The Skinny On Intermittent Fasting

What Works.

What Doesn’t.

“He who eats until he is sick must fast until he is well.”

-English Proverb

First, What Is Intermittent Fasting?

The term Intermittent Fasting (IF) is referring to a “dieting” technique where a person restricts calorie consumption for specific periods of time. In short, a person knowingly restricts eating, or drinking any beverages, containing calories during periods of “fasting”.

It’s important to note that Intermittent Fasting is not a “diet” but rather a technique used as an attempt to achieve health benefits including weight loss.

Today, Intermittent Fasting is often marketed as the “miracle technique” where one can eat “anything they want” and still lose weight. So, let’s dive in and learn more about Intermittent Fasting.

What Are The Alleged Benefits Of “IF”?

Weight loss

Lower bad cholesterol

Reduces insulin resistance

Promotes cellular repair

Increased energy

Managing or reducing the risk of Type 2 Diabetes

Protection against neurodegenerative diseases (Example Alzheimer’s, Parkinson’s, etc.)

Types Of

Intermittent Fasting

Time-Restricted Fasting

Time-restricted fasting is likely the most popular IF method.  This approach is carried out by eating and fasting during specific time frames each day. A person will consume their daily calories during their “eating window” followed by a period of fasting. 

For example:

The 16:8 time-restricted option allows you to consume calories during an 8-hour window of time. Followed by, a 16 hour fasting period. The established “eating window” time period is up to you. 11:00am – 6:00pm, 12:00 pm – 8:00 pm, etc.  Once your eating window closes, you then fast until your eating window opens the following day. 

16:8 is not the only time-restricted fasting option. Some people begin with a 12:12 window; 12 hour eating window followed by 12 hours of fasting. 7:00am-7:00pm, 1:00pm-1:00am, etc. 

The fasting ratio and eating window can be any timeframe that works best for a person’s schedule and lifestyle. Most consider this the simplest and most convenient IF method due to its flexibility and easy scheduling. 

Modified Fasting

This IF method is slightly more advanced than time-restricted fasting. It’s recommended to begin with time-restricted prior to attempting modified fasting.

This approach is carried out by eating normally for five days, followed by two fasting days (5:2). 

During the two day fasting period you are allowed to consume minimal calories; 500 or less per day. Whether you consume all 500 each day during one sitting or multiple, the choice is yours.

Alternate-day Fasting

This is an IF method which most people are familiar with, it involves alternating fasting and eating days. It’s also known as the “24 hour fast”.

This approach is carried out by fasting for a minimal 24 hour period any time during the week. Some people will push the fasting time to 36 hours however, 24 is the most commonly practiced.

Select the time period and day you will fast and only consume water for a full 24 hour period.   

The Science

What Does The Research Say? 

When it comes to dieting trends, a rule of thumb isn’t “trust but verify”, it’s actually “never trust, always verify”. Sure some things are safe to try and can work better for others but ultimately, scientific studies should be most heavily relied upon. You want to search for unbiased scientific research and review the results in great detail.

So does intermittent fasting research exist?…It sure does! 

Even better, the results are fairly positive as well. There is evidence suggesting that fasting during the night has an effect on lowering the risk of chronic diseases (cardiovascular, type 2 diabetes, and some cancers). Consuming calories during the earlier parts of the day also had an effect on weight loss. However, for those working night shifts, fasting during the day and a nighttime eating window had negative effects on all the risks mentioned above. 

Modified fasting studies have reported some positive benefits including significant weight loss and a reduction to fasting insulin levels however, the results are mixed from study to study. Research on alternate day fasting is extremely rare to find especially on humans. 

Most intermittent fasting research has been focused on time-restricted fasting. As time goes on, more research and their results are likely to be published.

Patterson, R.D., and Sears, D. (2017). Metabolic effects of intermittent fasting. Annual Review of Nutrition. 37:371-393.

Summary

In short, healthy periods of fasting can result in positive effects on your health. However, it’s important to remember, temporary behavior change produces temporary results. Despite IF is a dieting technique vs an actual diet, it’s still difficult to maintain on a regular and lifelong basis.

It’s no surprise our recommendation is to focus your energy on changing behavior in order to adopt a consistent, healthy eating style. You can choose to try a time-restricted fasting method but lifelong healthy habits result in the greatest long term benefits.

Limiting entire food groups, timed eating sessions, counting macros, the latest “diet” fad, etc. may temporarily result in positive change but are too complicated to maintain over a lifetime.

If You Choose To Try an IF Method: DO…

Consult your physician and determine if IF is safe for you.

Consume healthy foods during your eating windows; DO NOT consume "anything you want" (If that means unhealthy, empty calories.)

Drink plenty of water to flush your system and to keep you hydrated and regular.

Stop IF immediately if you start to feel a desire to "binge eat" your food.

Plan ahead so you can consume a healthy amount of calories during each eating window. DO NOT attempt to dramatically under eat while practicing IF.

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