of the most potent interventions we have to delay aging,” said Dr. Eric Verdin, President and CEO of the Buck Institute.

Even more striking is how fasting uniquely addresses multiple hallmarks of aging simultaneously—something no single medication has achieved. From cellular senescence to genomic instability, strategic calorie restriction impacts virtually every known aging pathway.

Not Just Longer Life, But Better Life

Elizabeth Blackburn, who won the Nobel Prize for her work on telomeres—protective caps on our chromosomes that shrink as we age—found that fasting can help maintain telomere length, potentially extending cellular lifespan.

But the benefits extend far beyond adding years to life. Quality of those years matters tremendously.

Fasting appears particularly beneficial for brain health. Neuroscientist Mark Mattson has published research showing that intermittent fasting enhances cognitive performance and may protect against Alzheimer’s and Parkinson’s diseases.

“Fasting challenges brain cells and triggers adaptive stress responses that help them cope with disease,” Mattson explains. “The cells of people who fast regularly appear biochemically younger than their chronological age.”

This means sharper thinking, better memory, and more stable mood—even in advanced age.

When researchers at the University of Toronto studied the effects of intermittent fasting on cognitive function, they found that fasting increased production of a protein called brain-derived neurotrophic factor (BDNF) by 50-400%. BDNF acts like fertilizer for brain cells, stimulating the growth of new neurons and strengthening existing ones.

These brain benefits don’t just appear in labs. Many regular practitioners of intermittent fasting report improved mental clarity, focus, and energy.

“The first week was tough,” admits Richard Overton, a 78-year-old who began practicing time-restricted eating two years ago. “But now I have more energy than I did twenty years ago. My doctor just told me I have the biomarkers of someone in their 50s.”

The Downsides and Caveats

Fasting isn’t without potential drawbacks. Some people experience hunger, irritability, reduced concentration, or headaches, especially when first adapting to fasting protocols.

“Fasting is not appropriate for everyone,” cautions Dr. Rhonda Patrick, a biomedical scientist who studies aging. “Pregnant women, people with diabetes, and those with a history of eating disorders should consult healthcare providers before attempting any fasting regimen.”

Even for healthy individuals, extreme approaches can be counterproductive. Extended water-only fasts may cause muscle loss, nutrient deficiencies, and metabolic slowdown if not properly managed.

This is why researchers increasingly favor more moderate approaches like time-restricted eating or the fasting-mimicking diet developed by Dr. Longo, which provides carefully formulated nutrition that provides benefits of fasting without complete food deprivation.

“The goal isn’t suffering,” explains Longo. “It’s triggering specific biological responses that promote regeneration and longevity.”

Another important consideration: fasting works best as part of a comprehensive approach to healthy aging that includes quality nutrition, regular physical activity, stress management, and adequate sleep.

Making Fasting Work for You

Despite these caveats, the evidence suggests that most adults could benefit from some form of fasting. But which approach is best?

“The ideal fasting protocol varies by individual,” says Dr. Peter Attia, longevity expert and author of “Outlive.” “Factors like age, health status, medications, lifestyle, and personal preferences all matter.”

For beginners, doctors often recommend starting with a gentle approach:

1. Gradually extend overnight fasting to 12 hours, then 14, then 16
2. Choose an eating window that fits your lifestyle and preferences
3. Stay hydrated with water, black coffee, or unsweetened tea during fasting periods
4. Emphasize nutrient-dense foods during eating windows
5. Monitor how you feel and adjust accordingly

Dr. Satchin Panda, whose research pioneered time-restricted eating, suggests another approach: “Try to consume all your meals within a 10-12 hour window, and gradually narrow that window if it feels comfortable.”

For those seeking more dramatic results, supervised programs like ProLon (a commercial fasting-mimicking diet) provide structured five-day protocols that can be followed monthly or quarterly.

From Lab Discovery to Lifestyle Revolution

What makes the science of fasting particularly exciting is how accessible it is. Unlike expensive medications or treatments, fasting costs nothing and requires no special equipment.

“This is perhaps the most democratic health intervention we have,” notes Dr. David Sinclair, Professor of Genetics at Harvard Medical School and author of “Lifespan.”

The research has spawned a cultural movement. Online communities dedicated to intermittent fasting have millions of members. Silicon Valley executives and Hollywood celebrities have embraced various fasting protocols, helping popularize what was once considered a fringe practice.

But the true promise lies in fasting’s potential to transform how we age as a society. As our population grows older, maintaining health and independence in later years becomes increasingly important.

