Is Intermittent Fasting Good For Bulking?

Have you ever wondered if intermittent fasting was good for bulking? After all, it helps you produce more growth hormone, which could help with muscle growth; it increases increase in insulin sensitivity, which could help make your gains leaner; and research shows that it helps preserve muscle when losing weight. This could theoretically make intermittent fasting a good bulking diet… right?

On the other hand, most bodybuilders bulked up by doing the exact opposite of intermittent fasting. The guys with the most famous physiques in history all ate at least a few meals per day. Why?

Furthermore, we hardgainers and ectomorphs are notorious for having tiny stomachs, raging metabolisms and small appetites—all of which make bulking up way harder. Will intermittent fasting work for our naturally skinny body type?

There are good arguments to be made for and against intermittent fasting. In this article we’ll go over the muscle-building advantages and disadvantages of intermittent fasting, then take a look at some studies that compared it against a traditional bulking diet. By the end, you’ll be able to decide if it’s a good approach for you while bulking.

The Benefits of Intermittent Fasting While Bulking

First of all, intermittent fasting is indeed a totally science-based diet, and the benefits have been proven quite conclusively. For example, here are four high-quality studies showing an increase in growth hormone in men while intermittent fasting: study, study, study, study.

It’s now mainstream scientific knowledge that intermittent fasting has several proven benefits that can improve your health and body composition:

  • Reduction in appetite leading to a comfortable decrease in total calorie intake.
  • An increased production of human growth hormone.
  • Improved insulin sensitivity.
  • Less risk of muscle loss compared to a standard diet.
  • Greater cell repair (autophagy).

These claims aren’t being disputed whatsoever in the scientific community. Here’s Examine.com giving a mainstream definition and summary of the research on intermittent fasting:

Our bodies are well equipped for long periods of time without food. Generally, a bout of feeding and digestion is followed by an episode of digestive quiescence (i.e., fasting). In modern days, feeding is rather frequent and fasting tends to be limited to our sleep, plus one or two hours on either end. In other words, no more than 8–12 hours for most people. Intermittent fasting (IF) simply extends this fasting period.

Fasting can be defined as voluntarily abstaining from food (or from certain types of foods) for a given period of time. IF can take many forms, such as alternate-day fasting (ADF), 5/2 dieting (eating at most 500 kcal on two non- consecutive days each week), and time-restricted feeding (TRF; eating only within a set daily time window, which usually lasts 8–12 hours). Ramadan fasting (the Muslim holy month, during which food and drink are consumed only when the sun has set) is a religious form of TRF.

Compared to eating normally, TRF reduces fat mass without affecting fat-free mass or strength from a concurrent resistance training program. Compared to daily caloric restriction, ADF produces greater reductions in fat mass and smaller reductions in fat-free mass. In addition to its proven efficiency, IF has the advantage of only restricting when you eat, not necessarily how, meaning that it can be integrated with other dietary approaches that you enjoy.

However, as you can see, most of these benefits are being researched for how they affect fat loss, not muscle gain. What we’re interested in is how intermittent fasting affects bulking—weight gain.

Because we’re only interested in bulking, we can immediately discount the main advantage of intermittent fasting: appetite reduction. After all, we aren’t trying to eat less food. Quite the opposite, actually. This is a bulking disadvantage, especially for naturally skinny guys, as most of us already struggle to eat enough to gain weight.

But let’s ignore that disadvantage for a moment. Just for the sake of argument, let’s say that even while intermittent fasting, you’re able to eat enough calories to gain weight. If you can eat enough calories, then you can make leaner gains, right?

Leaner gains from intermittent fasting: truth or myth?

Intermittent fasting is an extreme example of calorie cycling. To understand how intermittent fasting affects our gains, first we need to understand how regular calorie cycling affects our gains.

Calorie cycling while bulking. The first thing we need to do is make a distinction between bulking and cutting. You can use calorie cycling to help with either goal, but the effects are rather different. When you’re bulking, you’re in a calorie surplus, and your body is totally primed for muscle growth, allowing you to build muscle quite rapidly. Dr Mike Israetel summarizes the benefits of a calorie surplus as follows:

  • More testosterone and insulin
  • Enhanced cellular signalling
  • Massive nutrient influx

So while we’re bulking, we have quite a bit of potential to build muscle. Let’s imagine it with a simplified graph like this, where the empty area under the dotted line is how much muscle your body is capable of building over time if you do everything perfectly:

As you can see, it’s not a flat line. Your body will be primed for muscle growth after a good workout, and then that muscle growth will gradually slow down as time passes, usually grinding to a halt within 72 hours.

The other thing to keep in mind is that any calories which cannot be invested into muscle growth will be stored as fat. This means that if you eat a large calorie surplus (blue line), you’re going to gain a maximal amount of muscle (red) but you’re also going to gain quite a lot of fat (yellow). This called a “dreamer bulk,” and it looks like this:

Most people don’t want to gain that much fat, so they do what’s called a “lean bulk,” where they eat a smaller calorie surplus, like so:

By bringing down your calorie intake, you’re still gaining almost as much muscle, and you’ve cut out most of your fat gain. However, this is a compromise. You’re not eating enough calories to fully maximize muscle growth after your workouts, and you’re also gaining some extra fat because you’re not tapering off your calorie intake as your muscle growth potential slows.

