Intermittent Fasting

Introduction to Intermittent Fasting

November 2, 2022

Intermittent fasting is everywhere these days, but exactly what is it?

A Little More Wait Equals A Lot Less Weight

That pretty much sums it up. Intermittent fasting is just waiting to eat. Wait until the time you choose to start eating. Eat. Stop at the time you choose to stop. That’s it. Then do it again the next day.

Some terminology:

The eating time is called a “window”-it’s called a window because you can open and close it. You pick whatever times you want to open and close it. You have one eating window per day. Whatever window works best for you is the one to choose. Although most people call this intermittent fasting, fasting is a little harsh of a word for what’s actually going on. Fasting- as we usually use the word- implies going for long periods of time without food and feeling hungry and sort of suffering, but intermittent fasting isn't like that at all. It’s less “fasting” and more just waiting to eat each day so that all your calories are compressed into a shorter period of time than usual for you.

In the first few weeks, you may feel hungry as the opening time for your window approaches. That is because our bodies are used to our eating patterns and give us cues-hunger-as we near our meal time. As you get used to your new, shorter eating window, all the internal machinery that gets your hunger going slowly begins to change- it adapts to your new eating pattern so you feel less and less hungry. That’s where the magic happens. As you get further away from your last meal, your body burns more and more of your own fat for fuel. There are many, many benefits to burning your own fat for fuel-way too many to list here in a blog post- so I’ll just give you a few:

  • Decrease in insulin resistance and prediabetes
  • Decrease in inflammation
  • Decrease in weight
  • Decrease in cravings
  • Increase in energy
  • Increase in metabolism

And one last amazing bonus is you learn the difference between feeling hungry and wanting to eat. Yes, they’re different. How freeing would that feel? To not feel like you “need” to eat. To go through your day not even thinking about food. It’s hard to believe it could even be true. Let me tell you, as a chronic dieter who was always hungry, intermittent fasting frees you from food jail. It’s bliss.

Windows of Intermittent Fasting

There are different ways to create your window schedule-the amount of time you eat (open window) and the amount of time you don’t (closed window). All are effective for dropping fat and improving blood sugar. Ultimately, it comes down to what works best for you in your life. THIS IS A KEY DIFFERENCE between dieting and IF. Dieting imposes the structure on you-all the way down to what you can and cannot eat. That’s not Intermittent Fasting. You eat what you want when you want. You choose. As long as you are compressing all your calories into the time frame you choose, that’s it. You’re doing it.

The most popular eating window is an 8-hour eating window. You eat all your calories in an 8 hour time frame every day. One way to do this is don’t eat after dinner and then skip breakfast. This approach works well for many people. It’s pretty easy to do, very easy once you get used to it, and fits well into most people’s schedules. If it works with your daily life, try it. If it feels good, keep going. Many people find that using a smaller eating window-4 hours for example-works better for them. They lose weight more quickly and have better improvements in blood sugar. This would be a 20:4 schedule.

There are fasting options that do not include eating everyday, called alternate day fasting. Some people LOVE this approach. It lets them go completely without thinking about food for a day; there’s no shopping, cooking, cleaning up, worrying about calories, stressing about overeating, just a day of rest. Food rest. Gut rest. Once you become a more experienced faster and can go longer without eating because you are burning your own fat for fuel, try this approach. It may be the one for you.

Let’s talk about hunger

“I can’t fast because I’m going to be soooo hungry.“
“I can’t fast because my blood sugar will drop.”
“I can’t fast because …….”

That fear is real and comes from your experience of trying to lose weight in the past. It’s based on how you feel after not eating if you haven’t built your body’s machinery to use your own fat for fuel.

If you are a “sugar burner”, in other words if you eat frequently, you are constantly fueling yourself from the carbohydrate you last ate so you do get hungry when you’ve burned through that food. Then you feel you need to eat again to get more fuel. What you want is to dip into your reserves-your fat-but you can’t because your fat burning machinery is not trained to step in and provide you with fuel. Use intermittent fasting to get this machinery up and running so you can burn your fat for fuel. When you do this, you actually don’t feel hungry. Because you already have all the fuel you need. You are carrying it around with you every day. When you switch your body over from looking for the next meal for fuel to using what you’ve got on you, you don’t get hungry. Your body just keeps going back for more and you run the way you were meant to run.

Which intermittent fasting plan you choose depends on your goals. If you want to eat every single day - if that is important to you - choose a daily window like 8 hours eating, 16 hours fasting. If you are in more of a hurry to burn fat, or just have more fat available for fuel, use a narrower window, like 4 hours eating and 20 hours fasting. The longer you fast, the more time you spend burning your fat. The more fat you burn, the healthier you get and healthier equals happier.

Editor’s Note: This is the first article of a three-part series. Be sure not to miss Dr. FitzGerald’s articles to follow:
Intermittent Fasting, Can It Be Harmful If I Am Diabetic?
How Can Intermittent Fasting Affect Your Metabolism for Weight Loss?

Cecily FitzGerald, MD, offers online health coaching and weight loss programs: science based, science backed.

Intermittent Fasting
Cecily Fitzgerald


Cecily FitzGerald, MD, is a board-certified physician in practice for over 30 years. She is a graduate of Cornell University and Eastern Virginia Medical School. Residency trained in Emergency Medicine, she also has fellowship training in Genetics and Clinical Research. She now offers online health coaching and weight loss programs: science based, science backed.