What is a bulking diet?

The 3 best ways to build muscle as a skinny guy, and the science behind how fast you can gain weight as a beginner

If you speak to anyone who has successfully gained weight as a skinny guy, they’ll usually talk about what they ate being the key to their success.

Although other factors like workout program, lifestyle change, sleep quality and rest all play their own huge parts in bulking up as a skinny guy, the reality is: without a solid bulking diet in place, you’d struggle to gain any significant mass that shows that you workout.

But what diet should you follow to build muscle?

Nutrition can be overwhelming…

Diet fashions and fads are constantly changing and evolving.

Every few weeks it feels like we’re told to replace one thing with something else.

But it doesn’t need to be like that.

This bulking guide is here to cover pretty much everything you’d want to know about the basics of bulking diets, once and for all. So that you can gain the muscle you’re after without all the faf.

Don’t worry…

Nutrition can be pretty simple if you focus on the fundamentals, and that’s exactly what we’re going to give you in the next few chapters.

If you want to go from struggling to see any results at all, to finally putting on those pounds and beyond, read on!

Bulking diets aren’t hard if you get these two things right:

  • Consume enough calories to create a caloric surplus (i.e. past what it takes to maintain your weight)
  • Eat a high-protein diet to encourage muscle growth (and don’t worry, it’s not all chicken and broccoli)

However, there’s a lot more to bulking diets than that.

What does it mean to bulk?

Bulking is a phase of consuming a lot of calories, and doing a workout program geared towards gaining muscle mass.

For some it’s full-on “let’s eat everything you see”, and for others, it’s a slight increase in calories while trying to keep gaining fat down to a minimum – we’ll get into the different kinds in just a second.

As a guy struggling to gain weight, it’s typical that a 10-20% increase in calorie intake is necessary to tip the scales and gain weight (study).

This typically happens around the time where extra layers of clothing are worn, and you’re not so concerned about achieving cheese-grater abs – aka winter! 

However, if you’re not a bodybuilder, and you’re a skinny guy wanting to build muscle then bulking season is any time of the year, and that means it’s right now.

Chances are if you aren’t stoked about your current size and want to be bigger, and your fat levels aren’t too high (more on that in a second) you’ll want to follow a bulking diet.

The three approaches to bulking diets

The S2S bulk: This is what we’ll be talking about today, in more detail. It’s the line between good solid nutrition habits, and getting in enough calories to grow. (study)

Unlike traditional (or dirty bulking) we’ll be guiding you through strategies that can help you if you’re someone that doesn’t have a mouth like a gullet.

The dirty bulk: This is taking things up a notch. To the point of eating, even more, no matter the quality or “cleanness” of food in an attempt to gain as much mass as possible, regardless of the fat-gain that comes. It works wonders for muscle and strength gains, not so much for guys who don’t want to spend 3+ months cutting afterwards (study, study)

The lean-bulk: This one is much harder to do, and requires a little more patience and willpower. From our experience, it requires being just on the surplus side and training intensity. You’ll be gaining muscle slowly, but as the name suggests it’ll be muscle without fat, meaning every bit of weight added to the scale is muscle (more or less).

The positive though, is that if you’re an ectomorph and a beginner, your “newbie gains” will allow you to follow an S2S bulk or even a dirty bulk and still keep fat-gain to a minimum early on. Disclaimer: this varies person to person, and there is still the threshold of being a lean guy, and being a lean-fat guy to consider – so choose wisely

Before we go ahead and dive more into the bulking diet, you should know it isn’t the only part of the equation of building muscle.

Other things that matter are your workout program, your sleep, stress levels, habits and a whole host of other things.

The main thing you need, other than a bulking diet, is that you have a workout that’s going to help you build muscle. Without one, even a skinny guy will struggle to gain weight, and if you do, it’ll be all the wrong places (leading to the less ‘swipe-rightable’ skinny-fat look).

Although your body doesn’t really know the equipment you’re using (dumbbells vs barbells vs cables – study), you’re going to struggle to lift heavy enough (with enough progress and intelligent programming) as a skinny-guy to build muscle in the shortest time possible. For that reason, I recommend using weights at a bare-minimum.

This can be a home workout, with some adjustable dumbbells or a home bench set up. If you have access to the gym, then you can use things like machines and cables within for variety.

But either way, if you want to build a solid foundation of muscle and strength, it starts with dumbbells (or a barbell) and your bodyweight.

