How Fast Can You Build Muscle… Really?

how fast can you build muscleEverywhere you turn, it seems that people are making outrageous claims about how fast you can build muscle.

You see a book that promises gains of 18 pounds in just two weeks. Then you hear about a strength coach who claims that he put on 14 pounds of muscle in 5 days.

Pick up any of the popular fitness magazines and you’d be forgiven for thinking that building muscle is the easiest thing in the world.

There’s conflicting advice coming at you from here, there and everywhere, and you can’t figure out who, or what, to believe.

So how fast can you gain muscle?

The honest answer is I have no idea. And neither does anyone else. Muscle growth varies so much from person to person that it’s almost impossible to predict in advance how much muscle you’ll gain over a given period of time.

Read on and I’ll explain each of the factors affecting your rate of muscular growth, as well as giving you a rough idea about the sort of results you can expect to see after weeks, months and years of training.

1. Genetics

There are some variables that you can control, such as how you train and what you eat. But the variable that has the biggest impact on your rate of muscle growth is the one that you can’t do a damn thing about — your genetics.

Like it or not, some people build muscle very quickly, and will see impressive results after only a few months. Others, however, seem to make little or no progress at all.

The figure below is taken from a study where a group of otherwise identical guys (diet, training age, compliance, age, initial lean body mass) lifted weights for 12 weeks (the raw data was pulled from this research).
Gains in muscle mass in high vs. low respondersWhen the researchers looked at the results of the men who built the most muscle (high responders) and those who built the least muscle (low responders), they found roughly four times greater gains in muscle in the high versus the low responders.

The researchers then used gene profiling to look at microRNAs (miRNA) in tissue samples taken from both groups of men.

miRNAs are small, non–coding RNAs which, amongst other things, appear to play an important role in regulating protein synthesis (i.e. muscle growth) during resistance training.


miRNAs also appear to have an influence on something called satellite cell activation. Satellite cells surround your muscle fibers. They provide the building blocks for muscle growth.

While some of us have a lot of satellite cells, this doesn’t hold true for everyone. People who make rapid gains in muscle size have more satellite cells surrounding their muscle fibers, as well as the ability to expand their pool of satellite cells during training.

Bill StarrRecent research also shows a wide range of strength gains even in people following the exact same training program.

Subjects were grouped into high responders (those who made greater than 20% strength gains), medium responders (10-19% gains) and low responders (less than 10% gains).

There was an average increase in strength of 29% for high responders, 14% for medium responders and 3% for the low responders.

In other words, some people respond extremely well to strength training. Some will get “good but not great” results. Others will see almost no results at all.

Yes, I know it sounds like a bit of a cop out to point the finger at “bad genetics” when it comes to explaining away your slow rate of progress.

In many cases, a poor training program and diet are equally to blame for the fact that you’ve gained no new muscle since the Bush administration.

But like it or not, the fact remains that there are genetic factors outside your control that affect how fast you can build muscle, as well as the maximum amount of muscle you can expect to gain naturally.

And unless you’re willing to have your genes tampered with by a renegade scientist, there’s not a single thing you, me or anyone else can do about it.

2. The Law of Diminishing Returns

The greater your training age (i.e. the number of years you’ve been training with weights), the slower the gains are going to come.

In most cases, someone who’s been working out with weights for 10 years will build muscle a lot more slowly than someone who’s been training for 10 weeks.

Of course, the big problem with training age as a variable is that it assumes you’ve been using a sensible program for the entire length of time you’ve been training. And let’s face it, most people (me included) haven’t.

Someone who’s been “blitzing and bombing” each muscle group with 30 sets once every week for the last 2 years (not a great idea by the way) and gained little in the way of muscle may have roughly the same potential for growth as someone in their first year of training when they start training properly.

So it would probably make more sense to talk about your “ceiling of adaptation” or “upper limit” of what you’re capable of in terms of muscle growth. The closer you are to this upper limit, the slower the gains will come.

What is your maximum muscular potential? How big can you get naturally?

For a drug-free, genetically “average” guy, getting to a lean (8-10% body fat) 180 pounds is a significant achievement. If you can make it to 190 pounds while staying close to 10% body fat, you’re going to look pretty damn impressive.

And remember that bodyweight is relative. If you have 30-40 pounds more muscle than an average untrained man of your height and bone structure, you’re doing extremely well. That’s about as much as most people can realistically expect to gain over the course of their training lifetime.

Am I saying that 30-40 pounds of extra muscle is the absolute upper limit for every single human being that has ever walked on this planet? No. But I am saying that it’s going to be there or thereabouts.

If you want a customized estimate of the maximum amount of muscle you can build, take a look at Casey Butt’s Maximum Muscular Bodyweight calculator.

It’s based on equations that Casey developed during 6 years of research and analysis of data from drug-free champions both past and present, and gives you a pretty good idea of the maximum muscular bodyweight  (at roughly 8-10% body fat) that a drug-free trainee of your structure is likely to reach.

