Since you’re reading an article about how long it takes to build muscle, I’ll assume a few things are true about you.
First, you’re trying to put on some muscle, and you want to know how quickly it’s going to happen. You’re willing to put in the time and effort, but you’re impatient. You just want to know what to expect in return for all your hard work in the gym.
Problem is, asking how long it takes to build muscle is a little like asking how long it takes to get from one side of town to the other.
Are you planning to walk, cycle, drive or take the bus? What time of day are you travelling? What’s the traffic like?
In other words, there is no single correct answer that will apply to all people, all of the time.
It’s much the same story when it comes to muscle growth. The length of time it takes to build muscle depends on how much muscle you’re talking about and who’s doing the building.
However, what I can do is give you a rough idea about the sort of results you can expect to see after weeks, months and years of training.
Knowing approximately how long it takes to build muscle will stop you wasting time, effort and money running around in search of some magic pill, diet or training program that’s making promises it can’t deliver.
But to repeat, nobody can tell you how long it’s going to take to build muscle, because they don’t know.
That’s because muscle growth varies so much from person to person that it’s almost impossible to predict in advance exactly how much muscle you’ll gain over a given period of time.
So what makes some people respond so much better to training than others?
The Hard Truth About Genetics and Muscle Growth
Some lucky folks put on muscle relatively quickly when they start lifting weights. For others, the results come much more slowly, even if they lift and eat the same.
The figure below comes from a study where a group of guys with a similar build, age, and training history lifted weights for 12 weeks [1, 2].
When the researchers looked at the results of the men who built the most muscle and those who built the least muscle, they found roughly four times greater gains in muscle in the fast versus the slow responders.
To put it another way, you and a friend of a similar build could follow exactly the same training program and diet for the next three months.
But individual variations in the rate of muscle growth mean that he might gain eight pounds of muscle. You, on the other hand, could gain just two pounds.
Research also shows a wide range of strength gains even in people following identical training programs .
Subjects were grouped into fast (those who made greater than 20% strength gains), medium (10-19% gains) and slow responders (less than 10% gains).
There was an average increase in strength of 29% for fast responders, 14% for medium responders and 3% for the slow responders.
In other words, some people respond extremely well to strength training. Some will get “good but not great” results. Others will respond a lot more slowly.
On a related note, it’s worth pointing out that gains in strength will outstrip gains in size when you first start lifting weights. You’ll get stronger far more quickly than you gain muscle. That’s because not all of those strength gains are driven by an increase in muscle size.
Rather, your neuromuscular system, the “chain of command” that transmits signals from the brain to the muscle, is doing a better job of using the available fibers in a given muscle. The fact you’re getting stronger doesn’t mean that muscle is being built at an equivalent rate.
Doubling the amount of weight you’re able to lift in a given exercise doesn’t mean that the muscles involved in lifting that weight have doubled in size. Nor does it follow that increasing the size of a muscle by 100% will produce an equal gain in strength.
How Genetics Affect Muscle Growth
Scientists have identified many factors that influence the variability in muscle growth from person to person .
They range from the number of capillaries, which deliver nutrients and growth-promoting hormones to your muscle fibers, to the thickness and pliability of the connective tissue that surrounds those fibers.
Let’s start with satellite cells. As the name suggests, satellite cells hover around your muscle fibers, waiting to be called into action to help those fibers repair and grow.
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.
In one study, subjects trained their legs three days a week for a total of four months . At the end of the study, the researchers analysed the training logs of each subject, and found no difference in training intensity, volume, or adherence to the program.
Despite this, there were wide differences in muscle growth from person to person.
“At the end of the training the subjects fell rather neatly into three groups,” explains David Epstein in his book The Sports Gene: Inside the Science of Extraordinary Athletic Performance.
“Those whose thigh muscle fibers grew 50 percent in size; those whose fibers grew 25 percent; and those who had no increase in muscle size at all.
“Even before the strength workouts began, the subjects who would ultimately make up the extreme muscle growth group had the most satellite cells in their quadriceps, waiting to be activated and build the muscle. Their default body settings were better primed to profit from weight lifting.”
Why Fiber Types Don’t Matter
Generally speaking, muscle fibers are lumped into two categories: slow twitch and fast twitch.
The fast twitch fibers are generally bigger and, as the name suggests, contract more quickly than their slow twitch counterparts.
It was once believed that some people have a greater potential for muscle growth because they start with a different allotment of muscle fibers.
The more fast twitch muscle fibers you have, the faster your muscles will grow. If you’re unfortunate enough to be lumbered with lots of slow twitch fibers, you’re doomed to grow more slowly.
At least, that’s what we used to think.
In fact, studies show that pre-training distribution of fiber types don’t differ between fast and slow responders to resistance training.
In one study, subjects were grouped into slow, medium and fast responders based on the amount of muscle they gained after 12 weeks of training . The ones who gained the least amount of muscle started out with almost exactly the same proportion of fast twitch muscle fibers as the guys who gained the most muscle.
Researchers from the University of Alabama at Birmingham report much the same thing . The distribution of muscle fiber types at baseline was no different across slow, medium and fast responders to 16 weeks of weight training.
