Intermittent fasting (IF) has been around since the time when our Paleolithic ancestors walked the earth. They didn’t have grocery stores, refrigerators, restaurants, microwaves, or convenience stores. Nevertheless, they were able to overcome periods of famine.

How on earth did they do it?

Well, it certainly wasn’t by eating five to six small meals every day. Instead, our ancestors naturally used intermittent fasting. Of course, they didn’t know they were doing this. And, frankly, they didn’t have much of a choice. Food had to be rationed. They had to adapt. So, they likely ate about twice a day.

The point is that our bodies are designed to withstand periods of famine. That’s why the body wisely stores any excess food in the form of fat to be used later. So, you see, intermittent fasting is literally as old as least the human race. It’s natural. It’s what your body is designed to do.

Unfortunately, most people today aren’t familiar with the concept of intermittent fasting. One of the reasons for this is that most developed countries have access to more than enough food. In fact, most of us wouldn’t know serious hunger if it jumped up and smacked us in the face.

It doesn’t help that every year there’s another new diet that’s “guaranteed” to work. After failing too many times with “modern” diets, people eventually stop looking and give up. They feel hopeless.

But the truth is seldom complicated. Often, the simplest and most natural approaches work best. They’re even sustainable without super-human willpower or discipline.

Intermittent fasting is quite simple. In this article, you’ll get a solid introduction to intermittent fasting. And who knows? Maybe intermittent fasting will help you to finally lose that stubborn and unwanted fat, stay in shape year-round, and eat without juggling five to six meals each day. Interested?

What Is Intermittent Fasting

Simply put, intermittent fasting is a way of eating. It involves fasting for periods of time. Fasting intervals can take place every day or one or two times a week. 

The “Skipped Meal” Perspective

Another way to look at intermittent fasting is to see it as deciding ahead of time to skip certain meals. That said, many advocates of intermittent fasting choose not to look at it as skipping meals. Instead, they see it as providing two windows:

1. An eating or feeding window
2. A fasting window

Looking at intermittent fasting that way, you don’t skip any meals. Instead, you simply bunch all of your meals into a smaller “eating window.” However, ultimately, you end up eating less. We’ll discuss skipping meals, particularly breakfast, later in this article. For now, just know that IF is simply a way of eating that involves eating only during a certain “eating window.”

Not A Diet At All

Of course, any time “eating differently” is discussed, some people ask, “is it a diet?” Well, no. Intermittent fasting is not a fad diet or any other type of diet. Intermittent fasting is not a diet because it doesn’t tell you what you can and cannot eat. In fact, intermittent fasting doesn’t tell you when to eat either. Instead, you choose your eating and fasting windows based on your lifestyle, schedule, and liking.

No Starvation Or Calorie Restriction (CR)

Furthermore, intermittent fasting is not a form of starvation, nutritional deprivation, or calorie restriction (CR). It’s not starvation because you are able to eat during your chosen eating or feeding window. It’s not calorie restriction (CR) because calorie restriction requires you to count calories and eat a restricted number of calories every day. As you’ll learn, intermittent fasting doesn’t tell you how many calories to eat at all.

So, Can You Eat Whatever You Want? Are Free Days Allowed?

Yes. In fact, many people who use intermittent fasting get great results without changing what they eat. And, of those people who choose to eat more healthily, many do choose to enjoy a “free day.” Free days are chosen days, usually once a week, during which any type of food goes. Some people take this day to enjoy rich foods and desserts.  Starvation and calorie restriction don’t allow for such freedoms, flexibility, or opportunities.

I’m not going to sit here and tell you whether or not having a cheat day is a good idea. You’re a grown-up and you can make your own decisions. Personally, I don’t have cheat meals, free days, or whatever you want to call them. I simply eat paleo or I don’t, always trying to make the best food choices for my health in whichever situations I find myself. Instead, I always prefer to promote food quality. IF, coupled with a paleo approach, might just be a match made in heaven.

Now that you understand what intermittent fasting is and is not, you can move onto understanding some of the benefits it offers.

The Benefits of Intermittent Fasting

Intermittent fasting comes with two main kinds of benefits:

1. Lifestyle benefits
2. Physiological and health benefits

As our lives, societies, and the world in general become more hectic and demanding, simplifying any area of your life is a good thing. And that’s exactly why more people are adopting intermittent fasting.

Here’s a short list of intermittent fasting lifestyle benefits:

• Flexibility
• Adaptable to almost any “diet”
• More simplified days
• Less time eating
• Potentially less money spent on food
• Simple and consistent eating schedule
• No more struggling to eat five to six meals every day
• Freedom from having to eat all the time
• Lessens the need to snack
• Opportunity to enjoy eating again
• Ability to eat as normal
• More daily energy
• Better mental focus
• No need to lose weight for special occasions or summer

And now for a list of some intermittent fasting physiological and health benefits:

• Promotion of weight loss
• Fat breakdown
• Ketone production
• Enhances muscle-building
• Promotion of better insulin sensitivity
• Reduction in blood glucose and insulin levels
• Increased growth hormone (GH) secretion
• Increased liver glycogen breakdown
• Potentially slower aging process
• Correlation with reduced colon cancer risk in men
• May protect against Alzheimer’s and Parkinson’s

When you consider the lifestyle, physiological, and health benefits of intermittent fasting, it’s easy to see why it’s becoming more popular.

