How Intermittent Fasting Works for Fat Loss

How Intermittent Fasting Works for Fat Loss

Video | Definition | Weight Loss Models | How Fasting Works 

If you’re looking for a tool to speed up fat loss, intermittent fasting is worth a look. In this blog post, I explain how intermittent fasting causes your body to burn fat. 

Intermittent Fasting Basics


  • Fasting involves splitting your day between periods of eating and not eating (fasting)
  • The most popular version is 16:8 fasting, which is a 16-hour fast in a 24-hour period
  • Weight loss and gain is controlled by hormones, especially insulin.
  • To burn body fat, your body must be low in stored glucose (glycogen) and insulin
  • When you fast, your body burns through some of the stored glycogen and insulin levels drop making fat burning possible

How Intermittent Fasting Works for Fat Loss [Video]

In this video, you’ll learn…

  • The old way of thinking about weight loss.
  • A new approach to weight loss.
  • How intermittent fasting can help you achieve your goals.

What Is Fasting?

Intermittent fasting is a simple concept that is practically defined by its name. It involves incorporating periods of fasting into your diet. 

The length of time for intermittent fasting varies, but a popular time frame is 16:8 meaning that you fast for 16 hours and consume all of your calories within an eight-hour eating window. 

This method of timing your eating has proven to be very effective for even stubborn metabolisms, but to really appreciate why it works, we need to take a fresh look at how weight loss happens.

intermittent fasting

The Old Model of Weight Loss – Calories In/Calories Out

We used to think that the Calories In/Calories Out model was how we lost weight. Which basically meant that all calories were equal, so 100 calories of meat equaled 100 calories of cake, which equaled 100 calories of salad.

When you consumed those calories, we assumed that they went into a collective bucket in your body and sat there until you needed some energy at which time the calories in the bucket were released and burned. The logic was that if you burned more calories than you consumed, weight loss happened. 

That model of how the body burned fat seemed logical, but it didn’t seem to work. In fact, the calories in/calories out model has been the predominant way of thinking for the past 60 years, which was a period that was marked by skyrocketing obesity rates.     

The New Model of Weight Loss – Hormonal Control

The reason that the Calories In/Calories Out model does not work is because calories are not simply dumped into a collective bucket in our bodies.

Instead, the calories that are not used immediately are directed into two separate storage containers and stored as either glycogen or fat. The movement into those storage containers is controlled by the hormone called insulin. 

where calories are stored

Insulin shows up in the blood when food or caloric drinks are consumed. When the level of insulin is high, food energy is being stored, and cannot be released. In other words, food energy moves in one direction at a time. It is either being stored or being released and it all depends on how much insulin is present.  

How Calories are Stored

As I mentioned earlier, calories that are not used immediately are stored as either glycogen or fat. 

Glycogen is an easily accessed storage container because it is essentially stored glucose, which is easy to burn. But the glycogen container is small. You only have about 2,000 calories of available energy stored as glycogen. 

Fat, on the other hand, has a lot of energy. Just one pound of fat has about 3,500 calories worth of energy, but fat is hard to access. 

How Intermittent Fasting Works

For your body to go to the trouble of burning body fat for energy, two things must happen. 

  • You must be running low on glycogen. 
  • You must have a low level of insulin in your blood.

How do you get into these states? You stretch out the time between meals. In other words, you follow an intermittent fasting strategy

how to burn fat

If you are eating frequently throughout the day, you are constantly refilling glycogen stores and bumping up insulin.

Because there is a constant supply of glycogen, there is no need for your body to go to the trouble of converting fat into energy. Even if your body wanted to burn fat, it could not access it because the insulin levels never drop to a point where fat can be released.  

When you stretch out the time between meals by practicing intermittent fasting, your body burns through some of the stored glycogen and insulin levels drop making fat a logical choice for your body to run on. 

About the Author:

Dr. Becky Gillaspy, DC graduated Summa Cum Laude with research honors from Palmer College of Chiropractic in 1991.

Get Our FREE Guide to Fasting!

Finding the right fasting routine for your body and lifestyle takes time. If you’d like to avoid common fasting mistakes and find ways to make fasting easier, I encourage you to download this FREE guide!

Get your FREE “How-To” guide to fasting here!

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