You can improve your gains by lining up your calorie intake with your muscle growth potential, eating extra calories in the couple meals following a workout, and then easing back on the calorie surplus afterwards. This is still a “lean bulk,” but now with the help of calorie cycling, we’re getting a little more muscle growth:

The first thing to note here is that even though you’re calorie cycling, you’re still always in a calorie surplus. The degree of the surplus varies, but that blue line representing your calorie intake is still always above the baseline (the black line at the bottom). There’s a constant influx of nutrients, your body is always pumping out tons of testosterone, and you’re always benefitting from enhanced cellular signalling. This ensures that you’re building muscle all day long, taking full advantage of your growth potential. (This is how we structure the diet in our Bony to Beastly Program.)

The next thing to note is that even though your calorie intake follows the curve of your muscle-building potential, there’s still that thin yellow strip of fat gain. You could try to get rid of that yellow strip by reducing your overall calorie intake… but you probably shouldn’t. In order to get all of the muscle-building advantages that come along with a calorie surplus, it actually helps to have a little bit of padding there. Bulking isn’t about eating enough calories, bulking is about eating extra calories.

Now, this doesn’t mean that you should be getting noticeably fatter as you bulk. If you start bulking at 15% body fat, then so long as you’re gaining 85% muscle and 15% fat, your body fat percentage is going to remain at 15% as you continue gaining weight. Furthermore, because your muscles are growing so much bigger, you’re actually going to look leaner as grow.

That would be the ideal situation, anyway. Realistically, you’re probably going to gain a few body fat percentage points. Maybe you anticipate this, so you start your bulk at 11% and then stop bulking when you notice that your body fat percentage has climbed to around 15%. That’s perfectly fine, and in the mirror, this should have you finishing with about the same muscle definition as when you started, like Jared did here, gaining 33 pounds in 90 days:

Calorie cycling and intermittent fasting. Intermittent fasting doubles down on calorie cycling. During the feeding windows, you have more than enough calories to build muscle at full speed, and during fasting periods, you’ll actually dip into a calorie deficit, losing fat. This creates the misconception that you can lose fat even while you’re bulking up.

The misconception comes from the fact that in order to gain weight you need to be in an overall calorie surplus, and that means that during your feeding periods, you need to make up for all the calories you missed while fasting. This means eating so many damn calories that there’s no way to invest all of them into muscle growth, causing the extra calories to spill over into fat storage. So what happens is that you lose a bit of fat while fasting, then gain a bunch of fat during the feeding window, like so:

How to make lean gains with intermittent fasting: If you’re bulking very slowly, gaining just a pound or two each month, then your calorie surplus doesn’t need to be very high. In this case, with such a small overall surplus, you miss out on the extra testosterone, nutrients, and cellular signalling, so your growth potential slows down, like so:

You won’t be able to build muscle as quickly, but in some situations this might still be the better approach. For example, if you’re a fitness model trying to maintain yearlong leanness, and you’re happy making very slow gains, you might prefer this method. Guys like Martin Berkhan (LeanGains) and Gregory O’Gallagher (Kinobody) do a good job of this. They might be able to get results that look something like this:

However, to say that their programs are designed for this would be to sell them short. Even the LeanGains intermittent fasting protocol is designed for fat loss and muscle maintenance, not for bulking. To quote the guy who created it, Martin Berkhan:

The “gain” in Leangains can therefore be a bit misleading, as most of my clients wants to lose fat, while retaining as much muscle as possible in the process.

Intermittent fasting absolutely shreds in a deficit. I don’t want to make it seem like I’m thrashing intermittent fasting. The evidence is quite clear that intermittent fasting is fantastic when you’re trying to lose weight. It allows you to dig into a massive calorie deficit for most of the day, and then you can pop up for a bit of muscle growth in that prime post-workout window, like so:

Yes, the amount of muscle you build will be unbelievably small compared to when you’re bulking, but with traditional cutting, you wouldn’t really be building any muscle at all:

Again, I should point out the exceptions. Total beginners, obese people, and guys on steroids can build muscle and lose fat at the same time more easily, so they can expect better results than are shown in these graphs. This applies to all of the graphs equally, whether or not they are calorie cycling or intermittent fasting. On that note…

Calorie cycling won’t have a big impact on your results. Calorie cycling pales in comparison to the quality of your workouts, the quality of your diet, your overall calorie intake, your overall protein intake, and how well you’re sleeping. Because the effects of calorie cycling are so minor, I would consider it a bonus technique, not a foundational technique. However, it does work, and because it’s so easy to add into your routine, we recommend it to almost everybody—including all of our members, both when cutting and bulking.

So does intermittent fasting allow you to make leaner gains while bulking? No. If you’re trying to build muscle quickly, you’ll likely make leaner gains with regular calorie cycling instead of intermittent fasting. However, it won’t impact your gains that much either way, so you should also factor in your personal preferences.

Okay, now that we’ve seen what intermittent fasting can and cannot do, let’s see what frequent eating has to offer.

The Benefits of Eating More Frequently While Bulking

There used to be rumours about “stoking the metabolic fire,” where in order to maintain a healthy metabolism, people thought they had to eat every three hours. That was disproven, and it was more of a fat-loss concern anyway.

When it came to bulking, bodybuilders worried that if they spent a prolonged period of time fasting, then their bodies would begin to eat away at their muscle mass (catabolism). That was also disproven. Intermittent fasting is fantastic for maintaining muscle mass, even in an overall calorie deficit.

