The Science of How to Build Muscle: Full Guide (2023)

Contents

  • Intro:How much muscle can I gain?
  • Intro:Workout motivation
  • Starting Out:Gym preparation
  • Starting Out:Supplements
  • Workout Plans:Workout plans
  • Workout Plans:Tracking gains
  • Eating Properly:Calorie requirements
  • Eating Properly:What to eat

Most bodybuilding advice is misleading

This handbook is the result of a year'sresearchinto what the latest science showsis the most efficient way to build muscle.

It's for both men and women. It's primarily for beginners, but there's plenty of science-backed advice for intermediates too.

I wrote this guide because much of the casual weightlifting advice is unsubstantiated or misleading. I can't blamebloggers for it, because some of the facts in this guide have not been broadly published outside of the scientific literature.

As a result, this handbook contradicts some popular bodybuilding recommendations. Throughout this handbook, I support my claimsby citing studies and showing you how to measure your weekly gainsso you can confirm you're growing for yourself.

Speaking of growth, if you're starting without muscle, you can grow it fast if you're diligent about eating, exercising, and sleeping.You can gain up to 12-15lbs (6.8kg) of muscle in 3-4 months when closely following a researched program. (Afterward, muscle gains slow drastically.)

These results areachievable for every healthy man and woman. Having “bad genetics” is not a thing preventing beginnersfrom gaining muscle. That's another myth.

In addition to thoroughly citing research, this guide is also comprehensive. I dislike tutorials that provide 75% of what you need to know then leave you with questions.

We'lllearn what the research says about:

  • How to eat to gain muscle mass.
  • The most effective exerciseroutines.
  • Measuring your weekly muscle gains.
  • Overcoming plateaus.

Inspired? Good. If you weren't willing to spend 1–2 years in the gym to get results before now, be excited because you cancompress beginner gains into 4 months.

Oh, and Ihave nothing to sell you. This handbook is free. There's no promotion.

In a year from now, you'll wish you started today.
—Karen Lamb

Who's Julian Shapiro?

I spend thousands of hours deconstructing how things work. I compile my insights into free handbooks like the one you're reading. Over a million people read them annually. Insights that don't make it in are shared on Twitter.

Outside of writing, I invest in startups through my seed fund and Carveout. Previously, I coded the world's most popular web animation engine, Velocity.js, and Ifounded Demand Curve, the largest educator in startup marketing. More here.

Bodybuildingadvicefor everyone

I'm coveringthe universal principles of how to build muscle.

Ifyou're a beginning bodybuilder, you'll learn to add up to 15 lbs (6.8 kg) of muscle. If you're an intermediate, you'll learnhow to break through plateaus. If you're looking to get stronger instead ofbigger, most of this handbook applies.

My research process:I cite research when possible, but I don't blindly follow a study’s conclusions. Not all studies are well designed, so Itry to find multiple studies to support claims. I then experiment with findings and compare them against each other.

How muchmuscle can I gain?

Let’s develop a realistic expectation so you’re not disappointed with your results.

The total size you can naturally reach is relative to how large your skeleton is (study). Are you a broad-shouldered man with thick wrists and ankles? Expect to get way past a 3” (7.5cm) gain in arm size if you work out for a long time.

Are you a smaller 5’4” (1.65m) person with narrow hips? Even if you worked out for decades, you likely wouldn't get as muscular as a larger-framed person could.

To begin, selectyour gender to display the appropriate information:

Male physique examples

Take a look at the physique below.You can downloadthe image and glance at it whenever you need motivation to continue working out:

The Science of How to Build Muscle: Full Guide (1)

Want to know how long it takes to build muscle? The image aboveis a realistic reference for the mass an average-sized male attains after 4 months of working out.

Charles looks healthy, he has the muscle mass most women prefer, and he didn’t need steroids to get there.(If you’re already much bigger than this model, this guide can hopefully help you overcomeplateaus to continue getting bigger.)

(If you are elderly or suffering from certain diseases, you may be at a disadvantage. Talk to a doctor before weightlifting if you're concerned about safety.)

If you’re instead starting from frailty, gaining muscle for 3 months can get you here:

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That's 90 days away. Because you build muscle more quickly when starting out.