3. Body Type

Your rate of muscular gain is also going to scale up based on the size of your frame and the amount of muscle mass you have to start with.

Scientists from the Netherlands, for example, used something called the fat-free mass index to assign a group of men to either a “slender” (the typical “skinny guy” who has an extremely tough time gaining weight) or a “solid” (naturally muscular guys who just have to look at a weight and they grow) group. Both groups lifted weights twice a week for 12 weeks.

All the men put on muscle during the 12-week study. But the slender guys gained an average of just 0.7 pounds, compared to 3.5 pounds in the solid group. In other words, subjects in the “solid” group gained FIVE TIMES more muscle than those in the “slender” group.

Jusup WilkoszIf you have a large frame and sturdy joints, then you’ve got an advantage over someone with a smaller frame, as you’ll generally be able to lift more weight and deliver a greater training stimulus to the muscles each time you train.

One way to estimate frame size is to measure your wrist on the hand side of the styloid process, which is the bony bit on the outside of your wrist.

A wrist size of 19.5 centimeters and above indicates a heavy bone structure. A wrist size of under 16.5 centimeters is indicative of a smaller bone structure. A figure between those numbers indicates a medium bone structure.

Of course, this assumes that wrist size directly correlates with bone size throughout the body, which isn’t necessarily true for everyone. But as a rule-of-thumb, it gives you at least a reasonable idea. The bigger the man, the greater his muscular potential.

4. Testosterone

The natural level of anabolic hormones floating around your body (such as growth hormone, insulin and IGF-I) as well as the way these hormones are affected by how you train and what you eat has a big influence on both your rate of muscle growth and your maximum muscular potential.

At the top of the hormonal “pyramid” is testosterone. Where size and strength are concerned, testosterone is undoubtedly the “King Kong” of all the anabolic hormones.

For men, the normal level of testosterone in the bloodstream is somewhere between 350 and 1230 nanograms per deciliter (ng/dl).

If your average daily testosterone level is 500 ng/dl, you’re not going to make gains as quickly, or have the potential to build the same amount of muscular mass, as someone whose average daily testosterone level is 1000 ng/dl.

One way to bypass your natural muscle growth limit is to artificially enhance your body chemistry with the use of exogenous testosterone.

In fact, much of the confusion about how fast it’s possible to build muscle stems from the fact that a lot of the people you read about in the magazines or see on TV are taking drugs.

In this short clip from the documentary Bigger, Stronger, Faster, top fitness model Christian Boeving (you might have seen him in some of the old MuscleTech adverts) admits to using anabolic steroids since the age of 16.

To give you an idea what a big difference anabolics can make, I want to give you some numbers from a study that looked at the impact of testosterone injections (600 milligrams of testosterone enanthate every week) on muscle growth in a group of men aged 19 to 40.

Men combining testosterone injections with strength training gained 13 pounds of muscle in 10 weeks. This compares to a gain of just over 4 pounds in the placebo-plus-exercise group. Subjects who took testosterone and did no exercise gained around 7 pounds of muscle.

In other words, the men who lifted weights and took testosterone gained three times more muscle than the guys who lifted weights.

And the guys using testosterone and doing NOTHING gained 60% more muscle than the guys who trained with weights.

Think about that for a second.

The guys on testosterone and doing nothing built more muscle than the men lifting weights three times a week.

I couldn’t care less if you use drugs or not. We all have one body and should be allowed to do what we want with it. There are already plenty of people out there telling you how you should live your life, and I have no intention of becoming one of them

But I do think it’s important that you know what goes on “behind the scenes” so you can set goals for yourself that are both realistic and achievable. Otherwise you’re just going to end up feeling frustrated at the large gap between your expectations and your results.

5. Muscle Memory

Every time an actor gains a large amount muscle in preparation for a film role, there’s always a lot of buzz about how he did it.

Robert Downey, Jr., for example, weighed in at 151 pounds on the set of Sherlock Holmes. By the time he’d started filming Iron Man 2 three months later, Downey had gained around 20 pounds of muscle.

Twenty pounds is a lot of muscle to gain in just 12 weeks. What’s going on?

“He really rebuilt a lot of what he had for Iron Man 1,” said Brad Bose, Downey’s long-time trainer. “We rebuilt from 151 pounds to about 171 pounds.”

In other words, this wasn’t 20 pounds of new muscle. Downey was simply re-building old muscle, which is a lot faster than gaining it in the first place thanks to a phenomenon known as muscle memory.

Research shows that when a muscle is trained, detrained and retrained, there is a faster change in muscle size during retraining compared to the initial training period from an untrained state.



In many cases, the people in the before-and-after pictures you see in the magazines are fitness models who have spent a few months “slacking off” prior to getting their “before” pictures taken.