Don’t expect to gain muscle just by chugging protein shakes after any old workout.

But if bulking is about gaining weight (preferably muscle) then what else is there?

Cutting Vs Bulking Vs Maintaining

These are all often talked about in the bodybuilding space.

Although they can seem a bit confusing, and sometimes things go beyond this like recomping, and contest prep, the majority of people fit into these three categories:

  1. Bulking – We’ve covered this. It’s the stage of gaining weight.
  2. Maintenance – This is when you eat enough to preserve your current bodyweight. You’re not gaining any weight, but you’re not losing any either.
  3. Cutting – This is when you’re under your maintenance calories. Because of this, you’ll be losing weight. If you eat correctly, it’ll be fat loss.

These are usually done in several phases.

How to do a bulking diet plan

There’re many areas that make up a successful bulking diet.

All of these are covered in the following chapters, step-by-step.

They’re also listed in the order of importance, similar to the graph above. So if you’re stuck on which ones to really get started on, we’ve got you covered.

Start with getting in a surplus of calories and enough protein to promote muscle growth.

Can I build muscle and lose fat at the same time?

Chances are, if you’re starting out, and haven’t made much progress in the gym; then you possess some kind of magic right now…

This is called “newbie gains” (study).

Newbie gains are when you’re able to have major muscle and strength increases. It happens to someone who has little to no previous weightlifting experience or no luck with weight training that leads to muscle growth.

Not only that, but you’re also able to do something that is usually extremely difficult. You’re able to build muscle and lose fat at the same time (otherwise known as recomping) or gain a lot of mass with very little fat gain.

Why makes newbie gains possible?

Here’s the quick rundown:

When trying to build muscle, we want to maximise protein synthesis (build-up of protein) vs protein breakdown (the lose of protein, which as you’ll learn isn’t all bad).

When you’re new to weightlifting, training spikes muscle protein synthesis at a much faster rate (study). It doesn’t take much to do it either. Although the better your program, the better the results will be.

The thing that makes this happen is something called myonuclei.

(image Inspired by this article)

It’s the myonuclei that regulate the process of protein synthesis.

As exercise physiology Greg Nuckols puts it:

Myonuclei are the “control centres” of a muscle fibre. Muscle size is ultimately determined by how many myonuclei a muscle fiber has. There is a maximum area they can “oversee,” and once they reach that limit, you stop growing unless you can add more.”

– Greg Nuckols, exercise physiology (source)

That means that building muscle for those starting out comes down to:

1. Filling out your nuclear domains with muscle.

When you’re new to lifting, your muscles only have a few nuclei in them. However, we have the ability to add more to our muscle fibres, which allows us to get bigger.

When you first start bulking, your muscle fibres will expand rapidly to the limit of their nuclear territory, causing muscle fibres to grow up to 27% before hitting their limit (study).

Once most reach this point, your results plateau (from extremely rapid growth to slower growth).

That’s when the next part comes in.

2. Adding new nuclei to expand your domain.

This doesn’t just happen in separate stages.

This is happening, while stage one is happening too. As you gain new nuclei, you will need to fill out your now bigger territory.

We do this by growing satellite cells and then merging them into your muscle fibres. This allows us to have another growth spurt, of 10+ lbs of muscle.

The following stages are post-newbie gains and when things start to slow down.

How quickly can you gain muscle as a newbie?

Many people, like Vice magazine, believe you can only build 8-9 lbs of muscle after three months of hard training (source).

The independent seems to state something similar:

“With all of those things considered, the average man can gain about one to two pounds of muscle per month and the average woman up to one pound per month.” (source).

And one study showed that participants were able to gain 7 lbs within three months (study).

However, they’ve gotten quite a bit wrong there.

We don’t need to look far to see proof of that:

Like Tim Ferris’s ‘Geek to Freak’ experiment where he gained 34 lbs in just four weeks (source) or Nate Green’s ‘Bigger Smaller Bigger’ experiment:

Sure these are outliers. However, we’ve seen that it’s common to get results in the range of 20-30 lbs within 90 days.

If you’re a skinny guy that’s never built muscle before, then you’re in a better position than anyone to start, because you’re so far from your muscle growth potential.

Science has proven it:

  • One study showed that newbies were able to gain on average 12 lbs of muscle, within ten weeks (study)
  • Another showed that newbies beginners could gain 9 lbs of muscle in their first eight weeks. (study)
  • And another showed that it was possible to gain 15 pounds of muscle in the first 12 weeks (study)

And these results are without a workout or diet that’s optimised for maximum muscle growth!

