What is intermittent fasting?

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Intermittent fasting has recently become a popular method to lose weight and improve health. If you’re considering trying intermittent fasting, make sure to discuss it with your physician first, just like any diet plan, activity or change in your health regimen.

But what exactly are the health benefits, and what’s the science behind this new trend? 

Intermittent fasting is really nothing more than compressing your “feeding window,” which is the window of time that you eat each day. 

How our eating habits have changed

Things have changed quite a bit over human history. In the beginning, we didn’t eat and snack all day long. When food was there, we feasted. When food wasn’t there, we couldn’t eat. Therefore, our bodies have been designed to go through these cycles of eating more or less at certain times. 

As a result of the Industrial Revolution, changes in our nation’s food supply and our ideology regarding food and nutrition, we’ve been told we should eat more often, like eating small meals throughout the day to keep our blood sugar from dropping. 

However, the data and the science are now pushing back on this idea. People are starting to question why we as a society have adopted the idea of eating all the time. 

The science behind intermittent fasting

Some experts have pointed out that many Americans are eating during 75% of their waking hours. This lifestyle of continuous eating may have serious repercussions on our bodies and our health. The overall body of knowledge in this area continues to increase. 

That’s why there’s been a current resurgence of the ancient idea of fasting. If you think back to our ancestors, they weren’t staying up until 11 p.m. every night eating chips and dip. They went to bed when it got dark and ate again when the sun rose. They were naturally fasting every day using their circadian rhythm

Your body goes into a natural fasting period whenever you stop eating at night to the next time you eat the following day. The remaining hours in your day are considered your feeding window. 

How intermittent fasting works

Intermittent fasting focuses on compressing feeding windows on a regular basis. For example, many people who practice intermittent fasting aim to stop eating every night by 8 p.m. and do not eat the next day until around noon. This creates a 16-hour cycle of fasting and an eight-hour eating window. 

I began doing my own research on intermittent fasting after a minor health scare, and soon became compelled to try it based on the evidence. I knew after having recent lab tests done that my insulin levels were too high, my blood glucose levels were too high and several other test results were off. Through my research, I learned that one of the quickest ways to improve my health status was through fasting.  

Science and technology have allowed us to understand what happens to our bodies when we fast. After you eat, your body takes the food you eat and turns it into glucose. This glucose goes into your blood stream to be used as energy. 

About 12 hours into fasting, your body is running off the glucose stored in your blood. After all of that glucose is consumed and utilized, your body has to find another source of energy. This is when you may begin to feel sluggish or lethargic. 

If you continue to fast, your body then turns to your liver for energy. Your liver stores glycogen that can be easily turned to glucose. 

After 14-18 hours into fasting, your body has emptied all the sugar out of the blood and liver, so it starts to break down protein into sugar. This process is called gluconeogenesis. 

Myths surrounding intermittent fasting

This stage in the process has been a source for many myths surrounding intermittent fasting. Many people think that fasting is bad for you because it breaks down muscle, but the body is smarter than that. The body targets damaged proteins in muscles rather than healthy proteins. 

After approximately 16-24 hours of fasting, your body starts to tap into fat cells and transitions them into chemicals called ketones. Ketones are fuel we can use and are especially beneficial for our brain. Many people claim to have extreme brain clarity at this stage of fasting, similar to what many people call a “runner’s high.”

What are the health benefits?

Besides losing body fat, there are many health benefits to intermittent fasting. Studies show that intermittent fasting helps lower hemoglobin A1C in those with diabetes and in some cases, reverses Type 2 diabetes.

Cancer researchers are also looking at fasting to lower blood glucose in the body, which is the only fuel that cancer cells can use for energy, to see if it can slow cancer cell metastasis. Intermittent fasting is an ancient practice but a young science, so there are still a lot of benefits to discover.

Reminder to talk to your physician first before starting a new health regimen like intermittent fasting. I would also encourage you to do your own research to decide if intermittent fasting is right for you. 


Mr. Langham has been with the company since October 2008 and currently serves as Executive Vice President of Clinical Excellence and Strategy. Prior roles at Enhabit include Chief Strategy and Innovation Officer and Chief Clinical Officer. He is a physical therapist by training and has direct patient care and leadership experience in a variety of acute and post-acute settings. Mr. Langham received his degree in physical therapy from the University of Oklahoma Health Sciences Center in 1999 and a Master’s Degree in Business Administration from the University of Oklahoma in 2005. He is an active member of the American Physical Therapy Association and has served on multiple technical expert panels (TEPs) for the Centers for Medicare and Medicaid Services (CMS).

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