Another study found that both the slow and fast twitch muscle fibers grew at much the same rate during 10 weeks of weight training .
In fact, subjects who trained with lighter weights and higher reps (30-40 reps per set) saw their slow twitch fibers increase in size by an average of 30%. The fast twitch fibers, on the other hand, grew by just 18%.
However, the difference in growth between the two fiber types wasn’t statistically significant, and the overall evidence is still very mixed as to whether it’s possible to target fast twitch or slow twitch muscle fibers with different styles of training.
In short, we may have underestimated the growth potential of slow twitch fibers . While they may have a lower ceiling for hypertrophy than their fast twitch cousins, they can, given the right stimulus, make a substantial contribution to gains in muscle mass .
In any case, the number of fast and slow twitch muscle fibers that you start out with doesn’t seem to explain why some people respond better to weight training than others.
The Fuzzy Link Between Testosterone and Muscle Growth
Testosterone levels vary naturally from person to person. One guy might have testosterone levels of around 1000 nanograms per deciliter of blood (ng/dL). For someone else, it might be in the range of 500-600 ng/dL.
In days gone by, I would have told you that more testosterone equals faster muscle growth.
That is, if your testosterone levels are hovering around the higher end of the normal range, you’ll have an easier time gaining muscle than someone with naturally lower testosterone levels.
Put differently, someone with a testosterone level of 1000 ng/dL will gain muscle faster than someone with resting levels of 600 ng/dL.
However, the link between testosterone and muscle growth isn’t as straightforward as was once believed.
We’ve known for a while that any temporary surge in post-exercise testosterone levels has little impact on the amount of muscle you gain over time .
However, within certain limits at least, resting testosterone levels don’t appear to have much to do with muscle growth either.
In fact, research shows that guys who built the most muscle after 12 weeks of weight training weren’t the ones with the highest testosterone levels, but the ones with more androgen receptors .
Why do androgen receptors matter?
For testosterone to do all the things we know and love as far as muscle growth is concerned, it needs to interact with muscle tissue. And it does that via androgen receptors. One of the ways androgen receptors respond to a hormone like testosterone is by signaling muscle cells to increase the rate at which new muscle protein is laid down.
Guys who built the most muscle didn’t have higher testosterone levels. What they did have is more androgen receptors in their muscles than subjects who gained the least muscle. This meant their bodies were able to make better use of the testosterone that was available.
In other words, it wasn’t testosterone levels that predicted muscle gains, but how sensitive your muscles are to that testosterone.
Think of it like a car, with testosterone as the engine and androgen receptors as the tires. If you’ve got a powerful V8 engine but cheap tires, you’re not going to be able to make full use of that power. Likewise, you need those androgen receptors to make full use of the testosterone that’s in your system.
All of which begs the question:
If testosterone levels aren’t linked to muscle growth, why does injecting yourself with testosterone make your muscles grow faster?
Anabolic drugs work because they take your testosterone levels outside of their normal physiological range and keep them there, night and day, for weeks, months (sometimes even years) on end.
Using anabolic drugs to raise your testosterone levels above their normal range has a big impact on how long it takes to build muscle. They can generate an impressive rate of growth in a relatively short period of time, even if you don’t set foot in a gym.
Much of the confusion about how long it takes to build muscle stems from the fact that some of the people you see online or on TV are taking drugs.
In this short clip from the documentary Bigger, Stronger, Faster, former fitness model Christian Boeving admits to using anabolic steroids since the age of 16.
Truth is, anabolics can make a massive difference to the length of time it takes to build muscle, as well as the maximum amount of muscle you’re able to build.
Here are some numbers from a study that looked at the impact of weekly testosterone injections (600 milligrams of testosterone enanthate) on muscle growth in a group of men aged 19 to 40 . They weren’t untrained beginners, and had some experience with lifting weights, but weren’t bodybuilders or competitive athletes.
After ten weeks, the men gained around seven pounds of muscle. And that’s without doing any training.
A similar group of men who trained with weights three times a week, but who didn’t get the injections, gained a little over four pounds.
Think about that for a second.
Taking testosterone and doing nothing produced a faster rate of muscle growth than going to the gym three times a week.
It was the guys combining strength training and testosterone injections who saw the best results. On average, they gained over a pound of lean tissue each week, ending the study with an additional 13 pounds of muscle mass added to their frame.
In other words, the men who lifted weights and took testosterone gained muscle three times faster than those who lifted weights without any pharmaceutical assistance.
In hormone replacement therapy terms, 600 milligrams of testosterone per week is a lot, around six times higher than the dose usually given to men with low testosterone levels.
But it’s a drop in the bucket compared to what some people are using. A study that looked at the doping practices of strength athletes and bodybuilders found that one guy was on a whopping 2000 milligrams of testosterone per week .
And that was just the tip of the iceberg. He was also taking various other compounds, including deca-durabolin (600–800 milligrams per week), dianabol (50 milligrams per day), insulin (12 IU per day) and ephedrine (60 milligrams per day).
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 hand-wringing do-gooders out there telling you how to 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.