Finally, if you’re already big, you can level up with enough hard work:

The Science of How to Build Muscle: Full Guide (3)

Note:Getting significantly bigger than the physique above requires years of work. It gets harder to continue growing after your first few months of bodybuilding. When you enter this stage, you may gain muscle at a rate closer to just ~2 lbs (0.9kg) per year.

Recognize that all these guys have low body fat, which better reveals their muscle mass.

If your motivation for getting hugeis having women find you more attractive, here’s a reality check: Most women find the physiques shown above more attractive than the huge physiques found on the covers of muscle magazines. Studies of women’s preferences are convincing:¹² Most compare men with huge physiques to “...girls wearing too much makeup. It's too much of a good thing."

In other words, it appears the majority of women prefer the right side to the left:

The Science of How to Build Muscle: Full Guide (4)

(Still don’t believe it? Just poll your female friends.)

Steroids

Despite this reality check about women’s tastes, you're probably still curious how some people—like Hollywood superheroes—gethuge. Well, somecelebrities playing superheroesare or were at some pointonsteroids,insulin, orHGH—the use of which results in health problems.Plus, some have uniquely broad frames.

It is otherwise unrealistic to go from average toThor Size™ in under a year.

A discussion of what is natural to attain should referto "natural bodybuilding competitions." You can Google for images. Their contestants are not permitted to use steroids. However, remember that their muscle mass isaccentuated bytans, vascularity, low body fat, and having done push-ups right before walking onto the stage. They also have great genetics—big frames. And they've put in years of incrediblyhard work.

But here's thetricky part: “Natural” doesn’t always mean you can’t take other substanceslike HGH and insulin, which benefit muscle growth. (You can read amateur breakdowns ofcheatinghere andhere. While not investigative, these reports present evidence for how easy it is to game competitions.)

What exactly do the results of steroids look like? Well, the model below has chest and shoulder muscles that are particularly large relative to his frame. If your goal is to look like him, you're likely not getting there naturally.

The Science of How to Build Muscle: Full Guide (5)

Male maximum muscle size

We still haven’t answered the question of how big we can naturally get.

Here's your answer: ResearcherCasey Buttperformed a fascinating analysis on the muscle size of the world’s top male bodybuilders (source,study).

He used data from the pre-steroid bodybuilding era, which means it better reflects how muscular males can get naturally. We'lluse his results to approximate the maximum size we can weigh at10% body fat.

I’ve turned Casey's formula into a calculator below. This is applicable to men only:

Height — (move slider)

Ankle circumference — (move slider)

Wrist circumference — (move slider)

Maximum weight at 10% body fat
0.00


Maximum flexed arm size at 10% body fat
0.00

To measure the circumference of your ankle and wrist, wrap body tape around the parts indicated in the images below:

The Science of How to Build Muscle: Full Guide (6)

Female physique examples

Want to know how to build muscle as a woman? The same way a man does.

Here are two women with low enough body fat that you can clearly see their muscles:

The Science of How to Build Muscle: Full Guide (7)

The Science of How to Build Muscle: Full Guide (8)

In most people's opinion, the first woman isthin (look at the frailness of her arms) and the second woman isfit. (If you're looking for more inspiration, seehereandhere.)

Notice I’m not using the word “toned," which isn’t a thing. When people use the word “toned," they’re referring to the combination of (1) being thin enough that muscle definition is visibleand (2) having muscles to begin with.

You might not want to get as muscular as the second woman, but getting just halfway there will still make a noticeable difference in your physique.

The Science of How to Build Muscle: Full Guide (9)

Women's muscle gain

The limiting factor to how big you can get is the broadness of your skeleton (study). So if your body is on the smaller side (e.g. high school teenager), it will be improbable to reach the same maximum muscle mass as someone much bigger than you. In other words, the average woman will ultimately gain less muscle than the average man.

However, there's research showing that women develop muscle at the same rate as men (study,study,study).(Hat tip to Menno Henselmansfor compiling this research.)The difference is that women start with less muscle mass on average and ultimately gain less.

