What is fasting and should you do it?
Fasting is the practice of restricting your food intake for set periods of time. We’ve known about its incredible health benefits for thousands of years, with almost every ancient culture practicing fasting for a variety of reasons.
For example, the ancient Greeks used fasting for cleansing and renewal, while some cultures fasted to strengthen the body and mind before a conflict. Fasting was a popular religious practice too, used to achieve purity, enlightenment or penance.
Most religions continue the practice today, with ritual fasting on holidays like Ramadan and Yom Kippur. However, fasting without a religious or cultural association is often considered unhealthy, dangerous, and even a sign of mental illness.
In this article, we’ll dive into the science of fasting and its many benefits, but first let’s break down the biggest misconception about fasting…
Isn’t fasting a form of starvation?!
No! People often assume that fasting and starvation are the same thing, which is why you’ll often get raised eyebrows and concerned looks when you tell your friends you’re on a fast. Here’s the difference.
Fasting, or being in a fasted state, happens when you temporarily restrict your food intake. At this point, your body is using stored glucose and fat to make energy.
Starvation is the state that results from the absence of food and nutrients for an extended period of time, to the point where the body has used all of its stored energy and is forced to break down its own muscle and other tissue for survival.
So when we talk about fasting, we’re NOT talking about starving yourself! Your energy stores are never depleted to the point of starvation, not even close, and you’re maintaining proper nutrition during your eating periods. You’re simply taking a longer “rest” from eating, and here’s why that’s actually a biological necessity.
The science behind fasting
Did you know that you already fast every single day to some degree? You’re fasting when you’re asleep, hence the name ‘breakfast’, or ‘break fast’. You’re fasting in between meals. In fact, whenever you’re not eating, you’re technically fasting.
At any given time, your body is in one of two natural states — fed or fasted. The purpose of the fed state is to store energy, while the purpose of the fasted state is to burn energy.
The fed state
When you eat, the energy from your food is broken down into glucose. When your pancreas detects this glucose in the blood, it releases insulin, which helps your cells to take in the glucose for energy.
There’s usually more energy in your food than your cells need, so insulin tells your liver to store any excess glucose as glycogen for future use. There’s only so much space in the liver, so any further excess glucose is turned to fat and deposited around the body.
The fasted state
When you’re not eating, the process is reversed. As your blood glucose levels drop, your pancreas stops producing insulin. You now need to start burning your energy stores.
The easiest form of stored energy to use is glycogen, which is released by your liver and broken down into glucose. You have enough glycogen to power you for around 24 hours, after which point your body will turn to its fat stores.
The right balance
In prehistoric times when food was very scarce, we had to be able to survive for days at a time without eating. We evolved to store excess energy when we could eat (the fed state), and use that stored energy when we couldn’t (the fasted state).
We’re biologically designed to alternate between those two states. If we’re always in a fasted state, we’ll eventually run out of stored energy and starve. But if we’re always in a fed state, we’ll always have too much glucose, full glycogen stores, and excess body fat.
The consequences of never being hungry
Unfortunately, modern Western life has completely disrupted the natural balance between our fed and fasted states. We have constant access to food and we cannot tolerate hunger, nor are we encouraged to. Being hungry is considered unacceptable, and we’re told to bridge the gap between meals with snacks or “mini meals”.
This means we hardly ever experience the natural fasted state we need for optimal health. We exist almost permanently in the fed state, and the food we eat is often packed with energy but devoid of nutrients.
The potential consequences of living entirely in the fed state are severe — heart disease, stroke, diabetes, and premature death, to name just a few — but restoring the balance with regular fasting can go a long way towards protecting your health.
The benefits of fasting
There are so many health benefits to be gained from fasting that the topic merits its own article (coming soon!). Here are just a few of them:
I fast regularly and I recommend the practice to many of my patients. In our combined experience, fasting has led to significant improvements in everything from energy levels and mood to weight and chronic pain.