The length of time it takes for a muscle to grow is also affected by whether you’re building that muscle from scratch, or re-building muscle that’s been lost.
Re-building muscle that you’ve had in the past, but subsequently lost, happens more quickly than gaining it in the first place. That’s because of a phenomenon known as muscle memory.
When a muscle is gained, lost and then gained back again, it will grow more quickly during the re-building phase compared to the initial training period from an untrained state .
Muscle tissue itself can’t actually “remember” anything. Rather, the number of nuclei in muscle cells increases when you lift weights. But those nuclei aren’t lost when you stop training and your muscles shrink. Instead, the extra nuclei form a type of muscle memory that allows the muscle to bounce back quickly when you start training again.
All other things being equal, if you’ve been in shape before, your muscles will grow a lot faster than 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 are real or not, this is a short (68 seconds) video clip that’s worth watching.
It’s taken from a documentary called Bigger, Stronger, Faster, which is well worth a look if you haven’t seen it already.
Even though it’s old news to anyone who’s seen what really goes on in the fitness industry, a lot of people are surprised when they realize that this kind of thing actually happens.
The Limits of Human Muscle Growth
There are genetic factors outside your control that affect how long it takes to 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.
You’re not going to gain 30 pounds of muscle in less than a month. It doesn’t matter how many supplements you’re using, what special foods you’re eating or how much training you’re doing. It’s not going to happen.
Even Arnold Schwarzenegger, who combined great genetics and a Herculean work ethic with more than 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), there’s no way that a drug-free, genetically average guy can expect to do the same thing in a fraction of the time.
Building shirt-straining muscle takes a long time. Most people will need to train for somewhere between 3 and 5 years before they get anywhere close to their physical limits as far as muscle size is concerned.
That’s 3-5 years of hard work, proper training and good nutrition. It’s not something you can do in 30 days, 12 weeks or even 12 months.
However, that’s not to say you won’t see improvements relatively quickly, providing your diet and training program are set up properly.
In fact, the process of building muscle begins almost immediately after your first workout .
Just three hours after training, muscle protein synthesis is already ramped up. Your body is busy repairing damaged muscle fibers, as well as laying down the new muscle protein that makes each fiber bigger than it was before .
To give you an idea of the time course of changes in muscle thickness over time, check out the figure below.
It comes from a team of Japanese researchers, who took a group of untrained men, and got them to do nothing but the bench press three times a week for six months . Every week, they used ultrasound scans to assess changes in muscle thickness in the chest, triceps and biceps.
As you can see, there was a small increase in muscle size from week to week. Those gains were small, and flattened out over time. But the pecs and triceps were still growing on a regular basis.
Don’t be discouraged if progress seems slow. It takes a while for short-term changes in protein synthesis to show up as actual changes in muscle mass, and you may not notice those changes for several weeks or even months.
How Long Does It Take to Build Muscle?
So, let me put all the theory to one side and answer the question:
How long does it take to build muscle… really?
Let’s assume that all the muscle-building stars are aligned. By that, I mean that you’re new to lifting weights, training hard 3-5 days a week, eating enough food and getting all the protein your muscles need to recover and grow.
You’re also in your twenties with all the hormonal advantages that go with it, a relatively low-stress lifestyle, and getting 8-9 hours of sound, restful sleep each night. You have the discipline to eat right and train hard on a consistent basis, week in and week out, for months at a time.
Under those optimal conditions, it’ll take the average guy 3-4 months to gain 10 pounds of muscle.
Keep in mind that results will vary from person to person. Some folks, despite training hard and eating right, will gain closer to 3 or 4 pounds over the same period of time.
Others will make faster gains. In one study there were a few individuals who saw stand-out results, adding around 15 pounds (6.8 kilograms) of muscle in 12 weeks . In another, a group of untrained beginners gained, on average, 12 pounds (5.6 kilograms) of muscle after 10 weeks of weight training .
What if conditions are less than optimal? What if you’re in your forties, short on sleep and your diet isn’t all that it could be?
If so, the results will come more slowly, and you’ll need to scale back your expectations accordingly.
No matter how fast you gain muscle, it won’t be too long before the law of diminishing returns kicks in. Everything happens quickly when you’re just starting out. But you won’t keep building muscle at the same rate indefinitely, and your results are going to slow down over time.
In other words, the first 10 pounds of muscle might come in four months or less. The next 10 pounds might take eight months. Adding another ten pounds might happen a lot more slowly, over a period of maybe 2-3 years.
That’s because there is a “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.
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.
However, those gains aren’t going to come at a steady pace throughout the year. Most of your progress will be made in the first 3-6 months, and slow down over time.
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 new muscle.
You can certainly gain weight at a faster rate, as the addition of fat and water weight will add a few more pounds (maybe a lot more depending on how relaxed you are with your diet). But if it’s just muscle growth you’re talking about, those numbers are roughly where the natural limits lie.
SEE ALSO: THE MUSCLE BUILDING CHEAT SHEET
If you're fed up spending hours in the gym with nothing to show for it, then check out The Muscle Building Cheat Sheet.
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