No matter whether you’re trying to bulk up or get shredded, you’ve likely wondered how long it actually takes to build muscle.

The fact of the matter is that the muscle-building process is unique for all of us and while it can be easy to become discouraged when you don’t notice results right away, it’s important to remember that building muscle ultimately takes time.

In order to address some of the most common questions and concerns surrounding the muscle-building process, we’re going over how your muscles actually grow, how long it may take, as well as factors that can affect your muscle-building potential.

How do muscles grow?

Muscles grow through a process known as hypertrophy, which is the main way your body repairs and rebuilds damaged muscle tissue. On a microscopic level, your muscles are made up of fibers, which in turn are made up of proteins. Stimuli like resistance training can overload your muscles, causing some of these proteins to break down.

After you lift weights, a chain of events known as muscle protein synthesis is set off in your body to repair and rebuild damaged muscle fibers — your body is constantly shifting between states of muscle protein breakdown and synthesis.

So when do your muscles actually grow? They grow when the amount of protein synthesized in your muscles exceeds the amount that’s broken down.

How long does it take to build muscle?

Following a single training session, protein synthesis is increased in the muscle for 24 to 48 hours. But one training session is not enough to pack on muscle mass. In order to build muscle, you need to put your body in a position where it’s consistently in an elevated state of muscle protein synthesis.

The combination of a consistent diet and a steady training routine is ultimately what leads to gains in size and strength over time. Additionally, proper supplementation can also be an effective means of stimulating muscle protein synthesis immediately after training.

Building muscle is not an immediate process though. There may be some improvements on a microscopic level following a single training session, but directly observable results take time.

Although you were probably hoping for a short and simple answer, there are a number of factors such as genetics, age, gender, and training experience that will affect how long it takes any given individual to build lean muscle mass.

how long to build muscle

What factors affect How Long It takes to build muscle?

There are numerous things to consider when you’re trying to figure out how long it actually takes for you to build muscle. Let’s take a look at some of the different factors that will affect the rate at which you are able to pack on size and strength.


Genetics can play a role in how quickly you are able to pack on muscle. While some people are extremely reactive to exercise-induced stimulation, others may not be.

A 2005 study recruited 585 adult subjects (342 women, 243 men) and put them through a 12-week resistance training program. The researchers found a wide variation in the amount of size and strength gains made by both men and women in the study.

Some subjects made little to no gains (one subject even had a 2% loss of muscle mass), while others made substantial improvements — one individual saw a 59% increase in muscle mass and another doubled their strength.

Most people in the study fell somewhere in between these two extremes, making modest improvements in muscle size and strength. About 40% of the subjects increased their muscle mass by around 15%.


For the average person, 12 to 16 weeks seems to be enough time to see some modest increases in muscle size and strength.


Age also plays a sizable part in our ability to build and maintain lean muscle mass.

As we grow older, we become increasingly prone to muscle protein breakdown. This can result in a decrease in muscle mass and can negatively impact our quality of life.

However, older individuals are still plenty capable of experiencing positive adaptations to weight training.

A study published in 2011 compared the effect of a 16-week training program on 2 groups of participants. One group consisted of individuals between 20 and 35 years of age. The second group was people between the ages of 60 and 75.

Coming into the study, the older group on average had lower percentages of lean muscle mass compared to the younger group. After 16 weeks of training, however, the older group was able to achieve similar levels of muscle mass compared to the younger group at baseline.

Researchers have also found that younger individuals on average, respond better to resistance training than older people.


While younger people are generally able to build more muscle in the same time period, older individuals have been shown to achieve measurable gains in muscle mass within 4 months.


Exercise scientists have long investigated the role of sex in muscle development. Research findings show that on average, females are able to gain more strength over the same time period in comparison to males. However, it’s a different story when it comes to increases in muscle size.

Exercise scientists have found that on average, males are able to develop more muscle in a shorter time frame in comparison to females. This is at least partially due to higher levels of testosterone in males.

More specifically, the muscles in the upper body tend to develops more quickly in males than females. For instance, A 2005 study compared the developments in arm size and strength in male and female participants over the course of a 12-week program. On average, the males made increases of about 20%, while the females were closer to 18% over the same time period.


16 weeks of training seems to be enough time for both the average man and woman to experience modest gains in muscle mass.

⫸Training Experience

Training experience is another factor that can dramatically impact the time frame in which you’re able to build muscle.

Individuals with little to no training experience will likely find it easier to build muscle in comparison to those with extensive training backgrounds.