Yes, men have more testosterone, but testosterone is less important to the female muscle development process. In fact, women benefit from higher levels of IGF1 growth hormone, which is critical to muscle growth (study,study).

While there are fewer muscular women in the world, that’s perhaps a reflection of fewer women working to become very muscular. It’s not necessarily a reflection of it being significantly more difficult for women to see progress.

It’s important you understand that you're not at a disadvantage when bodybuilding because thinking otherwise can deter your progress. For example, onestudy examined the opposite scenario, where men were tricked into thinking they were taking steroids when they weren’t, and they consequently lifted 350% more in weight (study,study)!This suggests your confidence in the gym plays a critical role in how much you can lift.

Enthusiasm is more important than skillbecause the critical element in developing expertise is the desire to practice.
—Gretchen Rubin

How long does it take to build muscle?

Beginners can likely gain a couple inches on their arms within 90 days. You'll likely see additional noticable gains for another 2–3 months.

After 6 months, you typically gain more slowly—perhaps around 2lbs (0.9kg) per year.

Workout inspiration

Before we get to the workout programs and how to eat to build muscle, let's tackle the excuses stopping you from starting in the first place:

  • Have a history of not following through?Identify the person you respect most in life—someone who you don't want to think of you as a quitter. Tell them about your 90 day fitness goal and ask them to hold you to it. Create a calendar event for 3 months from now and include them in it.
  • Too lazy to commute to the gym?I'll soonexplain how to work out from home.
  • Have a hard time scheduling workouts?Wake up an hour earlier than normal and work out in the mornings before your day kicks off.
  • Don’t have the time?Getting startedonly requires ~1 hour three times a week.
  • Are you embarrassed to go to the gym?Pay for a couple training lessons at a local gym so you can learn proper form.
  • Afraid you don't have the talent? Basic bodybuilding requires zero talent. You don't have to be an athlete. If you can put food in your mouth and lift your groceries, you can lift weights. Assuming you don't have complicating medical conditions, in which case remember I'm not a doctor.
  • Don't like lifting weights? Wish you could just do body weight exercises? Most people who see quick results get addicted to them and enjoy sticking with it. Hopefully a handbook like this one can help you see those results.

So stop procrastinating. Let's get this done.

Bodybuilding program preview

For as long as you want to continue gaining muscle, this program requires you to go to the gym three times per week for 60 minutes. Once you’ve reached your target size, you can switch to a maintenance plan of two 40 minute weekly sessions.

Here’s the breakdown of this handbook:

Prep Week

  • Buy your workout accessories.
  • Take your starting photos.
  • Get into the habit of sleeping enough.

Workouts

  • First 2 months: Start with low-volumeworkouts with non-intimidating exercises anyone can do—even with just dumbbells. The workouts aren't too long.
  • 2 monthsto infinity: This plan consists of a higher volume and intensity of exercise, which will likely be necessary for your muscles to grow further.

On pages 3 and 4, there are cheatsheets you can download that summarize this entire guide. See the bottom of your screen for quick navigation links.

Medical disclaimer

After thisdisclaimer, the handbook begins.

You are not on the website of a medical doctor, nutritionist, or registered dietitian. The opinions expressed on this website, including texts, images, and videos, are generalized. They are presented “as is” for informational purposes only without warranty or guarantee of any kind. Julian Dot Com, LLC (“we”, “our”) makes no representation and assumes no responsibility for the accuracy of information contained on or available through this website, and such information is subject to change without notice. We arenot liablenor claim any responsibility for any emotional or physical problems that occur directly or indirectly from reading this website. We are of theability and use of conversation as perarticles 9 and 10.

You are encouraged to confirm information obtained from or through this website with other sources. Our content is not a substitute for qualified medical advice. The supplement summaries on this website may not include all the information pertinent to your use. Before starting a diet, taking new supplements, or beginning an exercise program, check with your doctor to clear any lifestyle changes. Only your doctor can determine what is right for you based on your medical history and prescriptions. Not us.

Never disregard or delay professional medical advice or treatment because of something you read on this site. In case of medical emergency, contact a doctor or call 911 immediately. Again, you are not receiving professional medical advice.

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