How Intermittent Fasting Works

Tom Corley boats - crop

Have you ever heard of Intermittent Fasting?

I’ve been studying Intermittent Fasting since 2007. That’s when I discovered that 30% of the self-made millionaires in my study used it to stay lean (thin).

What is Intermittent Fasting?

Intermittent Fasting is the reduction in the number of meals you eat during a 24 hour period from three meals to two meals or even to one meal. Viewed another way, Intermittent Fasting requires that you avoid eating any food for long periods during the day.

Why Engage in Intermittent Fasting?

Intermittent Fasting burns body fat and provides the cells in your body with 20% more energy.

How Does Intermittent Fasting Work?

Every cell in the human body requires either Glucose or Ketones in order to survive. Each cell in the body has thousands of mitochondria residing inside their individual cells. These mitochondria are the power plants of every cell. The mitochondria within each cell absorbs either glucose or ketones and then converts glucose or ketones into ATP. The mitocondria then use ATP as fuel to power their cell and keep it alive.

We get glucose from most of the food we eat. Carbohydrates, for example, are packed with glucose.

We get ketones from body fat. Ketones are stored in fat cells throughout the body. An interesting thing about ketones is that, when converted to ATP by mitochondria, they produce 20% more ATP than glucose. So, ketones provide cells with 20% more energy.

When your body begins to run out of glucose, the vagus nerve sends a signal to the brain, informing it that the body needs more glucose. The brain then sends a signal to the stomach, through the vagus nerve, to start eating. Your stomach then begins contracting. We call those contractions, hunger pains.

If you ignore those hunger pains and forgo eating, the body will run out of glucose. Once the body runs out of glucose (typically four hours after a meal during the wake state), it has no choice but to begin burning fat cells in order to release the ketones stored inside those fat cells. This then shrinks the size of your fat cells. The longer you go without eating, the longer you stay in this Ketonic State and the smaller your fat cells get.

The second you eat food, you revert back to the Gluconic State and your body stops burning fat cells.


Let’s say you go to bed at 10pm. At some point during the night, typically about six hours during the sleep state, your body will run out of glucose. When there is no more glucose, the body will enter the Ketonic State and start burning fat cells.

If you sleep seven hours a night, you will wake up around 5am. When you wake up you will have been in a Ketonic State for one hour. If you forgo eating breakfast, your body will remain in a Ketonic State until you eat lunch. If you eat lunch at 12pm, you will be in a Ketonic State for another eight hours. That means your body will have burned fat cells for nine straight hours.

The minute you put any food in your mouth at lunchtime, you immediately exit the Ketonic State and revert back to the Gluconic State.

Now, let’s say at lunchtime you eat less than 400 calories. Well, those 400 calories will only provide your body with about two to three hours of glucose. So, sometime around 3pm you will begin to get hunger pains, informing you it’s time to consume more glucose. If you ignore those hunger pains, you once again enter the Ketogenic State.

If you typically eat dinner at 6pm, this means you will have been in the Ketonic State, burning fat cells, for another three hours.

When you do the math, this means you will have been in a Ketonic State, burning fat cells, for twelve hours in one twenty-four hour day. For twelve hours your body was burning fat cells in order to release the ketones it needed to fuel your body.

Here’s another interesting thing that happens when you engage in Intermittent Fasting –  your stomach begins to shrink.

When your stomach shrinks, it takes less food to fill it up. When your stomach senses that it is getting full, it sends a signal to the brain, through the vagus nerve, to stop eating. This means you consume fewer calories as you don’t have to eat as much food in order to feel full.

Remember, every time you enter the Ketogenic State, you force your body to burn fat cells. Every time your body burns fat cells, your fat cells shrink. The key to losing body fat, therefore, is to remain in the Ketogenic State for as many hours as possible. You do this by reducing how many meals you eat every day. Some people who engage in Intermittent Fasting can get by with one meal a day, others require two meals.

Be Sociable, Share!
Thomas C. Corley About Thomas C. Corley

Tom Corley is a bestselling author, speaker, and media contributor for Business Insider, CNBC and a few other national media outlets.

His Rich Habits research has been read, viewed or heard by over 50 million people in 25 countries around the world.

Besides being an author, Tom is also a CPA, CFP, holds a master’s degree in taxation and is President of Cerefice and Company, a CPA firm in New Jersey.
Phone Number: 732-382-3800 Ext. 103.
Email Tom
| Download Media Kit


  1. In my experience, the results of fasting can really be astounding. Since IF isn’t a diet, rather a pattern of eating or a way to schedule your meals so that your body gets the maximum benefit out of each one, it’s easier for people to follow. And if you think about quality of food you consume and incorporate physical fitness it can be a healthy lifestyle. Also when followed properly, intermittent fasting along with portion control (I wrote about it here: can be a great weight loss strategy for almost anyone.

Speak Your Mind