A Breakdown of the Most Popular IF Variations
Today, we’re going to get in depth about the most popular Intermittent Fasting protocols. Before we begin, in the last article about intermittent fasting, I gave you a brief primer on the practice. In that article, we covered a definition of IF, as well as some of the general aspects of practice that are consistent with various types of IF.
To briefly summarize: intermittent fasting is the practice of abstaining from food for a predetermined period of time, generally in the range of 16-36 hours. The benefits of IF vary from hormonal optimization to hunger management and caloric reduction; which benefits are prioritized will be dependent on which “type” of IF you use.
In this article, I’ll give you a complete analysis of the most popular intermittent fasting styles currently discussed in the fitness world, benefits and drawbacks, as well as my own personal experience.
Given that the most obvious difference between each of these methods is the length of the fasting period, I’ve listed them in order of longest fast to shortest.
SUMMARY: The feast/fast model is my own small contribution to the world of intermittent fasting protocols, although its inception had nothing to do with the benefits of fasting.
When cheat days were a common dietary practice for me, it became apparent that while the benefits were clear in terms of fat loss and mental reprieve, the aftermath from the more extreme cheat days was unpleasant. A Sunday spent questing for caloric overload meant a Monday spent in the throes intestinal distress.
I’d come from the old school bodybuilding mentality of, “if you fall off the wagon, get right back on, immediately.” The conventional wisdom of the ancient Bro Gods intoned that you’d do more harm than good if you long deviated from your typical dietary intake, even on the heels of a cheat day.
After a night of eating pasta, ice cream, brownies, and steak–often, all at once–, force feeding myself a cup of oatmeal and four eggs was the last thing I wanted to do. And yet, for years, that’s exactly what I did.
After some time, I discarded the bodybuilding “rules” and started pushing my first meal of the day back by a few hours. Eventually, I stopped eating altogether.
My results, I am happy to say, improved. Thus was born the feast/fast model.
BENEFITS: When I started looking into fasting (mainly to justify my not-eating), I came across a few different reasons why the feast/fast worked so well; some had to do with fasting, obviously, but there is some stuff that has to do specifically with the cheat day as well.
Like any style of fasting, removing food for an extended period of time can lead to fat loss, because it often leads to lower caloric intake. However, a fast coming on the heels of a cheat day is somewhat more specific.
As I’ve written about this before, the abridged version:
Prolonged reduction of caloric intake results in downregulation or reduced production of a hormone called leptin. As leptin levels drop, so too does the production of thyroid hormones T3 and T4, resulting in an overall metabolic slowdown. Fat loss, itself being influenced by those factors, also slows down. As leptin levels are in large part dependent on caloric intake, the influx of a large caloric surplus–occurring in a “cheat”–bumps those levels up a bit, thereby increasing the rate of fat loss.
Scheduling a period of fasting subsequent to a cheat day, therefore, does two things:
While it is difficult to quantify the in-vivo effects of such practices without hormonal panels, the practicality of the feast/fast approach is unassailable. That said, while this was created in an effort to alleviate discomfort, it also happened to work in terms of enhanced efficacy.
DRAWBACKS: There are a few here.
There first is that in order for this to be applicable, you have to have a cheat day—can’t exactly do a feast/fast without the feast. Some people don’t like cheat days (I know, weird, right?). I made a pretty compelling argument for the inclusion of cheat days here, but if you don’t like them, you don’t have to use them.
From there, the main drawback is that you’re really looking at a 32-36-hour fasting period. If your last meal on your cheat day is before bed (assume 10PM) on Sunday, and you don’t eat at all on Monday, your first meal is breakfast Tuesday morning. For a number of people, this has proved to be a pretty difficult thing to do.
I believe that with some practice just about anyone can abstain from food for an extended period of time with little discomfort, but for a lot of people, the idea of going without food for a day and a half is a bleak proposition.
For these people, I let them keep the training wheels on for a few weeks: I’ll allow people a small dinner on Monday night, to take the edge off of the hunger. This won’t detract from any of the hormonal stuff, it just adds some calories where there weren’t any before.
HOW (AND WHEN) I USE FEAST/FAST: I am a big fan of cheat days, so I use this method nearly every week. I like my cheat days to coincide with Sundays—because, call me crazy, but I like wings and nachos when I watch football.
