The Power of Fasting for Health + Side Effects

Move over breakfast, fasting is here to stay.  Sorry, Kellogg’s and Nabisco. Research in the world of fasting is becoming robust for helping with many aspects of health.  The power of fasting can benefit everything from your weight and inflammation to reducing cancer risk.

As you will quickly find out, fasting is definitely not for everyone and should be done with great care.  In this blog, I will share with you some types of fasting, my personal experiences with fasting, benefits, risks, and pitfalls to avoid.

Fasting History

Fasting actually isn’t a new concept at all, but it deviates from the common dogmatic way of “eating until full” every day, or eating whenever hungry.  This is the common mode of eating today in Western culture.

Fasting has been done for religious reasons and personal health reasons since the dawn of humans. Fasting also has been done by most humans in history inadvertently due to a lack of food supplies.

The exceptions would be kings and royalty who always had food at the ready.

Who Should Fast and Who Should Avoid Fasting?

The potential health benefits of fasting are broad; it can have a “cleansing” effect by dampening down inflammation, may reduce the risk of diabetes, reduce body weight, and more.

When done properly, fasting may be what the doctor ordered. Read a fast mimicking diet review I wrote here.

Some people, such as children and adolescents and those on medications that affect blood sugar, should not try fasting without medical supervision.

Fasting should be done in the context of a usually balanced and healthy diet. If this isn’t you, work on getting your diet balanced first.

Who Fasts?

We all fast, whether we want to see it that way or not.

Our body goes through a period of rest, or sleep, where we don’t eat.  We might inadvertently do it for an extended period when we are sick or low on money to buy food.

Certain fasts as described below, extend that period of fasting in a variety of ways.

Related post: 13 Interesting Benefits of Fasting for Gut Repair

Types of Fasting

Many types of fasting exist; in fact, there are infinite ways to “fast.” Here are some of the most common.

Water Fasting

Water fasting is exactly what it sounds like: taking in water only for a determined period of time.  Some people do it for days in a row. This is a type of fast to ONLY do under complete medical supervision, and as you might imagine, can be very unpleasant.

Side effects are sometimes large, ranging from fatigue to pain and digestive discomfort [R].

However, water fasting doesn’t seem to have as severe of side effects as some might imagine, at least in research.  A large body of data collected only saw 1 hospitalization and no deaths.

Research isn’t without its flaws, however, so I don’t recommend this form of fasting, mostly because it can be quite unpleasant.

Intermittent Fasting

Also known as time-restricted fasting: intermittent fasting is the most popular form of fasting because it is the easiest to follow.  Technically speaking, all types of fasting are intermittent.

How does one intermittently fast? Simply limit the number of hours of eating during the day.  I do this a few days a month or more, without much difficulty at all.

All fasts are technically intermittent, but the following kinds are quite popular because of their ease of implementation.

The 16/8 method:

This is popular, with 16 hours a day of fasting and 8 hours of eating span is allowed. No other requirements.

The 14/10 method:

Very similar and slightly easier to follow to the 16/8, with 14 hours a day of fasting and 10 hours of eating.


A vegan-style fast with 10% of calories as protein. It also is lowish calories for 3-5 days, between 800-1000 calories per day.  Following the 3-5 days, people resume their normal eating schedule.

The reduction in protein for a short period of time is done because it can help shut down growth factors that drive inflammation.

In a fascinating study of 100 generally healthy people, simply following a fast-mimicking diet for 5 days out of the month reduced blood pressure, cholesterol, inflammation, body fat, body weight, and fasting glucose compared to “regular” eating [R].

Fast-mimicking diets also may help repair and replace damaged cells in the setting of autoimmune diseases, according to early data [RR].

Religious Fasts

Every religion has fasting in some way, shape, or form.  Food deprivation for short periods of times is thought to bring about a closeness to a higher power and enhance the spiritual experience.

It is a form of sacrifice as well and a way of honoring a higher power.

Health Benefits of Fasting

Regardless of the type of fasting, they all seem to affect similar pathways in the body with the end result of less inflammation.  This is how fasting potentially reduces the chances of many diseases.

Here is the irony:  Fasting works better (easier) for a person who has a well-balanced diet. It is much easier to implement for people who eat pretty well at baseline.

