An Introduction to the Hottest Nutritional Theory on the Interwebz
INTERMITTENT FASTING may well be the most discussed dietary concept on the Internet of the last decade.
Like many other “breakout” diets, intermittent fasting (IF) is growing by leaps and bounds; however, unlike most of the other diets, IF is gaining ground despite that the practice challenges many long-held assumptions about nutrition.
In fact, practicing IF forces you to eat in direct opposition to those assumptions, and that—along with the results—it what’s generating all the buzz.
Before we get into the why and the how let’s first discuss the basics of the what.
(NOTE: Don’t feel like reading? No problem. Scroll down to the bottom; I’ve got a short video completely covering everything in the post.)
The most accurate definition is the simplest one: IF is merely alternating intervals of not eating (fasting) with times where you are allowed to eat.
Or, to use IF parlance, you alternate a fasting period with a feeding window. The length of a fast depends on which intermittent fasting protocol you select—and there are several.
Each method of intermittent fasting will be discussed in a later article, but for now, it’s enough to mention that the differences come from expanding the fasting window. The fasting period on specific plans can range from 16 hours all the way up to 36 hours (with several stops in between), and each of those specific plans will have benefits.
It’s also important to note that every one of us does some form of fasting, whether we realize it or not. The least technical-while-still-being-accurate definition of fasting is simply “not eating,” so anytime you’re not eating, you’re fasting.
Most of us aren’t on a structured timetable of meals where the window of fasting is constant, so rather than fasting intermittently, we’re fasting haphazardly—and there’s no benefit there.
The exception for most people is sleep. When you’re sleeping, you’re fasting; therefore most of us have a fairly rigid fasting period of 6-8 hours per night until we eat in the morning. It is for this reason, by the way, that our morning meal is called “breakfast,” as you are literally breaking your overnight fast.
Which brings me to my next point.
Breakfast is sort of a hot topic in the IF world, and in fact seems to be the first point of contention for people looking in on intermittent fasting from the outside. Don’t we need breakfast?
Intermittent Fasting proponents tend to say no…which flies in the face of much of the dietary advice coming from every authority from Registered Dietitians to MDs. IF peeps don’t give a shit, though, because these dudes hate breakfast.
Here’s why: for years, we’ve been told that breakfast is the most important meal of the day. In fact, many people are often scolded by their physicians for skipping breakfast—particularly people who are embarking on a plan to lose weight.
There is some credence here, by the way: a study conducted in 2008 showed that participants who ate a calorically dense breakfast lost more weight than those that didn’t. The espoused theory for the results was that the higher caloric intake early in the day led people to snack less often and lowered caloric intake overall.
The value of that study has been questioned for many reasons, not the least of which is that despite the fact that roughly 90% of Americans eat breakfast, close to 50% of Americans are overweight. If eating breakfast is the first step to weight loss, then clearly something else is going wrong.
More evidence seems to support the breakfast idea, though. There are some epidemiological studies that show a connection between skipping breakfast and higher body weight.
Of course, proponents of the breakfast theory are quick to suggest that most people are simply eating the wrong breakfast, like quick n easy meals like Danishes and doughnuts, which can lead to weight gain.
However, the crux of the breakfast study, ultimately, is a larger breakfast tends to lead to a lower overall caloric intake. That is, the argument for a larger breakfast ultimately boils down to energy balance; if that study is reliant on the position that weight loss comes down of calories in versus calories out, then the makeup of the food shouldn’t matter. If we’ve learned anything from Mark Haub’s Twinkie Diet, it’s that you can eat garbage and lose weight; clearly, something else is going on.
As a very basic note on what this is and why this matters: the more sensitive your body is to insulin, the more likely you are to lose fat and gain muscle. Increasing insulin sensitivity almost always leads to more efficient dieting.
Getting back to it, supporters of eating breakfast declare that as insulin sensitivity is higher in the morning, eating a carbohydrate-rich breakfast is going to have the greatest balance of taking in a large amount of energy without the danger of weight gain.
This brings us back to IF. You see, insulin sensitivity isn’t higher “in the morning”; it’s higher after the 8-10 hour fasting periods you experience if you sleep. Or more specifically, insulin sensitivity is higher when glycogen levels are depleted; as liver glycogen will be somewhat depleted from your sleeping fast.
Intermittent fasting takes that a step further: it seems that extending the fasting period beyond that 8-10 hours by skipping breakfast (and therefore further depleting glycogen) will increase insulin sensitivity even further.
Insulin sensitivity is also increased post-exercise (due to further glycogen depletion in addition to other mechanisms), and so I feel it makes the most sense to compound benefits by training in a fasted state and then having a carbohydrate meal or shake, maximizing the already potent effect of your para-workout nutrition.
Ultimately, this all means that there’s nothing special about breakfast and no need to eat first thing in the morning—the first meal you eat to break your fast will be exposed to the benefits of increased insulin sensitivity.
On the other hand, I’ll take my tongue out of my cheek long enough to say that there’s nothing inherently evil about breakfast, either; that is, even if you practice some form of fasting, you can still eat breakfast. Remember, the more important part is the length of the fast, not the time of the fast. Skipping breakfast just happens to be the easiest way to implement a fast.
A discussion that mentions skipping breakfast—or any meal, really—will invariably lead into a discussion of meal frequency, which leads me to my next point.
And now we come to the last and perhaps most important point.
It seems that over the past 15-20 years, hundreds of diet books have been printed, and no two were identical. In fact, some of them have been in direct opposition to one another.
Calorie-restrictive plans like Weight Watchers certainly don’t agree with plans like the Atkins diet, the first iteration of which allowed dieters to eat all they want, as long as they kept carbs low.