Nevertheless, there are two sides to every coin. As with anything, intermittent fasting does have its cons for some people.

Intermittent Fasting: The Cons

In order for you to gain a complete perspective on intermittent fasting, you need to know what drawbacks it comes with. Many of these cons will fall into two categories – those associated with daily intermittent fasting and those associated with weekly 24-36 hour intermittent fasting. Some cons fit into both categories.

The cons for daily intermittent fasting include:

• Can pose challenges for people whose lifestyles demand a constant intake of high-calorie meals
• Short initial period of hunger until the body adjusts
• May not be suitable for people with blood sugar regulation issues, hypoglycemia, or diabetes (check with your doctor if you fall into this category)

The cons for weekly 24- to 36-hour intermittent fasting include:

• Some people seem to be more susceptible to overeating or binging after a longer fast
• Longer fasts can place the body under a bit of stress, so this might not be suitable for individuals with serious health concerns, blood sugar issues, or chronic stress in their lives (be sure to get your doctor’s approval if you suffer from any of those issues)
• Can be challenging for folks who have highly active lifestyles or people with high-calorie demands
• Twenty-four or more hours without food can seem like an eternity for some people, so this extended period of fasting can be more challenging to adjust than daily intermittent fasting

Many of these cons are temporary and usually subside as you move further into the intermittent fasting lifestyle. Strategies for eating, timing workouts, and handling hunger will be discussed later in this article, so keep reading!

Now that you know the most common pros and cons of intermittent fasting, let’s move onto finding out how it works.

Intermittent Fasting: How Does It Work?

To understand how intermittent fasting works, you need to know what the body does when in a fed state (aka when you just got your grub on).

When it’s being or after it is fed, the body produces insulin, so that blood sugar levels remain safe. Insulin is a hormone that transfers excess blood sugar to muscles and the liver, and into fat cells. Insulin therefore increases the amount of fat that’s stored by the body.

Eating six small meals each day means that insulin is released over a period of about sixteen hours for most people. That’s sixteen hours of insulin storing fat a day.

Intermittent fasting allows for a much smaller eating window. With the standard intermittent fasting eating window ranging anywhere from five to eight hours, insulin is only storing fat for five to eight hours, instead of for sixteen hours. That’s a big difference. 

It’s like flipping off the body’s fat storage ability for most of each day, allowing your body to actually use stored fat for energy and fuel. If that happens, you might end up losing fat or weight. 

So, that’s the quick and dirty version of “how intermittent fasting works.” Next, we’ll discuss eating.

Eating + Intermittent Fasting

As mentioned earlier in this article, intermittent fasting is not a diet. Therefore, you can continue to eat whatever you were already eating before incorporating intermittent fasting into your lifestyle.

This doesn’t mean that intermittent fasting is a license to eat crap. Every person should make continued efforts to tweak their food choices for increased energy, health, vigor, and longevity. That’s a no-brainer.

Intermittent training doesn’t tell you what to eat. However, we obviously recommend combining intermittent fasting with a paleo approach to nutrition. That said, let’s have a look at what an eating/fasting schedule might look like for someone enjoying the intermittent lifestyle.

Examples of Daily Intermittent Fasting

You can see a bunch of in-depth examples of IF here.

Daily intermittent fasting typically lasts between sixteen and twenty hours. So, for someone who’s chosen a lifestyle of daily sixteen-hour intermittent fasting windows, a couple of days might look like this:

Monday

• Last meal by 6:00 pm
• Fast from 6:00 pm until Tuesday

Tuesday

• Awake/continue fasting upon waking up
• Break fast and begin eating at 10:00 am
• Eat during eight-hour eating window of 10:00 am. to 6:00 pm
• Rinse and repeat

Examples Of Weekly 24 To 36-Hour Intermittent Fasting

Weekly twenty-four- to thirty-six-hour intermittent fasts are done once or twice each week for a period of twenty-four to thirty-six consecutive hours. So, for a person who does a twenty-four-hour intermittent fast once per week, a fasting/eating schedule might look like this:

Monday

• Last meal by 6:00 pm
• Fast from 6:00 pm until bedtime at 10:00 pm
• Sleep and fast from 10:00 pm to 6:00 am

Tuesday

• Awake/continue fasting until 6:00 pm
• Eat as usual (or whenever) until next Monday’s fast
• Rinse and repeat

A person can begin fasting at whatever time is best for them, whether they’re doing a sixteen-hour intermittent fast or a twenty-four- to thirty-six-hour intermittent fast.

