Intermittent Fasting – Facts, Fad or Foolish?
While I was scrolling through social media the other day, I came across a “Diets through the Decades” image that I couldn’t help but chuckle at. Anyone remember The Sleeping Beauty diet that swept through the 70s? Or what about The Baby Food diet from the early 2000s? Sometimes it feels like every time we jump online there is some new trick to help us lose weight fast that inevitably causes more issues to our bodies. One of the new ways of eating that has gained a ton of interest is Intermittent Fasting. Intermittent fasting has been a hot topic in the fitness and longevity literature for the past several years. Intermittent Fasting (IF) is the dietary method of avoiding food for extended periods of time. Before you freak out, I’m not asking you to starve yourself! Let me explain how it works in the literature and how I use it in my own daily life.
Peter Attia MD, one of the foremost researchers and speakers on health, explained that “fasting is the most potent tool in your toolbox of nutrition”. Our bodies desperately need a break occasionally from all the junk that we consume. With IF, we are seeing that our bodies are getting a chance to heal from the inside out. If you read my last blog post, I mentioned that 70% of our immune system is in our gut. IF, although not directly, is a way for us to support our immune systems and let our bodies detox for a portion of each day. Not so scary, right? Okay, let’s talk about how it works. Fasting is a mixture of three elements:
The amount of calories you restrict (100% full calorie restriction): Many people use their time sleeping to jump start their IF and continue until 10am before consuming any calories. For those of you groaning about not getting your morning coffee, remember black coffee is calorie free so you are still okay!
Duration of the fast: Each person is different on how much time their body can tolerate going without calories. I will discuss common IF patterns below.
Frequency that the fast is repeated: IF is not something you have to do every day. Even just 3-4 days a week is better than not at all!
So, what is the science and why should I do this?
Fasting suppresses something called mTor (large topic not discussed here, but basically mTor plays a key role in development and aging). mTor suppression, in turn, leads to autophagy. Autophagy is the process by which the body rids itself of dysfunctional cells (aka detoxing!). Autophagy helps get rid of the cells that could cause disease, inflammation and cancer. Fasting improves insulin sensitivity and blood glucose control leading to prevention of diabetes. Fasting can also reduce obesity and assist in weight loss due to calorie restriction. It also has the potential for improving brain health and lowering risk of dementia. Finally, fasting may lead to longer lifespan and greater healthspan.
Okay, we got through the science of IF but how does it actually work?
Like I said before, each person is going to be a little different in how long they fast and when they choose to fast. Here are some of the different types of fasting methods:
Restrictive Time Eating - most common method where one eats during a set time window and fasts for the remaining hours. A traditional fasting window is 7 pm to 11 am and then you are free to eat what you like from 11 am to 7 pm. This is what we call the 16 / 8 method because you are fasting for 16 hours and then eating all your daily calories within an 8 hour time period. Restrictive Time Eating can be adjusted to fit your schedule and, while the eating window can be shortened, it should not be longer than 8 hours to see the benefits of fasting. My wife prefers a 20 / 4 method where she fasts from 8 pm to 4 pm and consumes all of her calories from 4 pm to 8 pm.
Another type of fasting is called Alternate Day Fasting. This method involves eating a regular diet of calories on one day and then restricting calories the next day (500-700 calories total).
The final type of fasting is called True Fasting. This is the total abstinence from food for longer periods of time.
If you have never fasted before, I would try restrictive time eating or alternative day fasting before you dive into true fasting. When you are ready to try true fasting, I recommend starting with a 24-hour period for men and 24 to 36-hour period for women. As you become accustomed to fasting, the length of fasting time can be increased.
The most crucial thing to remember about fasting is that you have to make sure you are drinking lots of fluids, preferably water, during the fast to prevent dehydration. In my own fasting, I allow black coffee but the purists believe it breaks the fast. Remember you are trying to restrict calories so you want to avoid any beverages that contain calories. Be patient with yourself as you figure out this process, you will be grumpy and hungry. You need to do what’s best for you!
Something to keep in mind during this process: most weight loss is water and can be misleading. Fasting will reset your metabolism for future weight reduction so it’s important to stick with it. Fasting has been practiced for 10,000 years and is safe and effective. In my opinion, this
is the one of the healthiest eating methods and I recommend it to all my patients.
Give it a try and let me know what you think! As always, if you have questions about fasting or anything related to your health please don’t hesitate to reach out!
Cheers to a happy, healthier you!