However, research has turned up some genuine advantages to eating frequently:

  • If you eat twice as often, your meals can be half the size. This allows guys with small stomachs to comfortably eat enough food while bulking, and it prevents the feelings of lethargy after large meals. One good way to take this principle even further is by having snacks between meals.
  • More testosterone. Being in a calorie surplus allows you to build more muscle by improving testosterone production, cellular signalling and providing a constant influx of nutrients. The more time you spend in this muscle-building surplus, the more muscle you will build over the course of the day.
  • Less cortisol? A recent study looking at 16:8 (LeanGains) intermittent fasting found that the group who skipped breakfast not only produced less testosterone, but also more cortisol—even while eating a comparable amount of calories overall. This would lead to less muscle growth and more fat gain. However, some of these hormonal changes, while not good for building muscle, might be good for improving your longterm health. So it would seem that intermittent fasting would perhaps be better for day-to-day muscle maintenance, but worse in terms of trying to build muscle leanly.
  • More muscle-protein synthesis. Researchers have proven that every time you eat a meal that’s rich in protein, you trigger muscle growth (aka muscle-protein synthesis). This means that the more often you eat (up to a maximum of 5 meals per day), the more muscle growth you can stimulate.

Let’s dive deeper on that fourth point. If we’re intermittent fasting, are we sabotaging our gains by missing out on opportunities to trigger bonus muscle growth?

Dr Layne Norton’s research is the most relevant here (study, study, study). We’ve already shown how lifting weights triggers a period of muscle growth that lasts for up to 72 hours, but to take advantage of that opportunity, you also need to be on point with your diet. Norton found that when we eat a meal with enough protein in it, it triggers a surge of muscle growth that gradually slows down over the course of around six hours, like so:

This isn’t just “potential” muscle growth, this is your body actually constructing muscle. That means that if you eat three meals per day, you’d be having muscle growth spurts that look something like this:

Already we can see that skipping a meal is a missed opportunity for muscle growth:

This Nortonian model of muscle growth brings up some questions. First of all, if you miss a growth opportunity, can you make up for it later by eating a meal that has extra protein in it? For example, what if we could do something like this:

Unfortunately, catching up is not possible. Norton’s research has proven that muscle growth is maximally stimulated with around 40 grams of protein. If you have more than 40 grams of protein in a meal, no additional muscle growth is triggered. So if you skip a meal, or eat a meal with too little protein in it, there’s no way to make up for it by eating more protein in the next meal. This means that it’s better to spread your protein intake out over the course of the day.

Note: it’s fine to eat more than 40 grams of protein per meal. If you have more than 40 grams in a meal, that’s perfectly fine, and that might be needed in order to hit your daily macro goals, but it won’t trigger extra muscle-protein synthesis.

Note: 20 grams of protein still stimulates a lot of muscle growth. While eating 40 grams of protein per meal will get you the absolute ideal amount of muscle growth (100%), eating just 20 grams of protein will get you most of the results (80%). If you don’t hit 40 grams of protein in every meal, that’s fine, just make sure to get at least 20 grams.

For example, it’s common to have more protein with dinner than with breakfast, so a common way to distribute your protein over the course of the day might look something like this:

The breakfast will still produce good muscle growth, and that large amount of protein with dinner will still be fully digested. It’s not perfectly ideal, but it’s pretty good. If you wanted to 100% maximize your muscle growth, though, you’d move 20 grams of protein from dinner to breakfast, giving you at least 40 grams in each meal.

This raises another question. How often can we stimulate muscle protein synthesis? Could we eat protein all day long, perpetually maintaining peak muscle growth conditions? What about something like this?

Layne Norton tested this idea and discovered that we can only trigger muscle growth once every four hours or so. If we eat meals more frequently than that, again, the protein will contribute towards our daily macros, but the meals won’t stimulate extra growth via muscle-protein synthesis.

This leaves us with an ideal meal schedule that looks something like this:

How controversial is this research? Could it be wrong? While there are still some questions about this theory, most of them are finer details, not issues with what we’ve discussed above. One of those finer details is that these spurts of muscle growth seem linked to one specific component of protein (leucine), not our overall protein intake. Dr Stuart McGill’s research has shown that some protein sources have more leucine than others, so it’s not quite as simple as just making sure to eat 40 grams of protein (study). For example, you can get maximal muscle growth with just 27 grams of whey protein, whereas you might need more like 50 grams of rice protein in order to get the same effect.

However, Norton’s overall research isn’t controversial. In fact, it’s the dominant theory among the top researchers in the field, including both Dr Eric Helms and Dr Brad Schoenfeld. To quote Schoenfeld:

The anabolic effects of a meal last a maximum of 6 hours or so. Thus, consumption of at least 3 meals spaced out every 5 to 6 hours would seem to be optimal for keeping protein synthesis continually elevated and thus maximizing muscle protein accretion. This hypothesis needs further investigation in a controlled long-term study.

Now, one discrepancy to note is that Norton recommends eating every four hours, whereas Schoenfeld recommends eating every 5–6 hours. While their recommendations are slightly different, their understanding of the research is not. Norton is simply erring on the side of eating more often, whereas Schoenfeld is erring on the side of eating a little bit less often. They’re both giving advice based on the same understanding of the science.

