The History of Intermittent Fasting
Starting in the 1930s, studies performed on rats revealed that reduced food intake extended lifespan (McCay, 1934). The studies focused on calorie restriction (CR) rather than intermittent fasting, but they effectively laid the groundwork for later research.
Later, in the 1940s, fasting started gaining attention in medical contexts. For instance, Dr. Ancel Keys’ Minnesota Starvation Experiment (1944–1945) explored the physiological effects of severe calorie restriction, indirectly informing fasting’s metabolic impacts.
Later, in the 1970s and 80s, early intermittent fasting (IF) concepts emerged among niche health communities. Books like Fasting: The Ultimate Diet, by Dr. Allan Cott (1975), popularized fasting for weight loss, though often without robust scientific backing.
In the 2000s, scientific interest in IF grew with an increasing number of studies reporting on its metabolic benefits. Dr. Mark Mattson’s research at the National Institute on Aging showed IF improved insulin sensitivity, brain health, and longevity in animals, sparking wider interest.
Finally, in the 2010s, IF gained mainstream traction through media and books. Dr. Michael Mosley’s 5:2 Diet: Popularized via his 2012 BBC documentary Eat, Fast, and Live Longer and book The Fast Diet (2013), it brought wide-scale attention to IF. The 5:2 method—eating normally for 5 days and restricting to 500–600 calories for 2 days—made IF more accessible. Dr. Jason Fung in his 2016 book The Obesity Code linked IF to insulin regulation and weight loss, boosting its popularity among low-carb and keto communities.
Since then, the term “intermittent fasting” has become a buzzword in fitness and wellness circles.
Social Media and Apps: Platforms like Reddit, YouTube, and X amplified IF’s reach, with influencers sharing protocols like 16/8 and OMAD (One Meal a Day). Apps like Zero and MyFitnessPal introduced fasting trackers, making IF user-friendly.
Since then, many clinical studies have validated IF’s benefits for weight loss, metabolic health, and inflammation reduction. And the rest is history.
The science of fasting
So why does fasting matter, and how does it help us live healthier lives? Think of it this way: our cells are little machines, with lots of moving parts, and much like man-made devices—such as televisions or automobiles—they are subject to wear and tear.
But unlike a mechanical machine, which wears out from friction, heat, and corrosion, in the cell, this happens as a result of failed biochemical reactions, genetic mutations, and transcription errors.
At first, these errors are benign, but as they mount up, the cell becomes less effective at carrying out its many functions. Ultimately, the cell reaches a point where it can no longer perform its duties effectively; when this happens, it will self-destruct in a process known as apoptosis.
Our cells are constantly doing this every day. Anytime we shed a skin cell after a sunburn or when our immune system kicks in—this process occurs. In fact, most of the cells that make up who you are today are not the same cells that were around when you were younger.
To compensate for the loss, nearby cells will divide and create two daughter cells—from muscle regeneration to bone remodeling—this is how our body heals.
The problem—as aging researchers have learned—is that our cells can only divide a set amount of times. It is this cellular upper limit that gives us what we call our biological clock. The dreaded countdown to our inevitable demise.
There are several reasons why our cells can only divide so many times. One notable cause is that our cells have something called telomeres that are responsible for preventing genetic errors. They are like buffers at the end of our DNA that prevent crucial nucleotides from breaking away and degrading our genetic code.
Each time a cell divides, these telomeres degrade away instead of our genetic code. But the problem is that the telomeres get shorter and shorter until at last they run out and stop doing their job. Once our genes begin to degrade, the cell cannot continue to divide. Which means they must die off.
What’s worse is that the daughter cells inherit this shorter telomere as well. And on it goes, with each cell generation moving closer and closer to the end of its life.
So what does this have to do with fasting? It comes back to that cellular “wear and tear.” Because the greater the metabolic load we place on our cells, the sooner they will undergo multiple errors. The sooner they will need to die off, and the more often that other, healthier cell will have to divide. And because telomeres don’t last forever. More cell divisions mean a shorter life span—like driving a car an hour to work each day, which puts more miles on it and forces it to reach the end of its life much sooner.
Therefore, one way to look at fasting is by recognizing that our cells have limits, and giving them a lighter metabolic load will lead to longer-lasting cells. Longer-lasting cells mean fewer cell divisions. And fewer cell divisions mean longer life.
Not just fasting
You don’t have to fast to get this benefit. It can be done through calorie restriction too. This involves eating regularly throughout the day but taking care not to eat too much. It is here that we have some of the strongest evidence for the connection between lifespan and caloric intake.
The problem is that many of us find it strikingly difficult to do.
This is because eating a lot of calories appears to be hardwired into our brains by the forces of evolution. Eating as many calories as could be found was a biological priority for much of human history, since food had to be painstakingly sought out and was not always consistently around.
So when a hunter-gatherer foraging in the forest stumbles on some berries that may be dead or rotten in a couple of days, they will do what they must do to get all those calories into their bodies and not waste food. Such are the behaviors we have inherited from our ancestors over the millennia, and such is the reason why they are so hard to resist. They have been long laid by generation after generation of survival of the fittest.
The problem is that this need no longer applies in most corners of the world. Food is everywhere now, courtesy of the Industrial Revolution.
Intermittent fasting: the glutton’s solution
For those of us who don’t do well trying to keep our portion sizes small, intermittent fasting is a great option. It utilizes the same science as calorie restriction, but it does so in a different way. By narrowing your eating window, you can minimize the number of calories you take in each day, and this can be a great tool for weight loss.
The cells still get a break from the metabolic load, and the long period of non-eating closely aligns with our evolutionary past of not knowing where our next meal will come from. For this, our bodies are calibrated and aligned.
Conclusion
Intermittent fasting (IF) has evolved from early 20th-century scientific curiosity to a widely embraced practice backed by decades of research and modern accessibility. IF offers a practical approach to health that aligns with our evolutionary biology. By reducing the metabolic load on our cells, fasting not only supports weight loss and metabolic health but also holds the potential to extend lifespan by slowing cellular aging. IF provides a sustainable alternative to traditional calorie restriction, empowering individuals to harness the science of fasting for a healthier, longer life.
Have you ever tried intermittent fasting? Leave your thoughts in the comments below.
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