It’s all about how far away from your genetic potential you are.

If you’re on the skinnier side of life, like I was, then to reach your genetic potential, it’s going to take a lot of muscle growth (sometimes 40-60lbs over several years).

Yet, if you already have decent genetics (the kind that gains weight relatively easy) then it’s going to be a much slower, and simpler process (study)

This is a handy model to have in mind:

Muscle growth for ectomorphs (source)

Pre-newbie gains (first year): This is when a skinny guy can gain up to 40 pounds in this first year of training. 20+ pounds gained in the first three months alone. 

This stage lasts until the skinny guy has as much muscle on his frame as a regular untrained man. After this stage, a skinny guy will start making progress similar to an average newbie.

Early-stage newbie gains (months 0–3): The average guy can expect to gain up to 15 pounds of muscle within the first 90 days when following working out.

Depending on how far you are from your genetic potential and skinny you are, you can expect to gain more (sometimes 20-25 lbs)

Late-stage newbie gains (months 3–12): After your initial muscle growth spurt, you’ll notice a struggle.

It may take another 6–9 months to double that initial amount of muscle mass that you gained. For the average guy, that might mean 20–25 pounds within 12 months, and for a skinny guy, might bring gains in excess of 40 pounds within his first year (in cases where people are starting super skinny).

As expected, after one year, the rate of muscle growth starts to rapidly decrease:

Amount of muscle growth per year

This is due to something called repeated bout effect (study) which simply means, the more we do something, the more we get used to something, and the fewer results we get.

To gain so much mass fast, you might be wondering if it’s healthy, or if there are any risks.


The body is designed to only build the muscle that it needs. We don’t need the insane amount of muscle that we see on roided-up meatheads, which is why for natural lifters, there’s a limit.

Is it possible to still gain muscle after years of training?

Sure. But it’s going to a tough time to earn every single pound of it.

Is following a bulking diet healthy?

Kind of a loaded question, don’t you think?

Bulking as a whole can be both good and bad for your health, depending on how you do it.

As I’ve mention, there are several kinds of bulking:

There’s the kind I recommend which requires getting enough calories in, from a mix of food groups. It also includes lifting weights which will get you building muscle, getting strong and dropping body-fat. All things that are healthy.

Then there’s the dirty bulking side, and balls-to-the-wall training culture. This means eating a lot of junk food, that can put your health at risk (although skinny guys might not “see” it) and training recklessly which can cause joint issues and may weaken your immune system (study).

A healthy argument for bulking

The benefits of lifting weights and having muscle mass are greatly researched, from helping reduce the risk of cancer (study) to reducing the risk of a heart attack (study).

There’s also the fact that it can improve your mental health (study) and increase insulin sensitivity (study).

It can also help with mobility (study), improved posture (study) and is even recommended by the World Health Organization (WHO), with cardio.

So when done right, following a bulking diet (one that leads to actual muscle growth) has a lot of benefits to offer.

An unhealthy argument for bulking

Then there’s the other side. The one that you likely think of when it comes to extreme bulk up diets.

Now, if you’re someone who gains fat easy (skinny-fat), then bulking has to be played more on the careful side, when going to extremes.

It can increase your risk of developing diabetes (study), increase the risk of cardiovascular disease (study) and harm your joints (study).

It can also increase stress/anxiety (study) and mess with hormones such as testosterone and estrogen (study, study).

Reading a list like that might seem scary. However, all of these are less to do with following a diet designed to build muscle, and all to do with overeating in general.

If you’re a beginner, who’s relatively lean already, then you have a whole host of benefits to gain. The main thing to focus on is to make sure you follow a weightlifting program that’s intelligently designed to build muscle. Do that, and you’ll have very few downsides and a lot of benefits in both how you look, and how you feel.

How do you do a bulking diet successfully?

It’s a big topic.

Muscle-building nutrition can be overwhelming.

“New” diets are popping up on the shelves all the time.

News articles are scaring people with “danger” headlines.

However, it doesn’t need to be like that.

Nutrition can be pretty simple if you focus on the fundamentals, and it’s these that you’re going to learn about over the next few chapters.

Remember, not everything is linear, but with the right program, you can gain weight.

This guide is designed to help you go from gaining nothing to seeing results weekly. 

It’s here for the skinny guys who are ready to stop losing motivation and start winning confidence.

Let’s dive in.

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