This means that Mondays, I don’t eat AT ALL. I think this is a good fit for most people – Monday happens to be the busiest day for most people (myself included), and so if ever there was a time where it helped to free up a few hours by not eating, this is it. Also, since people are busier, they tend not to realize they’re hungry. Overall, this is a fantastic combo that works very well for most people.
OVERALL IMPRESSIONS: Again, this is my method, so I can’t really be objective here, but it’s worked well for me in the past, and all of my clients who have tried it.
SUMMARY: A 24-hour fasting period is essentially what it sounds like: if your last meal is at 8pm on Monday, then you simply do not eat again (at all) until Tuesday at 8pm. This can be done 1-3 times per week, with 2 being the most common iteration.
It’s impossible to talk about 24-Hour fasts without talking about Brad Pilon and his book Eat-Stop-Eat, which is the definitive book on this style of fasting. ESE has been around for several years, but Brad continues to publish updated versions with more science whenever he can. It’s a well-researched book that also happens to be well-written.
Brad was one of the first people talking about IF, and his approach to it is one of “lifestyle, not diet.” Brad discussed much of this in an interview I did with him, which you can read here.
BENEFITS: The 24-hour fast works well for a number of reasons. The first of these is that it is easily adaptable to any lifestyle, and it’s very hard to screw up. The only rule is “don’t eat” for 24 hours. As mentioned above, this is much easier than a 36 hour fast, especially for those new to it.
Secondly, like most methods of fasting, the abstinence from caloric intake for large periods of time is going to be a large part of the reason for success.
For example, if you generally eat 2,000 calories every day, that’s 14,000 calories over the course of a week.
If you remove two of those days, you’re eating 4,000 calories less. Without any other changes to your lifestyle, you’d be on pace for over a pound of fat per week. Even if you “compensate” and eat a little more on the days you’re not fasting, you are still going to wind up with a fairly substantial caloric deficit. Add in some exercise, and it’s not hard to see consistent weight loss.
Caloric manipulation aside, this style of fasting works incredibly well because of the effect that fasting has on your overall hormonal environment.
More specifically, when we talk about fasting, we’re really going to talk about two hormones: insulin and growth hormone.
With regard to insulin, it seems that the less often you eat, the less often you raise insulin levels. This is not surprising, obviously. It’s even less surprising that this would lead to fat loss, since we know that chronically elevated insulin levels make it very difficult to lose fat.
Therefore, if you’re eating less often, you’re going to have less insulin issues—even if you’re eating the same foods in the same amounts. (This, by way, is a pretty strong argument against the popular frequent feeding method of 5-6 meals per day). However, while fasting and infrequent feeding helps to control insulin and keep it low, that’s not enough to stimulate fat loss…unless growth hormone is present.
That is, if insulin AND growth hormone are both low, there isn’t a huge effect on fat loss. And so, while insulin management is important, growth hormone management is even more important.
Which brings us to the very predictable point: The effect of fasting on growth hormone is incredibly important.
Your body releases GH pretty consistently, but researched has shown increased secretion of growth hormone in three specific instances:
- During/immediately after sleep
- After exercise (as little as 10 minutes)
- During and immediately after a fast
Looking at these three things—all of which are thoroughly discussed in Pilon’s Eat-Stop-Eat—it’s not hard to come up with a “best of all worlds” scenario.
If you produce a lot of GH while sleeping, and you product it while fasting, then the obvious way to combine these is to continue fasting after you wake, allowing for prolonged GH secretion; from there, exercise will allow for increased production in addition to your prolonged secretion.
Overall, this maximizes both the presence of GH and its effect; and in addition, the elevated GH in combination with the low insulin is a deadly one-two punch to your body fat.
Finally one of the main benefits of both this style of fasting and the book itself is the incredible flexibility of the program and the ease with which you can adapt it to your lifestyle—you can fast any day you like, and can move it around at will to suit your social life, which is important.
DRAWBACKS: There aren’t many here. The main problem that clients of mine seem have here is that 24 hours seems like a long time to go without food; however, this is not unique to 24-hour fasting.
