Hour by Hour Benefits of Intermittent Fasting

When it comes to intermittent fasting, every second counts. Your 12th hour is not equal to your 17th hour, for example, so it is important to truly understand the EXACT hour by hour benefits of intermittent fasting so that you can maximize your time spent fasting while reaping the most weight loss and health benefits possible.

90 minutes into fast

Your last meal was consumed an hour and a half ago and your blood glucose levels are at their peak. How high your blood glucose spikes depends entirely on what you last ate, so choose your final meal carefully. 

As you will soon find out, this last meal you ate is going to dictate how these new few hours of your fast go. 

💡 TIP: Turbo boost your body’s fat-burning power by consuming a lower carbohydrate meal as the last meal before your fast. By limiting carbohydrates, you will be entering your fast with a lower glucose supply, in turn speeding up the rate at which your body makes the critical transition from using food as energy 🠚 burning fat for fuel. 

Not only with you maximize your fast by spending more hours in the critical “fat-burning zone,” but this practice will also facilitate your body’s ability to rid itself of damaged cells and protein waste. This process is called autophagy, which you will see again around the 24-hour mark.

4 hours into fast:

By the four hour mark, all food has left the stomach. Your last meal is now making its way to the small intestine.

Your body is done producing insulin and your blood sugar levels drop.

A majority of fasters begin their fast after their evening meal, putting them right at bedtime around the four-hour mark. 

10-12 hours into fast:

Again, for many fasters, this 12-hour point tends to fall around the time they wake up. Assuming you finished eating at 7pm and wake up at 7am the next day, you will already be 12 hours into your fast and just gearing up for some serious benefits.

By now, your digestive system has gone to sleep. With all food consumed already digested and burned through (or stored away as energy), your body is finally ready to shift focus onto other necessary functions.

This is where things get interesting, and where the hour by hour benefits of intermittent fasting really start to pick up.

14-16 hours into fast:

Human Growth Hormone begins to increase.

Glucose levels are now depleted and your fat stores “unlock.” Your body is now burning fat for energy.


Going back to our example, let’s assume you finished eating your last meal at 7pm. It is now about noon the next day – meaning many of the more casual intermittent fasters are already preparing for their next meal. 

For those following a 16:8 fast, for example, the buck stops here.

Unfortunately, many intermittent fasters “break fast” right at this critical moment where health benefits and fat loss begin to skyrocket.

18 hours into fast: 

Ketone levels spike.

To give you an idea of just how dramatic this increase is, the non-fasting concentration of ketones in your plasma is somewhere between 0.05-0.1mM. This number skyrockets up to 5 – 7mM while in a fasted state – signifying a dramatic switch as your body begins using your existing fat stores for energy. Those following a lower carbohydrate diet can also see a similar increase due to the limited availability of glucose energy circulating in the bloodstream.

You are now a fat-burning machine.

24 hours into fast:

Autophagy begins. Within 24 hours, your body is in full-on healing mode. Damaged cells and protein waste are being broken down, and what can’t be recycled is burned for energy. 

Most individuals following a typical 12:12 eating plan –  meaning fasting from dinner to breakfast the following morning – never give their cells a chance to initiate autophagy. By not making room for this important cell-turnover process, the body can become rampant with diseased cells – in turn wreaking havoc on the entire system.

Intermittent Fasting Diet Plans and Schedules:

As you can see, some of the more impressive health benefits of fasting don’t start appearing until well into a fast. While it can take some time to build up to a 24+ hour fast, those looking to reap the benefits of autophagy may be interested in trying the 5:2 method, for example, as it allows for two longer fasting periods a week and five days of feasting freedom.

Of course, it is much easier to start slow and work your way up as you give your body a chance to adapt to this new way of life. There are many great benefits of shorter fasts too, so don’t let this timeline discourage you. Many people have seen incredible health and weight loss results from intermittent fasting without ever fasting longer than 18 hours!

Find out which of the 7 Most Popular Intermittent Fasting Schedules for Weight Loss is right for you.

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