What is Fasting?
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Fasting has been around for thousands of years. Many religions, ancient and modern, have used fasting as a means of purification, penance, or spiritual enlightenment. The ancient Greeks believed it offered physical cleansing and renewal, while some primitive cultures swore by pre-war fasts to strengthen the body and the mind.
Fasting is often confused with starvation, but there’s a big difference. Starvation is the complete, extended absence of energy intake and nutrition, and has serious health consequences. Fasting, on the other hand, involves redistributing energy intake for longer periods of ‘rest’ from eating than normal.
Intermittent fasting encourages the body to effortlessly use fat for fuel, rater than constantly storing excess food as fat without ever using it, which is quite common in today’s patterns of constant eating!
While skipping just the occasional meal can be beneficial, cycling periods of fasting (usually in the morning) and eating (usually at night) can aid detoxification, encourage fat burning, and improve immune function.
To understand the power of fasting, let’s first take a look at how it works...
HOW FASTING WORKS
Many people find the idea of fasting intimidating, but what they don’t realize is that we actually fast every single day to some degree. When you’re asleep, you’re fasting, hence the name ‘breakfast’, or ‘break fast’. In between meals, you’re fasting. In fact, whenever you’re not eating, you’re fasting. Here’s how it works...
At any given time, the body exists in one of two natural states — fed or fasting. The purpose of the fed state is to store energy, while the purpose of the fasting 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 elevated levels of glucose in the blood, it releases insulin.
Insulin helps your body’s cells take in and use glucose for energy. Most of us typically take in more energy than needed, so when the cells have enough, insulin signals to the liver to store the 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 FASTING STATE
When not eating, that process is reversed. As blood glucose levels fall, the pancreas stops receiving the signal to produce insulin.
To power the body, it looking for energy stores. The easiest to access is glycogen, which is released by the liver and broken down into glucose.
There is usually enough glycogen to last 24-36 hours. When this runs out, the body turns to its fat stores. Here is weight loss happens; the body literally burns away the fat.
We are biologically designed to achieve balance between these two states. If constantly in a fed state, then there will always be an excess of blood glucose and full glycogen stores, leading to increased fat storage. If always in a fasting state, then both fat and glycogen stores get depleted.
That’s where the confusion between fasting and starvation comes from. Starvation is what happens when food intake is restricted for such an extended period that all energy stores are depleted and the body starts breaking down tissue like muscle to survive.
Fasting, on the other hand, is a temporary state that allows the body to burn through those energy stores, leaving room for more when returning to the fed state. It’s a perfectly natural and healthy cycle of energy intake, usage, and replenishment, as opposed to the dangerous one-way process of starvation.
Metabolic Flexibility is the ultimate goal of any fasting lifestyle. When the body is metabolically flexible it means it can shift from burning carbs (or glucose) or fat for fuel without changes in energy, mood, sleep or weight.