How do calorie cycling and protein distribution fit together? We’re talking about the same phenomenon in both cases: an increase in muscle-protein synthesis. After a good workout, muscle-protein synthesis will shoot up and then slowly decrease over the course of a few days. Eating a meal that’s rich in protein has a similar but shorter effect, lasting just a few hours.

If you consider that you’re going to have extra growth potential immediately after training, does that mean you should be eating extra protein post-workout? Yes. Some recent research is showing that after a hearty full-body workout, there’s a benefit to having some extra protein.

So you might consider your ideal workout day to look something like this:

This is a pretty classic bodybuilding diet, where you eat 4–5 meals per day and have an especially big post-workout meal. Fairly simple, and fairly ideal.

Does this mean you should be eating 4–5 meals per day? Yes, but keep in mind that they don’t all need to be massive meals. You can trigger muscle growth just as easily with snacks, such as a bit of greek yogurt, a protein bar, a protein shake, or some cottage cheese. These snacks should actually make your overall diet easier, as they will allow you to have a smaller breakfast, lunch and dinner.

However, don’t worry if you can only eat three meals per day. Just have breakfast early, have dinner late, and make sure that all of your meals have at least 20 grams of protein in them. It won’t be perfectly optimal, but that way you’ll spend most of the day with boosted muscle growth.

But what about growth hormone? The main muscle-building advantage of intermittent fasting is often said to be growth hormone, and if we’re eating steadily throughout the day, we’re missing out on having elevated growth hormone during our fasted periods. So, should we eat more often to get more muscle-protein synthesis, or fast to get more growth hormone?

Let’s compare the two overall approaches.

Intermittent Fasting vs Traditional Bulking

We’ve looked at the muscle-building advantages of intermittent fasting, with the main advantage being that you’d produce more human growth hormone. We’ve also looked at the muscle-building advantages of eating more frequently, with the main advantage being that you’d stimulate more muscle growth more often.

Which advantage is greater? Researchers have compared different meal schedules and concluded that having several meals spread out over the course of the day builds more muscle than intermittent fasting (study).

Eating 3–6 meals per day is ideal for muscle growth, especially if you’re skinny.

Eating more frequently will result in leaner gains. Since the amount of calories you eat determines the amount of weight you gain, and since intermittent fasting reduces muscle gain, this means that while the overall amount of weight you gain in either situation will be the same, you’ll gain less muscle and more fat with intermittent fasting.

Eating more frequently makes it easier to eat more calories. And keep in mind that if you have a smaller stomach, eating more frequently is absolutely essential while bulking. Your stomach simply won’t be able to handle the massive meals of an intermittent fasting bulking protocol. (We’ve had members attempt this and wind up giving themselves acid reflux.)

The best types of intermittent fasting for bulking

By now it should be clear that we don’t consider intermittent fasting to be ideal for bulking. However, nutrient timing isn’t that big of a factor when it comes to muscle growth. If your workouts, diet, protein intake and sleep habits are all good, you can make good gains with anywhere from 2–7 meals per day.

This means that intermittent fasting is still a valid option, even while bulking. Furthermore, some intermittent fasting diets take some of our criticisms into consideration.

Using BCAAs to stimulate muscle protein synthesis. The main disadvantage of fasting while bulking is the lack of muscle protein synthesis. However, what if it were possible to stimulate muscle protein synthesis while fasting? This would allow you to get the best of both worlds, right?

Supplementing with leucine or branched-chain amino acids (BCAAs) sort of allows you to do that. They contain enough of the amino acid leucine to trigger muscle-protein synthesis, but they contain so few calories that Martin Berkhan still considers it fasting. The downside is that since you’d still be in a calorie deficit, there wouldn’t really be any muscle growth going on. (The strategy works better while cutting, as the BCAAs prevent muscle loss and improve workout performance.)

Fasting just once per week? There are also types of intermittent fasting where you only fast for one 24-hour period each week. The most famous version of that is Brad Pilon’s Eat, Stop, Eat approach, and that’s also the approach Dr John Berardi used when testing out an extreme bulking plan on the fitness blogger Nate Green (Bigger, Smaller Bigger).

There are three benefits to doing 24-hour fasts. The first is that they give your digestive system a total break from the stresses of overeating; the second is that you get to burn a little bit of fat right in the middle of your bulk; the third is that if you’re only fasting for one day each week, then you’d be growing at full speed 86% of the time. That’s a big improvement compared to 16:8 fasting, where you’d only be growing at full speed for around 67% of the time.

There are also two downsides to 24-hour fasts, though. First, you won’t be building muscle on the day that you’re fasting, and this will slow your results down. Second, it can be extremely unpleasant for some people.

If you want to experiment with 24-hour fasts, I recommend scheduling them as far after your workouts as possible, where there wouldn’t be much muscle growth taking place anyway. For example, your week could look like this:

Monday: full-body workout
Tuesday: rest
Wednesday: full-body workout
Thursday: rest
Friday: fully-body workout
Saturday: rest
Sunday: fast

So. daily 16-hour fasts or weekly 24-hour fasts? From a results perspective, I think 24-hour fasts are a more logical approach. Your digestive system will enjoy the break, you can schedule it far away from your workouts, you might actually lose a decent amount of fat, and it won’t slow your results by very much.

However, from a lifestyle perspective, most people—especially guys in their 20’s—seem to prefer 16-hour fasts. They quickly get used to skipping breakfast, and they often find that it helps them be more productive in the morning. The 24-hour fasts, on the other hand, can be quite unpleasant, even for young guys who are good at following intense diet protocols.