That said, there are some people who seem to have genuine problems with abstaining from food for significant length of time—in particular, people with low blood sugar seem to have an issue. If you fall into this category, you may want to tread lightly.
The only other real problem here would be for people who don’t want to miss out on post-workout nutrition but find the need to train on fast days. This can be alleviated by either moving your workout to the end of the fasting period, or simply scheduling your off days and fast days to coincide.
HOW (AND WHEN) I USE 24-HOUR FASTS: This is a style of fasting I tend to use when I get very busy and have to train in the evenings.
Also, I use this pretty much any day when I have to go out to a large social dinner and am not going to be watching my diet. For example, if I am going out on a Friday night, I might make my least meal Thursday at 8pm. Then, at dinner Friday, I’ll get to eat a lot of food, perhaps enjoy dessert, and be fine, even if I go out after and eat again.
OVERALL IMPRESSION: While this type of fasting is suitable for more than “damage control,” it works well for me in an occasional fashion. However, for many of my coaching clients, this is a sort of “every other day” approach that works well with them.
More than anything else, I frequently find myself referring people to Pilon’s book as a an IF primer, and a good resource for understanding a lot of the science behind why fasting work, and I’ll make that recommendation here: check out Brad’s site and book for more info.
SUMMARY: The Warrior Diet was the first type of structured fasting that I tried. I initially read about it in an interview with the author, Ori Hofmekler on T-Nation back in 1999. I tried the diet for the first time in 2002.
Simply, the diet is, in theory, a 20-hour fast followed by a 4-hour feeding period; as the name implies this is inspired by the nutritional habits of the warriors of antiquity, who certainly weren’t in the habit of eating six meals per day.
Instead, warriors in cultures ranging from Roman centurions to the Spartan elite subsisted on one to two meals: a large meal in the evening and (sometimes) a small meal in the morning; according to the author, that is.
The diet itself is modeled after this type of eating schedule; however, it’s worth noting that this is often criticized for not being “true” IF.
That is, in most cases, while having a small breakfast and a large dinner will probably work for weight loss, there may only be 8-10 hours between them…which, some people posit, isn’t long enough to get the benefits of fasting.
Moreover, during the fasting part of the day, the diet allows for mild consumption—you’d be allowed to eat a few servings of raw fruits and vegetables, and a few servings of protein (protein shakes included) if needed/wanted. These are kept quite small. Having said that, some fasting purists understandably maintain that Warrior Dieting, should you choose to exercise these options, is not fasting.
In practice, however, most people skip the small meal and simply have one large meal at the end of the day.
BENEFITS: Much like a 24-hour fast, a 20-hour fast allows you to reap the hormonal benefit of increased growth hormone. And, like all fasting, generally will result in fewer calories being consumed.
The benefit that is unique to this type of fasting is that you’re generally eating one large meal and, therefore, the make up of such a meal isn’t as important as you might think; as long as you get adequate protein, you can eat “junkier” foods and still do well.
Moreover, having only one meal makes life pretty simple, and less thinking means less screw-ups.
DRAWBACKS: On the flip side of that coin, once again we’re running into the issue of hunger; and again, this isn’t unique to Warrior Dieting.
The main drawback in my experience comes from the meal itself—trying to get all of your calories in a single meal means that meal is, by necessity, quite large; so large, in fact, that eating it often leads to discomfort. This is why many people turn to less wholesome foods: getting in 2000 calories of chicken, veggies and rice isn’t nearly as easy as getting it in chicken wings and French fries.
OVERALL IMPRESSION: A generally good dietary practice, and certainly easy to follow.
One criticism often made is that the points are made via story and anecdote, with very little in the way of scientific evidence to support the arguments. While some IF authorities dismiss the Warrior Diet based on that, I feel it should be respectfully acknowledged, given that it was the book that got people talking several years back.
Moreover, while the book does lack in science, it’s truly an enjoyable read. The author has a very engaging writing style and adding to the fun is the fact that he was an editor for Penthouse.
Plus, if that wasn’t cool enough, as mentioned earlier, this diet is based on the eating habits of awesome warriors–including Aragorn, son of Arathorn, Heir to the Throne of Gondor, of the Lord of the Rings fame.