How to Get Started with Intermittent Fasting

If you’d like to begin intermittent fasting, it’s a good idea to get clearance from your doctor first, especially if you have any health issues. That said, the following checklist should help anyone get off to a great start with intermittent fasting:

• First, decide which type of intermittent fasting you’d like to do. Remember, there’s daily intermittent fasting and weekly twenty-four- to thirty-six-hour intermittent fasting.
• Second, look at the fasting/eating illustrations above to get an idea of how you might map out your fasting windows and eating windows.
• Third, define your intermittent fasting period and it’s accompanying eating or feeding windows.
• Fourth, commit to getting between seven and nine hours of sleep every night. Adequate sleep curbs hunger and is vital to your health and recovery from exercise.
• Fifth, enjoy water, coffee, or tea anytime, even during your fasting periods. Drink as much as you like. Staying well hydrated helps with hunger and comes with a long list of health benefits.

That’s pretty much it. All you have to do is fast during your chosen intermittent fasting period (for example, 6 pm to 10 am) and only eat during your eating or eating window (for example, 10 am to 6 pm).

Whichever type of intermittent fasting you choose, feel free to gradually work your way up to the standard fasting periods. For example, if you opt for daily intermittent fasting of sixteen hours, you might start by doing only fourteen hours until you get the hang of it. Likewise, with the weekly twenty-four- to thirty-six-hour intermittent fasting, you might choose to begin with an eighteen- or twenty-hour fast and work your way up to twenty-four- to thirty-six-hour fasts each week. The choice is yours.

How to Handle Hunger on Intermittent Fasting

Daily intermittent fasting actually enables the body adapt to its fasting windows because of the pre-determined, consistent daily eating/feeding windows. The body actually adapts to this type of fasting much easier and much more rapidly than most people would imagine. But you still may be wondering, “what can I do to alleviate hunger until my body gets used to fasting?” OK. Good question.

Here’s a list of things many people do to alleviate hunger when they fast:

• Keep and stay busy
• Drink plenty of water (64 to 100 ounces)
• Drink coffee (black) or tea (unsweetened)
• Engage in physical activity or exercise
• Get a minimum of eight hours sleep each night

Also, it’s important to remember that your own version of hunger is the result of your eating habits and lifestyle.

Providing your body with a consistent time to eat each day allows it to quickly get use to fasting. Your body can acquire any new habit as long as there’s consistency. Plus, remember that this is how our ancestors ate for years. It will be very easy for your body to snap back into its natural eating state.

Should You Skip Breakfast while Intermittent Fasting?

With daily intermittent fasting, it seems like breakfast has to be skipped. However, breakfast is simply pushed back a bit instead. Breakfast is any meal that “breaks” your “fast.” So, technically, your first meal of the day, whether it’s at 10:00 am or 2:00 pm, is breakfast. You’re not skipping it; you’re delaying it a bit. So, you’re still enjoying the most important meal of the day.

What Do You Do About Exercise while Intermittent Fasting?

It’s generally recommended that fasters work out, train, or exercise in a fasted state. Many of those who do the longer fasts like to schedule their workouts or training off days to coincide with their fasting periods. 

Now, the next question you might ask is “don’t I need to eat to provide energy for my workout?” Whether it’s doing resistance training, high-intensity intervals, or cardio, the human body is capable of producing the necessary energy to get through any normal workout or exercise routine.

The key to exercising or training in a fasted state is to schedule your eating window to follow your workout. However, some people find this too difficult. And instead of abandoning intermittent fasting, they simply schedule their workout as close as possible to their eating window.

For those people looking to shed fat, the consensus is that it’s best to do resistance, body-weight, or higher-intensity intervals in super fat-burning workouts. Lower intensity, longer sessions of cardio have been shown to increase hunger and appetite and burn less fat than higher intensity forms of exercise.

So that’s it.

• Train in a fasted state
• Incorporate higher intensity exercise, resistance, or body-weight workouts into your day. 
• Schedule your eating window so that your first meal (the one that “breaks your fast”) is your post-workout meal.

Intermittent Fasting: What To Expect

Every person and every body type is different. Results vary. Also, the results you get will depend on your goals.

• Fat loss
• Muscle gain
• Better health
• Improved sports performance

Additionally, you have to take into consideration individual factors.

• Body-composition (body-fat percentage)
• Insulin resistance
• Eating and nutritional habits
• Type and frequency of exercise
• Daily lifestyle

Nevertheless, it seems like more and more people are seeing positive results and benefits from simply incorporating intermittent fasting into their lives, without changing anything else. The only way to tell what intermittent fasting can do for you is by starting, monitoring your results, and making adjustments along the way.

Remember: If you have any medical conditions or health issues, get your doctor’s approval before making changes to your eating habits or activity levels.

Photo credit: Keoni Cabral, espensorvik, Karrie Nodalo, andronicusmax, Ryosuke Sekido, and Didriks