The Skinny Guy’s Bulking “Fast”

Okay, so we can see that there are two significant advantages to intermittent fasting while bulking, namely:

  • Our digestive system gets a break from overfeeding. Bulking diets can be brutal on skinny guys. There are just so many damn calories that it can feel like a relentless assault on our stomachs and energy levels. Taking a day off each week where we don’t eat any calories can be a welcome break.  
  • Skipping breakfast is pleasant and productive. Most skinny guys wake up without much of an appetite, making breakfast more of a chore than a treat. Moreover, eating a big breakfast can use up our morning energy on digestion, especially if we have weaker digestive systems (and many of us do).

However, there are also two major downsides to intermittent fasting:

  • Less muscle growth, more fat. When you’re fasting, your muscles aren’t growing. This will not only slow down your muscle gains, you’ll also gain more fat.
  • Intermittent fasting makes eating enough to gain weight way harder. It’s hard enough to eat a bulking diet when you’re eating 3–5 times per day. Cram those calories into a couple meals over the course of a few hours and it becomes downright brutal. Who wants to eat a 1,500-calorie lunch? Lots of people, sure, but I’d rather stick a fork in my eye.

So, how can we min-max our results based on all of this research? I have two protocols that you might want to experiment with. Keep in mind that you’re always free to follow a traditional bulking diet, eating 3–5 regular meals per day. But if you find yourself wanting to experiment with intermittent fasting, here’s what I would recommend instead:

The Mini-Meal Reverse Cheat Day: 24-hour fasts allow your digestive system to take a break, and it might give you a chance to lose a little bit of fat right in the middle of your bulk. That’s great, but we can accomplish all of that without any fasting whatsoever.

Instead of fasting once per week, we recommend having a “cheat day.” But instead of doing the fat-person cheat day, where you eat extra food, we recommend doing the skinny guy’s cheat day, where you eat less food. You can still eat several times per day, just keep your protein intake high and your calorie intake low. Your digestive system will love the break, and you’ll lose some fat. (This is how Jared gained 33 pounds in three months, as shown above.)

This would look like this:

Monday: full-body workout, eat big
Tuesday: rest, eat big
Wednesday: full-body workout, eat big
Thursday: rest, eat big
Friday: fully-body workout, eat big
Saturday: rest, eat big
Sunday: take a break from eating big

The Light Breakfast: Skipping breakfast increases morning productivity, but you miss out on an opportunity to stimulate muscle growth. The solution is to have a protein-rich breakfast that’s smaller and lower in calories. This could be a protein shake and some fruit, a protein bar and a latte, or even just a smoothie. All of those will be quite easy to digest, they aren’t very filling, and they can contain at least 20 grams of protein. The meal will be light enough that you’ll still be productive, you won’t fall too far behind on calories, and you’ll kick-start some morning muscle growth.

These half-fasts are what Dr Layne Norton recommends to bulkers who are curious about intermittent fasting:

If you want some of the benefits from intermittent fasting but want to optimize muscle mass, I would advise a different type of fast. Rather than cutting out all calories, simply restrict carbs and fats during your fasting window, but continue to evenly distribute your protein intake throughout the day.

Take this approach, and you are still going to get a large volume of food in the feeding period and spend a large portion of the day in a low-insulin fat-burning state, but you’ll be able to distribute protein in such a way that is better for muscle growth.

This is what we recommend to our members, and this is how I managed to gain 55 pounds over the course of a couple years:

Summary: Is Intermittent Fasting Good for Bulking?

Most of the bad rumours about intermittent fasting are false. You won’t lose muscle while fasting, it won’t tank your metabolism, and your body won’t have any trouble digesting 80+ grams of protein per meal.

Moreover, many of the benefits of intermittent fasting are true. For example, intermittent fasting really will allow you to naturally produce more growth hormone, and it really does help people maintain more muscle mass while cutting.

However, intermittent fasting is still bad for bulking. Intermittent fasting is designed to help overweight people lose weight and still feel satisfied by eating large meals. It also helps people burn fat while retaining the muscle they’ve already built. But intermittent fasting is not helpful for skinny guys trying to bulk up because it makes it harder to eat enough calories, it limits muscle growth during the fasting period, and the main advantages don’t help with muscle growth anyway. As a result, intermittent fasting is not a great approach for people who are trying to prioritize muscle gain.

Just to further emphasize how consistent researchers are with their opinions on intermittent fasting, here are the researchers over at Examine.com weighing in with their bulking advice:

Meal frequency is a topic of much debate. For decades, “six meals per day” has been a bodybuilding mantra, but now the intermittent-fasting crowd claims we can be awake for hours, even a whole day, without eating a bite — and be healthier for it!

The truth probably lies somewhere in the middle.

Skeletal muscle protein synthesis changes with amino acid concentrations in the blood; our bodies become desensitized to the anabolic stimulus of protein after about three hours. Eating too frequently can therefore impede muscle protein synthesis.

On the other hand, you don’t want to deprive your muscles of the amino acids they need to grow. Since a moderate-sized meal might take up to 5 hours to be digested, it seems prudent to eat something every 4–6 hours, which translates to 3–4 meals per day.

References: study, study

So there we have it. Intermittent fasting is great for cutting, but if you want to build muscle as quickly and leanly as possible, it’s better to eat 3–5 meals per day.