Seriously, check it out. In this video, Aragorn debates the merits of Warrior Dieting vs. Frequent Feeding with Pippin:
SUMMARY: Popularized by Martin Berkhan, Leangains or 16/8 intermittent fasting is a daily fasting method that requires abstaining from food for 16 hours, with the remaining 8 hours comprising the feeding window. During this time, users may eat as many (or few) meals as desired, with the most frequent iteration being three meals.
Designed specifically with training in mind, the 16/8 method has specific post-workout suggestions and recommendations; as such, 16/8 is the most popular form of intermittent fasting among those who train for aesthetics and physique enhancement.
Berkhan is great in terms of showing his research, his clients get excellent results, and is one of the few people aside from myself who liked Final Fantasy 6 better than the inferior but infinitely more popular FF7.
BENEFITS: In addition to having all of the benefits inherent in other types of intermittent fasting, the 16/8 method is a stand out as it allows for an advanced level of hormonal management.
While something like 24-Hour fasting or Alternate Day Fasting will give you these benefits, these methods are not for daily practice, whereas 16/8 is. This means that you are going to have a daily increase in GH, potentially increasing the effects.
Moreover, daily practice (obviously) usually equates to a consistent feeding schedule, which is better for hunger management. Put another way, some people experience difficulty with fasting for 24-36 hours because they do it infrequently; not an issue with daily practice.
Finally, condensing all food intake to an 8-hour window leads to greater satiety, as a number of studies have borne out that larger, infrequent meals are superior to small, frequent meals.
DRAWBACKS: There are very few drawbacks to this style of IF, and these mainly come from scheduling. You see, from everything I’ve seen and read, the LG protocol is MOST effective if the workout is performed in a fasted state, and the meal that breaks the fast is immediately post-workout.
For some, execution can become a little impractical; for most people, adhering to that simple rule forces them to shift the feeding window to inconvenient times.
I find that most of my clients are able to workout either in the morning (roughly 6am, before work) or in the evening (6pm), after work.
Given that we want to have a 16-hour fasting window that ends with the PWO meal and begins an 8-hour feeding window, you can see how either of those times present some issues. For example, let’s look at 6am. In order for this to work as your first meal, your last meal is going to be at 4pm (allowing you to fast for 16 hours for your next feeding window).
I addressed scheduling issues in this article covering many of the frequently asked questions about intermittent fasting, but it’s worth touching pointing out some potential problems with this set up:
That said, if you’re looking to try 16/8 and can only work out in the AM, it’s certainly doable, just be aware of this going in. And, of course, this “problem” is really only applicable to certain people.
Like any other style of eating, make it work for you—within the rules of the system.
HOW (AND WHEN) I USE 16/8: This style of fasting fits very well with my life as I work from home.
For me, it’s very easy to plan my meals and workouts around one another, and making last minute changes isn’t a problem.
Most days of the week—usually Wednesday through Saturday—I do some form of 16/8. I like to workout anywhere between 12 and 2pm, so I just judge my last meal the night before based on when I’m going to train the next day. Sometimes I’ll wind up with an 18 hour fast instead of 16, but, again, this is really no big deal.
OVERALL IMPRESSION: Of all intermittent fasting protocols, 16/8 is probably the most sophisticated, in terms of both intention and execution. While most fasting is effective mainly because it prevents you from eating, the Lean Gains style is really about making your hormones your bitch. Which is awesome.
This style of IF is best for serious folks and those who are already lean; and, again, this is the only style of IF that was designed specifically with fitness-oriented people in mind, and therefore yields exceptional results for folks who train consistently.
Fasting is just not eating. But there are ways to not eat strategically. This overview of the most popular types of Intermittent Fasting (as well as the benefits and drawbacks of each) should provide enough insight to guide you towards the method that’s right for you. If you’re looking to try an IF plan, simply choose from those above, and read up on them.
While all of them are effective, the most important thing is to choose the one that fits in best with your lifestyle, and give yourself the greatest advantage.
One final point: specifically because intermittent fasting is not a diet, it lends itself well to nearly anything that is a diet. You can practice intermittent fasting regardless of your nutritional restrictions or preferences—it doesn’t matter if you’re low carb, Keto, Paleo, vegan, or anything in between.
Intermittent fasting is 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.