Intermittent fasting (IF) has emerged as a popular trend in recent years among self-improvement enthusiasts. I dabbled in it two years ago, but last month marked my first real attempt (inspired by the YouTube channel What I’ve Learned), and I absolutely love it. This article will explain the science behind why it works and how to do it properly; the many benefits of IF are covered in my blog “Intermittent Fasting: The Payout.”

 

What is Intermittent Fasting?

 

Fasting is simply the act of not eating. While fasting traditionally stretches for days or weeks at a time, you can practice intermittent fasting without skipping a single day.

 

Many people who practice IF follow a 16:8 rule; 16 hours of fasting with an 8 hour eating window each day, though many have a longer fasting window than that. The longer the fasting window, the better the results. I began with a 16 hour fasting window myself, and have since moved into the 18-20 range, with a noticeable difference.

 

How does fasting work?

 

Many people believe that weight gain = calories in – calories out. This appears to be simple physics, and yet it is completely wrong. To understand how energy consumption really works, we must turn to glycogenolysis, gluconeogenesis, and other terms that I vaguely recall from high school biochemistry.

 

Hormones play a vital role in energy conversion and storage. Insulin builds glycogen (a short term fat storage) from glucose (the sugar in your bloodstream). Insulin also blocks leptin, the hormone that tells your brain when you are full. Insulin helps your body absorb glucose, but it also converts the excess into fat, and then leaves you feeling hungry.

 

Glucagon is responsible for glycogenolysis, the process of breaking glycogen back down into glucose to provide the body with energy. Your liver cannot begin to produce glucagon until your blood sugar has dropped, which takes roughly 6 hours from the time you last ate.

 

Insulin counteracts the effect of glucagon, which means it prevents you from burning glycogen for fuel until you have gone several hours without eating. Insulin also interferes with the action of hormone-sensitive lipase, which breaks down fat for energy.

 

In order for your insulin levels to drop, glucagon to be released, and hormone-sensitive lipase to tap into your fat stores for energy, you need to go at least 6-8 hours without consuming carbohydrates (especially sugar). At this point, your body enters a state called ketosis, in which your body uses fat for energy, rather than carbs. Fasting keeps you in this state, allowing you to burn your fat stores.

 

Won’t Fasting Make Me Hungry?

 

Hunger relates differently to intermittent fasting, traditional fasting, and caloric restriction; I will focus only on IF for this question.

 

Firstly, IF allows your body to access the energy stored in fat―caloric restriction does not. Once your body enters ketosis, you can burn your fat stores for energy, so you don’t have to keep eating more carbs (i.e., no hunger).

 

There is another reason why appetite subsides when fasting―ghrelin. This hormone tells the brain when it is time to eat. Have you ever felt content until you took one bite of food, only to suddenly become ravenous? That was ghrelin at work.

 

Ghrelin is released in anticipation of food; this cue can even come from your body’s natural rhythms. That is why you can work through lunchtime, feeling hungry, and then discover that you’ve lost your appetite. Your body releases ghrelin around the times you generally eat, and this spike drops off within an hour or two―even if you ate nothing.

 

This is the real reason why adjusting to intermittent fasting starts off challenging, and then becomes effortless. As your body adapts to a new eating schedule, your ghrelin cycles adjust, and you simply don’t feel the need to eat outside of that window.

 

For myself switching to a 1-2 p.m. breakfast, the first three days were fairly difficult. At the end of my first week, it barely required willpower. By the end of my second week, IF had started to become fully automatic and natural.

 

When I ate breakfast at 10 a.m. with a visiting friend, I simply chose to eat―it fascinated me that I essentially had no craving for food at that time, but I was still comfortable eating. I felt like I had literally transcended beyond primal urges. Better yet, breaking my fast early one day did not ruin me for the next―this habit takes time to build, but it does not fall apart easily, either.

 

Conclusion

 

In summary, intermittent fasting is completely different from caloric reduction, because it relies on the sound science of hormones to make your body work for you. For someone like myself who burns many calories and possesses little fat, IF makes much more sense for my lifestyle than traditional fasting (as excellent as that is), and it is much easier to do.

 

Go forth and conquer!

 

 

 

The sequel to this blog, “Intermittent Fasting: The Payout,” describes the actual health benefits in more detail, and closely compares IF with traditional caloric restriction.