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13 Comments

  1. SoSkinny on July 10, 2018 at 10:39 am

    Bulking takes consistent work and financing. Almost every guy falls because it’s too hard to get all of that support and stay motivated long-term. The body reverts back to its original shape and form within 2-months of stopping the bulking focused work. Don’t waste time.

    • Shane Duquette on July 10, 2018 at 11:09 am

      Hey man, bulking is indeed hard work. Many guys do fail, and that’s why those who succeed are rewarded so highly for it: they prove to themselves and everyone else who sees them that they can accomplish difficult tasks. When you see a guy in great physical shape, you know that he can work hard, that he can handle his finances, that he can stick with his goals long-term, and that he has the support he needs to succeed in life.

      The body doesn’t revert back to its original shape and form, though. The more important adaptations that your body makes from building muscle are permanent. For example, your muscle fibres bring in myonuclei from satellite cells, making your muscles more insulin sensitive and your body able to support greater muscle mass. This is colloquially called “muscle memory,” and it will last your entire life, making you forever leaner and more muscular. We’ve written more about that here:
      https://bonytobeastly.com/skinny-changing-set-point/

      (We still recommend keeping up with a healthy diet and exercise routine, though, of course, but that’s important whether you build muscle or not.)

      • SoSkinny on July 13, 2018 at 8:13 pm

        Inspiring that you found YOUR confidence and some passion through doing this, Shane. Many do not. Many cerebral guys have no interest in dead-lifting 300 or 400lbs and becoming more of a meat-head. However, bodies do revert or become ‘fattier’ in lieu of the muscle that once was perhaps more pronounced when the program or routine ceases…consider it an appropriate reaction and homeostasis to the *inflammation* that the work causes when the routines can’t be upheld. In addition, age is a factor! Testosterone declines every year after 30. I don’t know which world you live in, but most physically-fit men I know become too into themselves, cheat on partners, shark their way in corporate and cut pushed back down, or even end up in the sex industry as masseurs and escorts, etc. That is not ‘financial support’. That is desperate hustling to keep the vicious cycle going that only proceeds in a negative feedback loop. Why? Because we’re human, not machines, and our lives are finite that slow in pace over time.

        *fall* verses *fail* in original post. People fall from grace. Becoming a surly, obsessed, angry health-nut or exercise fiend is a fall from grace and intellectual cultivation. Mild exercise is ok, especially for ‘Depression’ which academics suffer from frequently. High intensity like HIIT or Cross-Fit often yield injuries.

        • Shane Duquette on July 14, 2018 at 9:37 pm

          All of the research I’ve seen has shown a positive correlation between lifting weights, confidence, intelligence, and emotional well-being. Many benefits come from doing cardio as well, but both lifting and cardio give separate benefits, so doing both is even better than doing one or the other.

          I can’t imagine why being stronger, healthier, and successfully accomplishing a difficult task would make someone less confident or less happy, but I’m sure it happens to some people. I’ve never encountered one of those people. I suspect they’re rather rare.

          Building muscle has a positive effect on brainpower, so being a meathead is a bit of a misnomer. Yes, there are dumb people who lift weights, but they’re smarter than they would have been if they didn’t lift weights. It’s helping, not hurting. (Again, similar but different effects from cardio. Best to do both.)

          You don’t have to deadlift 300–400 pounds in order to build muscle or be healthy. You’re strawmanning me here. I’m personally glad that I was able to accomplish my goal of lifting 405 pounds, but I have no doubt that when I was lifting 315 I was just as healthy. (My bone density reached the optimal level before I deadlifted 405 pounds.)

          Muscle does not in any way transform into fat. If anything, having formerly been muscular makes one more resistant to gaining fat, and more likely to gain muscle when overeating. The formerly strong guy who becomes fat will have a better physique than the formerly sedentary guy who becomes fat.

          As for cheating… don’t cheat? Not sure what that has to do with going to the gym. Yes, guys with naturally high testosterone may be more likely to cheat, but again, that has nothing to do with going to the gym or building muscle.

          Anyway, none of this has anything to do with intermittent fasting while bulking.

  2. Vincent on July 10, 2018 at 4:37 pm

    Very interesting article! But I have one question:
    – What is the importance of hitting your daily protein goal?
    Let’s say you are a 160lb guy and you skip some meals but you get all you protein in later that day in huge portions (e.g. 2 meals with 80g of protein) and hit your daily protein goal.
    What’s the benefit of that over eating 2 meals with 40g of protein that evening and only hitting half of your daily protein goal?
    Because you can’t catch up and won’t stimulate more muscle protein synthesis with those 80g protein meals if I understand correctly?

    Thanks in advance!

    • Shane Duquette on July 10, 2018 at 5:36 pm

      That’s a good question, your logic seems sound to me, and I’ve wondered the same thing myself. Let me walk you through what I know and what I think, but this is something I’ve been looking into as well. So, while I feel confident in the “what” and “how,” I feel like I’m missing part of the “why.”

      1. Studies find that those who eat less than 0.8 grams of protein per pound bodyweight per day don’t build as much muscle as those who eat more, regardless of when they eat it. So we know that this is important. In fact, it’s more important than when you eat the protein.

      2. Studies also find that the best way to distribute that protein is relatively spread out, with at least 20 grams in each meal, rather than having it all at once. This is newer research and seems to have less of an impact, which is why people can gain muscle even while following extreme intermittent fasting protocols, such as the warrior diet, where you have just one giant meal each day.