Traditional medical approaches focus on treating diseases after they develop. Fasting represents a fundamentally different paradigm—preventing age-related decline before it starts and potentially reversing damage that’s already occurred.

“We’re moving from a disease-centric model of medicine to a health-centric model,” explains Dr. Kara Fitzgerald, whose clinical research shows that fasting combined with other lifestyle interventions can reduce biological age by over three years in just eight weeks.

A New Frontier in Aging Research

As promising as the current research is, we’re still in the early stages of understanding fasting’s full potential.

Major research institutions are now investing heavily in this area. The National Institute on Aging has funded multiple clinical trials examining fasting’s effects on cardiovascular health, cancer risk, and cognitive function in humans.

Meanwhile, biotechnology companies are developing “fasting mimetics”—compounds that trigger the same biological pathways as fasting without requiring actual calorie restriction. These include compounds like resveratrol, spermidine, and rapamycin.

“The goal is to capture fasting’s benefits in more targeted, convenient forms,” explains Dr. David Sabatini, whose lab at MIT studies the molecular mechanisms through which fasting extends lifespan.

But scientists caution that pills are unlikely to fully replicate the comprehensive benefits of actual fasting. The complexity of fasting’s effects—involving multiple tissues, hormones, and cellular mechanisms—makes it difficult to capture in a single intervention.

The Future of Aging

Could strategic fasting help humans routinely live healthy, vibrant lives well past 100? Many researchers believe it’s possible.

“We’re not talking about prolonging the period of frailty and dependence,” clarifies Dr. Nir Barzilai, director of the Institute for Aging Research at Albert Einstein College of Medicine. “We’re talking about extending the healthy, productive years.”

The implications extend beyond individual health. If large portions of the population maintained their physical and cognitive function decades longer than currently expected, it would transform retirement systems, healthcare delivery, and cultural attitudes toward aging.

For now, the science strongly suggests that periodic fasting deserves consideration as part of any longevity strategy. As research advances, protocols will likely become more personalized and precise, tailored to individual genetics, health status, and goals.

“We’re moving toward a world where aging itself becomes a treatable condition,” says Dr. Sinclair. “And fasting may be one of our most powerful tools in that endeavor.”

The ancient practice of temporarily abstaining from food, guided by cutting-edge science, could help redefine what it means to grow old in the 21st century.

References

Longo, V.D., & Mattson, M.P. (2014). Fasting: Molecular mechanisms and clinical applications. Cell Metabolism, 19(2), 181-192.

de Cabo, R., & Mattson, M.P. (2019). Effects of intermittent fasting on health, aging, and disease. New England Journal of Medicine, 381(26), 2541-2551.

Mattson, M.P., Moehl, K., Ghena, N., Schmaedick, M., & Cheng, A. (2018). Intermittent metabolic switching, neuroplasticity and brain health. Nature Reviews Neuroscience, 19(2), 63-80.

Brandhorst, S., Choi, I.Y., Wei, M., Cheng, C.W., Sedrakyan, S., Navarrete, G., … & Longo, V.D. (2015). A periodic diet that mimics fasting promotes multi-system regeneration, enhanced cognitive performance, and healthspan. Cell Metabolism, 22(1), 86-99.

Anton, S.D., Moehl, K., Donahoo, W.T., Marosi, K., Lee, S.A., Mainous, A.G., … & Mattson, M.P. (2018). Flipping the metabolic switch: Understanding and applying the health benefits of fasting. Obesity, 26(2), 254-268.

Wei, M., Brandhorst, S., Shelehchi, M., Mirzaei, H., Cheng, C.W., Budniak, J., … & Longo, V.D. (2017). Fasting-mimicking diet and markers/risk factors for aging, diabetes, cancer, and cardiovascular disease. Science Translational Medicine, 9(377).

Cheng, C.W., Adams, G.B., Perin, L., Wei, M., Zhou, X., Lam, B.S., … & Longo, V.D. (2014). Prolonged fasting reduces IGF-1/PKA to promote hematopoietic-stem-cell-based regeneration and reverse immunosuppression. Cell Stem Cell, 14(6), 810-823.

Fitzgerald, K.N., Hodges, R., Hanes, D., Stack, E., Cheishvili, D., Szyf, M., … & Helfgott, S.M. (2021). Potential reversal of epigenetic age using a diet and lifestyle intervention: a pilot randomized clinical trial. Aging, 13(7), 9419-9432.

Panda, S. (2016). Circadian physiology of metabolism. Science, 354(6315), 1008-1015.

Sinclair, D.A., & LaPlante, M.D. (2019). Lifespan: Why We Age―and Why We Don’t Have To. Atria Books.