Because they’ve been in shape before, it’s a whole lot easier for them to regain their old physique than it is for someone who’s starting from scratch.

While I’m on the subject, if you’ve ever wondered whether some of those before and after pictures you see in the magazines are real or not, this is a short (68 seconds) video clip you might be interested in.

It’s taken from a documentary called Bigger, Stronger, Faster, which is worth watching if you haven’t seen it already.

Even though it’s old news to anyone who’s seen what really goes on in the supplement industry, a lot of people are surprised when they realize that this kind of thing actually happens.

6. Nutrition

Most people would agree that to build muscle, you have to eat. A diet that lacks adequate nutrients will mean a rate of muscle growth that’s less than optimal.

However, one of the biggest mistakes you can make is eating far more than you actually need in the hope that you’ll somehow force your muscles to grow more quickly.

Your body has a limited ability to build muscle, which is largely dependent on its capacity to create new muscle tissue from the amino acids (protein) in your diet.

You can eat all the food you want, but you can’t change the rate at which your body synthesizes new muscle protein. Taking in more nutrients than you can use won’t force your body to add muscle more quickly. All that’ll happen is that you get fat.

Imagine you own a factory that makes widgets.

If you don’t give the workers enough of the raw materials (i.e. food) they need to make the widgets as fast as they could, the rate of widget production will drop. So in that sense, an insufficient intake of nutrients will put the brakes on muscle growth.

What happens if you start to send more raw materials to the workers?

The rate of production will increase, but only up to a point. That’s because there’s a limit on the number of widgets the workers can crank out in a given amount of time. As soon as they’re working as fast as they can, sending more and more raw materials just becomes a waste.

In much the same way, you can’t force your body to grow simply by eating more. Adding nutrients to your diet will have a positive effect on muscle growth only until you reach nutrient saturation point. After that, additional calories will simply be stored as fat.

As you probably know already, there are plenty of people running around trying to convince you that they have “the secret” to gaining 50 pounds of muscle in six months or less.

But I’m pretty sure that a lot of them are using anabolic steroids and passing off their results as “natural.” Either that or they’re simply making it all up.

How fast did Arnold gain muscle?Even Arnold Schwarzenegger, who combined great genetics and a Herculean work ethic with a little pharmaceutical assistance, was very happy when he gained 25 pounds in weight over a 12-month period. Here’s what he wrote in Arnold: The Education of a Bodybuilder:

Many people regret having to serve in the Army. But it was not a waste of time for me. When I came out I weighed 225 pounds. I’d gone from 200 to 225. Up to that time, this was the biggest change I’d ever made in a single year.”

So if one of the greatest bodybuilders in history is saying that 25 pounds was as much as he ever gained in one year (and not all of this was muscle), what makes you think you can beat it?

If we take all of this into account, how much muscle can you realistically expect to gain over the course of a year?

In one Baylor University study, a group of beginners gained 12 pounds of muscle in 10 weeks using a 4-day split routine.


So in the best-case scenario (i.e. you’re an untrained guy in your late teens or early twenties), you can expect to gain somewhere between 2 and 5 pounds of muscle per month in your first few months of training.

On a related note, if you’re loading with creatine (20 grams a day for 5 days), or you eat a lot more carbohydrate than normal, you can gain lean tissue more quickly than the numbers of I’ve just given.

For example, you might put on 4-5 pounds of lean tissue in your first week on creatine and a high-calorie diet. But remember that “lean tissue” doesn’t necessarily mean muscle tissue, as stored fluid and carbohydrate also contribute to gains in lean tissue.

In addition, you won’t keep building muscle at the same rate indefinitely, and gradually your rate of progress is going to slow down.

In your first year of serious training you can realistically expect to build anywhere between 10 and 25 pounds of muscle.

Under the right conditions, guys with a large bone structure and good genetics may see gains of up to 25 pounds, while smaller men with less favorable genetics will find that 10 pounds is about the limit.

In year two, we can cut those numbers in half, giving you a gain of 5-12 pounds. In year three, the gains will be halved again, giving you 3-6 pounds of muscle. Gains in the average female are roughly half those seen in men, mainly because they don’t have as much testosterone in their system.

I know this might not sound like much. But I guarantee it will make a huge difference to the way you look.

If you enjoyed this post, there’s a good chance you’ll also like Truth and Lies about Building Muscle: 10 Muscle Myths Debunked By Science.


SHAMELESS PLUG: Muscle Evo wraps up all my best ideas and advice into a complete science-based training program that you can use to get the "lean, strong and athletic" look without spending unnecessary hours in the gym. Click here to learn more about Muscle Evo.



About Christian Finn

Christian FinnChristian Finn holds a master's degree in exercise science, is a certified personal trainer and has been featured on BBC TV and radio, as well as in Men's Health, Men's Fitness, Fit Pro, Zest, and Perfect Body magazine. You can contact Christian using Facebook, Twitter, Google+ or via e-mail.