Similarly, carb-conscious plans generally call for products like yogurt or cottage cheese to be used as portable sources of protein, but many plans reject dairy products altogether.
Despite the incredibly disparate natures of so many of these diets, the one thing that has been consistently suggested in most books published over the past 20 years is the frequency of meals.
If you’ve read a diet book, seen a nutritionist, or hired a personal trainer at any point during that time, you’ve probably been told that in order to lose weight, you need to eat 5-6 small meals per day. (Note: this suggestion is sometimes phrased as “3 meals and 2 snacks.”)
This style of eating, commonly referred to as the frequent feeding model, is popular with everyone from dietitians to bodybuilders and has been repeated so often for so long that it’s generally taken as fact.
Which it isn’t.
In fact, the reputed benefits of eating small meals more often have never been scientifically validated.
The first and most commonly cited of these is that eating frequently “stokes the metabolic fire.” Put less colloquially, the theory suggests that since eating increases your metabolic rate, the more often you eat, the more your metabolic rate will be elevated. That’s true, but it doesn’t lead to greater fat loss—in fact, it’s been scientifically borne out that there won’t be a difference at all.
When you eat, your metabolic rate increased because of the energy required to break down the food you’ve taken in. This is called the Thermic Effect of Food, or TEF. So, while you’re experiencing energy expenditure due to TEF every time you eat, the net effect is no different regardless of how many times you eat, as long as the total amount of food is the same.
You see, TEF is directly proportional to caloric intake, and if caloric intake is the same, at the end of the day, there will be no metabolic difference between eating 5-6 meals or 2-3. In fact, as long as the total calories are the same, you can eat ten meals or one meal, and you’ll still get the same metabolic effect.
A smaller number of meals obviously fits well into fasting protocols—if you are condensing the amount of time you’re “allowed” to eat into a small window of 4-8 hours, having more than 2-3 meals becomes impractical at best and impossible at worst. My clients who practice IF eat 3 meals (not counting a post-workout shake, which they consume on days they train with weights).
Obviously, above and beyond the debunking of long-believed myths, there are numerous benefits to Intermittent Fasting that make it so popular.
Firstly, as we’ve established thus far, people who practice IF eat less frequently. In addition to feeling hungry less often, and more full when they do eat, these people benefit in terms of practicality and logistics.
After all, eating fewer meals means fewer meals and/or buying fewer meals. In addition to saving you time (and, probably, money), this also means that you’re exposed to flavors less often, and are therefore less likely to get bored and eat something you shouldn’t.
We’ve also mentioned that eating less frequently tends to result in eating fewer calories overall, but that’s a pretty important point so it bears repeating: eating less frequently tends to result in eating few calories overall.
And speaking of caloric restriction: that brings us to another benefit. Intermittent fasting plans that require full-day fasting drastically reduce your calorie intake, so if you are using a style of IF which requires you to fast for 24 hours twice per week, you’re reducing your food intake by about 30%. It’s not hard to see how that would lead to weight loss.
Going a little further, by restricting calories, you’re forcing the body to look elsewhere than the gut for energy, which can encourage cellular repair. That is, a cell will turn to its own damaged proteins for energy. While that cycle would be bad in the long term, keep in mind you’re only fasting for “brief” periods; when you eat again the cell will use the new cell-stuff to replace the old cell-stuff that’s been consumed. All told, this phenomenon—which, again, stems from caloric restriction—can generally help prevent both disease and age.
For something more specific: one study out of the University of Utah showed that people who fasted just one day per month were 40% less likely to suffer from clogged arteries.
While there’s certainly a lot to be said for caloric restriction, it’s important to keep in mind that intermittent fasting isn’t just about eating fewer calories—there are also hormonal benefits that lead to improved body composition.
For starters, there’s the improved insulin sensitivity that comes with fasting, especially when paired with exercises, as we’ve covered; however, fasting has other hormonal benefits, including (but not limited to) an increase in the secretion of growth hormone (GH).
Growth Hormone has myriad benefits—a discussion of which in full is beyond the scope of this writing—but for our purposes, it’s enough to say that the more GH you produce, the faster you can lose fat and gain muscle. Additionally, GH tends to offset the effects of cortisol, which is (in part) related to belly fat storage; so it seems likely that fasting can help you lose belly fat, at least indirectly.
The most important thing to remember about Intermittent Fasting is that it isn’t a “diet” —it’s a way of eating, a nutritional lifestyle that will allow you to reach your goals in an efficient and convenient manner, and then hold onto your physique once you achieve them.
In addition to the hormonal benefits inherent in the practice, you’ll also feel more satisfied with your food, feel hungry less often, and probably save some money on food!
Moreover, you may live longer…if, you know, you’re into that. And if you are into that, I recommend you check out our guide on the best NMN supplements, an ingredient showing a lot of promise in reducing biological age.
So, even if you never try IF, you can at least appreciate that it’s forced the industry at large to re-evaluate the “truths” we tend to cling to.
Perhaps it’s for this reason that Intermittent Fasting seems to be generally received with appreciation and acceptance, while low carb diets, Paleo eating and the “Twinkie diet” all have people on both sides of the line either praising or lambasting them.
That is, Intermittent Fasting is well received once people see the research—and there’s a simple reason for that: it works.
Next time, we’ll discuss the various methods of intermittent fasting, touching on the theories and reasoning behind each protocol, as well as the fitness professionals popularizing each one.
UPDATE: Part Two: Intermittent Fasting 201, gives you a breakdown of the most popular intermittent fasting protocols.
And for the most popular questions regarding IF, check out this post covering Intermittent Fasting FAQs.
If you’re interested in the hottest Intermittent Fasting program on the web, check out my New York Times bestselling book, Engineering the Alpha – it contains ALL of these benefits and more.