Our bodies operate in one of two fundamental states: either building or repairing. This dual mode reflects an ancient evolutionary rhythm shaped by early humans’ cycles of feast and famine. Today, modern science increasingly reveals how intermittent fasting taps into these natural cycles, unlocking profound health benefits and promoting longevity.
The 5:2 Diet and Its Origins
Around three years ago, a caller to my radio show introduced me to the 5:2 intermittent fasting method. The protocol is simple yet powerful: eat normally for five days a week, then reduce calorie intake to no more than 500 calories on two consecutive days, repeating this cycle continuously.
This approach has garnered scientific attention and practical acclaim. Recently, The Washington Post covered new research supporting intermittent fasting’s role in extending lifespan and combating chronic diseases like cancer and diabetes.
mTOR: The Key to Aging and Repair
The mechanism behind these benefits lies partly in the regulation of an enzyme known as mTOR (mechanistic Target Of Rapamycin). According to a pivotal 2013 Nature article, mTOR plays a central role in aging and age-related diseases. Scientists found that inhibiting mTOR in animals, including primates, led to longer lifespans and protection against multiple health issues.
In practical terms, when mTOR is active, our bodies focus on building—converting extra calories to fat and fueling growth and metabolism. When fasting triggers the inhibition of mTOR, the body switches to repair mode.
What Happens During Repair Mode?
Fasting for over a day prompts the body to burn stored fat and activate autophagy—a cellular housekeeping process that dismantles “zombie” or senescent cells. These aged cells no longer function properly but continue to drain resources and energy.
Autophagy recycles these old cells into raw materials for new, healthy cells, optimizing metabolic efficiency and easing the load on our organs. This cellular cleanup contributes not only to improved physical health but also mental clarity and resilience.
Interestingly, consuming more than 500 calories interrupts this repair state, nudging the body back into building mode. This calorie threshold aligns with our evolutionary history when periods of scarcity necessitated a shift toward preservation and regeneration.
Lessons From History and Science
Survivors of extreme starvation, such as those who endured Nazi concentration camps, often live longer than their contemporaries—likely due to the prolonged activation of their bodies’ repair mechanisms during those harsh times.
Recently, Takarudana Mapendembe highlighted extensive research demonstrating intermittent fasting’s benefits: improved insulin sensitivity, weight management, reduced inflammation, enhanced immune function, hormone regulation, better digestion, and lowered heart disease risk.
A Personal Journey Into Fasting
My wife Louise and I have long embraced fasting principles, inspired by Arnold Ehret’s 1910 classic Rational Fasting. Our spiritual beliefs and opposition to war guided us toward vegetarianism, and regular water and juice fasts became part of our lifestyle—even while raising three vegetarian children.
After hearing about the 5:2 diet, we incorporated it and witnessed real improvements in health and well-being. One remarkable experience is the genuine hunger felt after fasting days—a sensation most Americans rarely encounter. This deep hunger makes the first meal afterward not just satisfying but a profound joy.
Surprisingly, rather than feeling fatigued, fasting sharpens the mind. I find my mental clarity and energy soar after two days of restricted calories, a counterintuitive but well-documented effect.
Why This Matters Today
Intermittent fasting offers a scientifically validated, accessible way to tap into our bodies’ natural healing potential. Whether for weight loss, managing diabetes, or enhancing overall longevity, it holds promise beyond conventional diets.
For those interested, The Fast Diet by British scientist Michael Mosley details how modest calorie reduction during fasting days can mirror the benefits of prolonged water fasting, without extreme deprivation.
Final Thoughts
Understanding and harnessing the body’s build-repair cycle connects us to ancient wisdom and cutting-edge science alike. As we navigate modern challenges of chronic disease and lifestyle stress, intermittent fasting stands out as a powerful tool for renewal and vitality.
By embracing these rhythms, we don’t just add years to life but life to our years—nurturing body, mind, and spirit toward their fullest potential.
Reprinted with permission from Thom Hartmann’s The Wisdom School Substack: What It Means To Be Human.
About Thom Hartmann
Thom Hartmann is a New York Times bestselling author of 34 books translated into 17 languages. He is also the nation’s top progressive radio host, psychotherapist, and international relief worker. Subscribe to The Hartmann Report for daily insights on politics, science, and culture.