      3. Furthermore, the research shows that no matter how much protein we eat in a meal, our body is still able to digest and use all of it. This means that if you have 180 grams of protein with dinner, and that’s the only thing you eat all day, your body is still going to get the benefit of eating 180 grams of protein.

      However, if you’re hitting your daily protein goal but you aren’t spreading out that intake throughout the day, you wouldn’t get the EXTRA benefit of stimulating these boosts in muscle-protein synthesis.

      Perhaps we can look at our calorie intake the same way. Let’s say you need to eat 3,200 calories per day in order to gain a pound per week. Option A is to eat four 800-calorie meals, keeping you in a hearty surplus all day, with your testosterone high and your cortisol low. Option B is to eat one 3,200-calorie meal, meaning that most of the day you’re in a calorie deficit, your testosterone is low, your cortisol is high, and you don’t have an influx of nutrients. In both cases, you’ll absorb all of those calories, and therefore in both cases you’ll gain weight. Your total calorie intake is priority #1. However, if you spread those calories out throughout the day, your gains will be leaner, as your body can constantly build muscle all day long.

      I suspect something similar is happening with protein.

      Does that help at all?

  3. RR on July 10, 2018 at 5:58 pm

    Very thorough article as always. Makes sense mostly. However there are a couple of key points to highlight.

    1. IF really works only with a high (good) fat diet with moderate protein and low carbs. This helps comfortable fasting for 16+ hours where the body switches from glucose to fat for energy and all the fat loss happens. So the following paragraph declaring that IF causes fat gain by assuming one eats the same amount and type of calories is a gross mischaracterization:
    “Since the amount of calories you eat determines the amount of weight you gain, and since intermittent fasting reduces muscle gain, this means that while the overall amount of weight you gain in either situation will be the same, you’ll gain less muscle and more fat with intermittent fasting.”
    As a side note, such a (keto-like) diet is good for anyone even if not fasting and helps hit the right macro ratios.

    2. There are other benefits of fasting you’ve missed like immunity system boost, improved liver functioning, better sleep etc all of which help in long term muscle gain and fat loss.

    3. The bit on fasting increasing cortisol is a red herring. I found this on a good IF website that addresses this thoroughly:
    “Exercise also raises cortisol, so should we not exercise? Dieting will lead to more cortisol, as will low carbohydrate diets, coffee, etc. – do we warn people about that? We like cortisol during exercise as its release leads to mobilization of fatty acids from fat stores thus providing us with energy. After a workout where glycogen is depleted, cortisol is raised to spare glucose and then when you eat post-workout, it will offset this. Cortisol is NOT bad – it’s just a hormone. It is released in a pulsatile fashion and its release in the morning is part of what helps us get moving. CHRONIC high levels of cortisol can certainly be a problem and negatively impact the immune system, but acute responses are normal. Please stop vilifying hormones like cortisol and insulin simply because you read a headline and don’t understand all of their functions in the body. Transient increases during a short time of fasting or exercise or fasted exercise or a stressful situation, are not too much for our body to handle. If such a minor stressor (fasted exercise) was so detrimental, we would not have evolved to where we are today. As a matter of fact, one of the main benefits of intermittent fasting is its ability to boost the resiliency of cells in response to “stress.” Cortisol and fasting are often pitted against each other in certain fitness circles. Those who preach, “Beware of cortisol increases in fasting,” are typically using cherry picked studies that don’t accurately depict the discussion at hand or simply ignore the entire picture. For example, some of the common studies for those in this camp include one where the participants fasted for 5 straight days and cortisol increased. Well of course, why wouldn’t it? Your body is trying to spare glucose. This leads to clickbait-esque thinking…fasting = more cortisol and cortisol = bad therefore fasting = bad.”

    4. I agree with calorie cycling and ensuring that there is a higher intake after workout. But the following paragraph is very questionable:
    “However, don’t worry if you can only eat three meals per day. Just have breakfast early, have dinner late, and make sure that all of your meals have at least 20 grams of protein in them.”
    If you are eating 3 meals a day, you are much better off doing the opposite! Eat a late breakfast, early dinner and make sure that you eat the 3 meals four hours apart (say 11am, 3pm, 7pm) and fast the remaining to get the best of both worlds.

    • Shane Duquette on July 10, 2018 at 7:16 pm

      Hey RR, thank you for the long and thoughtful answer! You’ve raised some good points. Let me go through them.

      1. When doing these articles I think it’s more helpful to take the best possible argument on either side. You’ll notice that on the intermittent fasting side, I’m referencing guys like Martin Berkhan, Brad Pilon and Dr John Berardi, all of whom I have a tremendous amount of respect for. I’m familiar with their plans and when comparing intermittent fasting against eating more frequently, I’m assuming that in both cases the macros and nutrition quality are fully optimized. I’m comparing the very best intermittent fasting diet against the very best traditional bulking diet. Even then, intermittent fasting is not ideal for bulking. I don’t even think the best intermittent fasting advocates would disagree with that, as they tend to recommend intermittent fasting for cutting and general lifestyle, not bulking.