The muscles in untrained individuals are far less accustomed to the stresses placed on them by resistance training. Ultimately, this leads to more protein breakdown in the muscle tissue, which in turn leads to more hypertrophic gains with the right diet.

For instance, a study published in 2003 examined muscle adaptations in a population of young men with no previous training experience. The study found that on average, subjects saw increases in muscle size after as little as 3 weeks of training.

As you continue to log more hours in the gym, however, your muscles become increasingly accustomed to the stresses placed on them by your exercise routine. This leads to less tissue damage, which, in turn, leads to less hypertrophy.

In other words, what this means is that increasing lean muscle mass becomes more difficult as training experience goes up.

At the end of the day, individuals who have been training for a long time may only experience a few percentage points of improvement in lean muscle mass over the course of a year.


Packing on lean muscle mass is a substantially quicker process for individuals who have little to no training experience. An average person may be able to make some noticeable gains in muscle size and strength in as little as a month.However, as your experience in the gym grows, it will take longer and longer to increase lean muscle mass.

How to maximize your muscle-building potential

outside workout

When it comes to building muscle, there are a number of factors that are out of your control. But don’t fear! Exercise selection and programing also play important roles in the muscle-building process.

So, what should you be focusing on in your routine if you’re looking to maximize your muscle-building potential?

1. Intensity, reps, and sets

Researchers have found that high-resistance exercises are more effective for inducing muscle growth when compared to low-resistance training approaches.

Working at intensities at or above 60% of your one-rep max is the ideal range for building muscle. Each exercise should include multiple sets and a range of 6-12 reps for optimal muscle gains.

2. Rest intervals

In order to maximize the amount of muscle you’re able to build, make sure that your rest intervals are not too short. For instance, if you only wait 30 seconds between sets, you may not have enough time to regain your muscle strength, which can ultimately reduce your performance in subsequent sets.

On the other hand, you should also ensure that your rest intervals aren’t too long either. A couple of minutes between sets may allow you to regain strength, but the amount of metabolic stress on your muscles will also be greatly reduced — less metabolic stress means less hypertrophy.

The simple solution is to meet in the middle. A rest interval of 45 to 60 seconds between sets seems to be the optimal range for maximal muscle growth.

3. Rep speed/tempo

The speed (AKA tempo) at which you perform your sets also plays a role in your ability to build muscle. A resistance-based exercise consists of two basic motions: the concentric and eccentric portions of the movement.

Take the bench press, for example, the concentric part of the movement is when you’re pushing the bar away from the chest. The eccentric part is when you’re lowering the bar towards it.

Research shows that performing the eccentric portion of the exercise at a slower speed puts the muscle under tension for an increased period of time. This, in turn, places a greater strain on the muscle, resulting in the breakdown of more muscle proteins.

To really maximize your gains, try to go for an eccentric that lasts for about 4 seconds.

4. Training to failure

Training to failure refers to the practice of performing as many reps as you can until your muscles aren’t able to perform anymore and it’s another variable that can affect your muscle-building potential.

Training to failure on every set of every exercise, however, is not recommended. In addition to increasing your recovery time post-workout, it can also drastically increases your potential for getting injured.

Alternating in your training sessions between sets that go to failure, and sets that don’t can minimize the risk of overtraining and maximize your gains.

5. Use high-performance supplements

Using the proper supplements can also help to improve the capacity of your muscles to grow. High-performing supplements like whey protein and Muscle Performance Optimizer can help to improve muscle recovery, stimulate muscle protein synthesis, and improve the overall quality of your workout.

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6. Get sufficient sleep

When you sleep, your body balances it’s hormone levels. Failing to get sufficient sleep ultimately doesn’t allow your body to balance itself out, which can make it much more difficult to pack on size and strength.

In order to maximize your muscle-building potential, aim for somewhere between 7-9 hours of sleep each night.

7. Rest your muscles

Following a bout of resistance training, it’s crucial that the affected muscles have at least 1 to 2 days of rest. Overworking your muscles can have a negative impact on your ability to build size and strength. On top of that, it can also increase your risk of injury.

Wrap up

The muscle-building process is different for everyone and it’s important to understand the factors that affect how long it takes, including both those that you can control and those that you can’t.

For the average person, somewhere between 12 – 16 weeks of training appears to be enough time to see modest gains in size and strength, although it may take longer for well-trained individuals. No matter where you are in your fitness journey, properly managing your diet and training program is the best way to maximize your muscle-building potential.