So, in this article I want to go over what it is, and variations that exist and maybe more importantly, what it isn’t.

So read on for an in-depth explanation of Intermittent Fasting.

The Basics:

Fasting

fast  [ fast, fahst ]

verb (used without object)

1. to abstain from all food.
2. to eat only sparingly or of certain kinds of food, especially as a religious observance.

This means, if you are consuming protein shakes, BCAAs, cream in your coffee, or small meals, you are not fasting.

To be fair, there are several things considered “safe” to consume during a fast that will not break a fast.

Click Here for my post on Foods that do and don’t break a fast.

Intermittent Fasting Protocols

There are several ways to “do” Intermittent Fasting. These would be considered the IF Protocols, and the main difference between each is the duration and/or timing of the feasting window. I’ll explain.

16:8

The most common protocol for IF is probably 16:8. This means you would fast for 16 hours, and feast for 8 hours.  Generally, the time of day that you eat doesn’t matter. Therefore, you can slide your 8 hours wherever you want. The important part is that you have 16 hours of no eating. Most people get 6-8 of these during sleep.

So, you can do your 8 hours from when you get up to 8 hours later, you can start it at noon and go till 8… Basically, you can do whatever you want regarding the TIME you eat, but the duration of your eating window stays at 8 hours.

And for the record, if you eat at noon, and start eating at 8, then your feeding window would technically be longer than 8 hours because you’d be eating still, past 8. This means that generally, most IFers would likely start eating closer to 7 to be done eating by 8 and start their fasting window. So, you can see already that the EXACT timing of fasting/feasting isn’t precise. The good news? It doesn’t have to be.

20:4

Sometimes this is called the “Warrior diet”. It’s a 20-hour fasting window, with a 4-hour feeding window. This is NOT for the beginner faster. In fact, starting fasting can be ….. Challenging.  Click here for tips on how to get started Intermittent Fasting.

Typically, the IFer doing  20:4 fasting would eat only 2 meals during their 4-hour feasting window.  As you can imagine, depending on the caloric needs of the person, those meals could be rather large or super dense in calories. Granted, MOST of us do not need to consume very large quantities of calories.

But given the short window to get the essential nutrients, it’s often not recommended for high-performance/elite athletes to practice IF. Exceptions could be during an off-season, when the athlete is dialing back on training, focusing on recovery and fat loss.

18:6

This bridges the gap between 16:8 and 20:4. It would be slightly easier to do than the 20:4 and slightly harder than 16:8. But it can be quite common, especially if you’ve been 16:8 for a while, but can’t quite stomach the idea of packing all your calories into a short 4-hour window. Eating for 6 gives you time to have 2 larger meals and a small snack to get all your calories in.

One Meal a Day (OMAD)

OMAD is exactly what it says. It’s eating one meal within a 24 hour period. As with the 20:4 fasting, you can imagine that getting all the calories you need in that one meal… well,… let’s just say, your body will need to adapt…

Alternate Day Fasting

Alternate day fasting would be eating during one 24 hour period and not eating for the next 24 hour period. There are quite a few variations that could be taken on this. The first, would be to eat relatively regularly during the feeding day (so breakfast, lunch, dinner over an 8-12 hour period).  The other would be to keep the feeding window shorter on the feeding day (4-8 hours of feeding) and lengthening the fast.

There are benefits to doing longer fasts. However, if these benefits are what you’re after, it is not recommended to do them “all the time”.  Maybe do a 24 hour fast once a week at most. And anything over that (36 or 48-hour type fasts) only once a month or less.

Time-Restricted Eating (TRE)

In my mind, time-restricted eating is just another name for intermittent fasting because essentially in IF you’re restricting the time you’re eating.  But in some TRE protocols, you actually eat only during a very specific period of time. For example, first thing in the morning till 8 hours later…

Circadian Rhythm

This fast is supposed to align with your natural circadian rhythm. The fasting period is when the sun is down. You eat when the sun is up. If you’re practicing this method of fasting, you would notice that your eating window would be shorter in winter and longer in summer.  You might also notice its opposite of the fast Muslim practitioners do during Ramadan.

What protocol is best?

Well, that largely depends on you. You must consider your goals, your lifestyle, your current eating habits, your family, your culture, your schedule, and your body.

What Intermittent Fasting Isn’t

I absolutely have to put a blurb in here about what isn’t IF that might get labeled as IF.

Very Low-Calorie

On several occasions, articles have been written regarding studies on IF with mixed results. Generally, IF is considered to be incredibly beneficial (if one of the above protocols is used). However, some studies have called it intermittent fasting, but instead of actually fasting during the fasting period, they allowed the study participants to consume food. Generally, the caloric consumption of that food was a very low-calorie diet.

Very low-calorie diets gained some press because they were shown to increase longevity. However, they are incredibly hard to sustain. By eating even a little bit of food (calories) you signal your body that it’s “food time” and your hormones will kick into gear and take over for you, making you hungry.

Whereas, if you stick to a fasting protocol, the hunger hormones actually decline over time.  This means, if you are actually fasting (not eating a tiny bit of food), over time you will feel less hungry.

There are a whole host of chain reactions in your body that happen when you eat.  And some of those turn off the benefits received from the fasted state. So, if you think you’re fasting, but you’re having sugar or cream in your coffee, or alcohol  after dinner, your body isn’t fasting. And the benefits are likely negated.

“Blank Check”

Also, Intermittent fasting isn’t a blank check to “eat whatever you want and whatever quantities you want” during your feasting window. The general energy balance equations absolutely still apply. (ie. If you eat more than you burn, you’ll gain weight, and if you eat less than you burn, you’ll lose weight). Too many people think that they can go all wild on food during the feasting window and still lose weight.

Metabolism Increase

Yes, IF grants some additional fat-burning benefits. But it doesn’t make you burn more calories (increase your metabolism). (Not like exercising or packing on muscle might.) It just helps change where you get your energy from. If you are fasting, you are more likely to tap into your own body fat stores to get your energy. And, there’s a big boon with fasting that your muscle mass is generally NOT used. Your body prefers fat for fuel anyway, and even at 5% body fat, you’d still have plenty of fuel on you to live comfortably for a short fast.

What if the Protocols mentioned don’t work for me?

That’s great! You mentioned 7 IF Protocols, is that it? What if one of those doesn’t work for me?

The good news is that those 7 protocols are just the “most common” ones. The beauty of IF is that it’s super flexible. If 17:5 is your style, do it. If you’re starting out and 14:10 works for your schedule, go for it.  Maybe you’re a 16.5:7.5 IFer. Whatever. The only real rule is that when you’re fasting, you’re not consuming calories.

So there you have the definition of intermittent fasting, and what it isn’t. As well as some protocols and their definitions to get you started.