      2. I did mention that intermittent fasting has some interesting possible longterm health benefits. However, bulking is a short-term endeavour. I’ve spent around 18 months of my life bulking, gaining roughly 55 pounds of muscle during those months, and even those 18 months were split up with breaks. Now, goals accomplished, I do rather enjoy intermittent fasting… but still I wouldn’t recommend it to someone who was interested in building muscle quickly. If someone asks me how to bulk, I’m going to teach them how to bulk. When they’ve gained the 20+ pounds they’re after, then we can transition into a healthy long-term routine. Those two routines are somewhat different. Bulking means eating too much, lifting too hard, and prioritizing protein. Longterm health is about going back to eating the right amount, lifting a bit less intensely, adding in some cardio, more focus on fruits/vegetables, etc.

      3. It’s good to point out the misconceptions surrounding cortisol. It’s not a “bad” hormone, it’s a stress hormone, and just like with stress, the goal isn’t to get rid of it completely, it’s just to strike that proper balance. Yes, we want to stress ourselves both in the gym and elsewhere in life. No, we don’t want to be chronically stressed all the time. Where is the proper balance point for our specific goal? In this case, spending an extra 8-ish hours each day with elevated cortisol probably isn’t ideal, at least not for muscle growth.

      4. Intermittent fasting isn’t ideal for building muscle, so we don’t want to introduce intermittent periods of fasting into our bulking routine. You’re correct that after a few hours we can boost muscle growth by having a protein-rich meal, but that doesn’t mean that the previous boost has fully ground to a halt within four hours (as shown in the diagrams). It’s likely still better to spread those meals apart.

      Thanks again for the thoughtful comment, and let me know if you find any of those answers unsatisfactory or if you have any other objections 🙂

      • RR on July 10, 2018 at 8:06 pm

        Thanks for the quick and detailed response, Shane.

        On #1, I agree with you on the bulking part. IF likely causes muscle gain to be slower. I just disagreed on the part where you said IF causes more fat gain than eating frequently. It goes against the premise which you’ve also stated that IF is best for cutting.

        On #2, I totally agree. IF is not ideal for a short term endeavor of quick bulking. It’s more a long term health routine with slow and steady muscle gain as long as we eat caloric surplus. I’ve gained 10 pounds in 6 months of IF and I am okay with that pace given the health benefits. It depends on one’s priorities.

        On #3, I don’t think cortisol stays elevated for 8+ hours with IF. It’s more a case of acute short term increases while the hunger pangs come (which are less frequent as one does more IF). IF is proven to cause better sleep and that wouldn’t be the case if there was chronic cortisol spike.

        On #4, yeah I see your point. Goes back to #2 above as to what one’s priorities are.

        • Shane Duquette on July 10, 2018 at 9:08 pm

          My pleasure, RR!

          On #1, I think we’ve found the disagreement and mended it. I’m just talking about bulking in this article. Since there’s a calorie surplus when bulking, and the degree of the calorie surplus dictates the rate of weight gain, then if muscle gain is slower, more of that weight gain will come from fat. For example, if you’re gaining 1 pound per week due to your calorie surplus, better to be gaining muscle more quickly so that more of that pound is muscle. When someone is cutting, there’s no calorie surplus, and thus no risk of fat gain anyway. In this case, where there’s a calorie deficit, intermittent fasting is fantastic (and my personal preference).

          On #2—excellent. I hope I made it clear in this article that much of this comes down to personal preference. There are some fundamental aspects of muscle gain where there’s really no room for compromise: you need a good resistance training program, enough calories, enough protein, and enough quality sleep… but meal schedule is not a big deal. You can bulk just fine while intermittent fasting. This article was more for people looking to min-max their bulking plan, trying to get the most bang for their buck. But I wanted to make it clear that if someone is okay with slower results and prefers intermittent fasting, that’s no problem whatsoever. I don’t even think it will substantially slow progress.

          On #3, the study I referenced found that overall levels of cortisol were higher in the intermittent fasting group. That could be from a series of spikes. Either way, I’m not sure that’s a great thing while bulking. Probably better to limit added stress while your body is already making such a monumental effort to pack on muscle. Again, though, not the end of the world.

          Like I said earlier, I think we’ve largely solved the disagreement. In this article I’m writing about the best way to bulk—and not just to bulk, but to really build muscle as quickly and leanly as possible. For different goals, or for people with different timelines or priorities, things change 🙂

  4. Matteo on July 11, 2018 at 7:46 am

    This skinny guy wakes up every morning simply ravenous, so I would never be able to fast until noon. “Most skinny guys wake up without much of an appetite, making breakfast more of a chore than a treat.” Now if only I could match my stomach capacity with my appetite, I could eat a lot more than I do.

  5. Jason D on July 15, 2018 at 4:33 am

    This site is a favorite, and incredibly thorough! As a life-long ectomorph (slowly moving towards meso :P), and a certified personal trainer, I can see this info is spot on and very well analyzed! I’ve even picked up a few tips on meal strategy from you guys. I got your eBook; keep up the fantastic work, dude!

    With that said, I can’t tell you how many people – ecto or not – try to BS diet and just gloss over what calories do. It’s just as hard for us to hold weight as it is for the rest of the world to lose it! My clients laugh when I’m eating so much all the time…but they’re the first to ask “WOW! Are you on steroids now?!” 😛

    Keep up the good fight, gents!

    • Shane Duquette on July 15, 2018 at 4:41 pm

      Glad you’re loving the site, Jason! Thank you so much for the kind words.

      Always know you’re doing everything right when the steroid accusations roll in 🙂

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