Fasting may help with many conditions, especially the following:

  • Extend lifespan and healthspan [R]
  • Rejuvenate pancreatic cells [R]
  • Reduce body weight and body fat [R]
  • Heart benefits by reducing inflammation [R]
  • Reduce triglycerides and cholesterol [R]
  • Reduce diabetes symptoms and numbers and improve insulin resistance [R]
  • May reduce cancer risk [R]
  • Increase fat burning [R]

In a very large observational study, fasting greater than 13 hours per night resulted in a reduced risk of death from breast cancer [R].

Further,  intermittent fasting in this same study resulted in improved sleep and improved markers of blood glucose (Hemoglobin A1C).

Fasting later in the day may prove as effective or more effective than skipping breakfast.

People who ate less than 30% of their calories in the evening had reduced inflammation markers and reduced glucose markers  [R].

The TYPE of food eaten late at night may also matter.  Those who ate fruits and vegetables didn’t have an increased risk of breast cancer, but those eating starchy foods did [R].

The Fasting Experience

It is important for healthcare providers to be open-minded and as such, open-minded to trying fasting.  What better way to learn about it than to do it?

I read a LOT of research, and  after all these years, I know that research can never describe the human experience. That is why I am sharing it here with you today. After all, healthcare is both an art and a science.

First, a little bit of information about me.  I tend to be lean and thin, regardless of what I eat, so a fast may affect me differently than someone who has a lot of extra pounds.

I have an ectomorph-type build, and have a hard time putting on muscle.  This is a sign that prolonged fasting should never be in my repertoire. If this describes you, please also avoid extended fasts.

My first intentional fast was the fast-mimicking type.

What surprised me?  It was quite easy to follow, up until the evening of the second day. I started getting a pretty bad headache at that point, so I ended my fast at 2 days.

I felt pretty good throughout it up until that point, and did, in fact, feel cleansed and quite healthy and good.

The first time I followed a fast-mimicking diet, even for just 2 days, I had lost about 3 lbs, which for me, is a lot.  I kept the weight off despite returning to my normal eating schedule and without even trying.

It really isn’t even that restrictive:  1000 calories a day or slightly less for a few days.  I loaded up on copious amounts of vegetables during my fast since I need to eat real food.

The downside of fast-mimicking for me

I had a noticeable loss of my arm muscle mass. I didn’t gain it back easily either;  I always struggle to hold on to upper body strength.

Here are the variables that research ISN’T measuring about fasting. How do I know?  I experienced them.

Fast-mimicking had some untoward effects on the psychology of eating for me for a while. For example, it made me a little preoccupied with eating when I went back to a normal eating schedule.

This could be a problem for those predisposed to eating disorders.

Some people may waste muscle.  I lose muscle really easily, especially in my upper extremities.

Women may want to avoid fasting while having “that time of the month.”

Ever heard of the slang term hangry?  This is anger due to hunger.  PMS hormones may amplify these feelings when fasting.

I recommend that women, if trying intermittent fasting, stick to trying it first in the early part of their menstrual cycle, and try it if and only if their baseline diet is high-quality.

The plus side of the fasting for me?

I lost the weight and never gained it back.  Never. And I did gain my muscle back, slowly.

Here’s what I do now for a fast. I only do this occasionally because my body weight is on the low-ish side anyway.  I do this a couple of days a month. I eat my protein later in the day; I can’t go a whole day without some animal protein from what I experienced with the vegan-style of fasting.

My Schedule for Intermittent Fasting

Wake up

Hydrate with water or herbal tea

10 AM

Some coffee or tea

1 PM Lunch

Heaping plate of green veggies, cabbage, broccoli, etc. Sunflower seeds and olive oil vinaigrette

More hydration

3 PM

Kombucha with chia seeds

Dinner: 6 pm

Normal dinner with a good amount of protein, at least 4 oz (eggs, chicken, fish, meat, etc), fruit, and vegetables.  I add a starch too, like brown rice or potatoes.  I eat until I’m very content.

Easy. Pretty nutritious too.

I would love to be able to try the fast earlier in the evening, but my life is way too busy at that time of day.

The evening is the part of the day when I have a chance to be physically active.  I need the calories later in the day to stay balanced emotionally and for adequate sleep, especially when I exercise.


Want more tips about how to fast the healthy way or learn more?  Contact me.

As always, make sure you inform your healthcare provider BEFORE starting any new health regimen.

The information on this website has not been evaluated by the Food & Drug Administration or any other medical body and is shared for educational purposes only. Consult your doctor or healthcare provider before making changes to your supplement regimen or lifestyle.

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