How Fast Can You Build Muscle?

As soon as you’re setting down the weights after your first set in the gym, your muscles starts sending signals for growth. And an hour or two later, when you are done with your workout, the process of building new muscle protein is already in full swing.

But how fast can you really build muscle? And how long until they’ve grown enough to be noticed by you and those around you?

These questions, I will try to answer in this post.

How Much Muscle Can You Build in 2–3 Months?

Let’s cut straight to the chase. Below, you can see some typical results in terms of muscle growth, in training studies lasting 2–3 months.


  • 5–15% muscle thickness
  • 10–30% muscle area
  • 2–3 kg fat-free mass


  • 3–10% muscle thickness
  • 6–20% muscle area
  • 1–2 kg fat-free mass

Sources.1 2 3 4 5

Fat-free mass is, just as it sounds like, anything in your body that isn’t fat. That means muscles, bones, organs, water, glycogen, the contents of your stomach and intestines, and so on. It is easier to measure fat-free mass in a body than only the pure muscle mass, and that’s why it’s so frequently used in training studies.

Generally, muscle mass constitutes about half of your fat-free mass.6 But when it comes to increases in fat-free mass as a result of training, then the majority of that added fat-free mass will likely be muscle, followed by glycogen.

Building muscle as a beginner
How fast can you expect your guns to grow?

Your Muscles Grow Fastest in the Beginning

Assuming that you train effectively from the start, and eat and sleep well, then you can expect your muscles to grow fastest in the beginning of your training career, and then slower and slower as your muscles become more accustomed to the training.

A Japanese study provides us with a good example of this. Seven, previously untrained, young men trained bench press three times a week for 24 weeks, doing 3 sets x 10 repetitions until failure every workout.7 The diagram below shows how their chest and tricep muscle thickness increased during the just over five months of training.

Muscle growth in half a year

These seven young men increased the thickness of the pecs by 43%, on average, in just under half a year of training, and the thicknesss of their triceps with 17%. The triceps probably grew less than the pecs, because bench pressing isn’t enough for full tricep growth.

Anyhow, by looking at the graphs, one can discern that the rate of muscle growth seems to decrease as the months go by.

… And One Day You Will Reach Your Peak

It will probably require more than a decade of hard training before your reach that point, but you should know that your muscles won’t grow for all infinity.

One example of that comes from a study on highly competitive (and drug using) bodybuilders at an elite level, who during 24 weeks of training failed to build any significant amount of muscle mass at all.8

Thus, at some point, your training will shift to become more about fine-tuning details in your physique, or retaining the (by this point, probably pretty big) muscle mass you’ve acquired.

However, most of us have many more years of fine muscle growth to look forward to, and it is well worth to consider how you might maximize your muscle growth along the way.

This Affects How Fast You Can Build Muscle

How fast your muscles grow depends on several factors, such as your …

  • Training program
  • Training status
  • Age
  • Genes
  • Diet
  • Sleep
  • Other stress

Even if you and another person would follow the same training program, you could get wildly different results, since so many factors are at play.

One such factor that you cannot influence yourself, is your genes. In one study, it was found that the persons that responded most favorably to the resistance training (so-called “high-responders”) built upwards of four times more muscle mass than the ones who responded least favorably (“low-responders”) did during the 12 weeks of training.9

Fast vs slow muscle growth

The only thing you can do, is to do the best with what you’ve got, and pay attention to the factors that you can affect, such as good training, diet and sleep, and then hope that it will be enough to get good results from your efforts.

An encouraging fact in this matter is that different people seem to respond to different types of training.10 If you experience that your current training regimen doesn’t really seem to give you the results you would expect, despite your best efforts regarding diet and sleep, then it might be well worth to try a different training strategy. Maybe a shift of training volume, training frequency, or load and number of reps might lead to new growth?

Large Variations in Rate of Muscle Gain

There is plenty of evidence that we build muscle at different speeds. Another such piece of evidence is the result of a massive training study, featuring a whopping 585 participants. The participants were previously untrained, young adults, and they trained their biceps twice a week for 12 weeks.11

The average gain in bicep muscle area was 15–20% in men and women alike, but the spread was such that some participants decreased their muscle area by 5%, while some increased it by a crazy 55%.

Biceps muscle growth rate

More Examples of Quick Muscle Growth

You’ll generally see the quickest muscle growth in young, previously untrained persons that start following an ambitious and well-planned whole-body training routine, while at the same time eating a slight caloric surplus and covering their protein requirements.

We find two examples of very rapid muscle growth in a study, where 56 young, previously untrained men trained five times a week, following a rotating push/pull/legs routine, for 12 weeks. Immediately after each workout, the participants drank 18 grams of protein from either skim milk (0.1% fat) or a soy protein shake. One hour later, they drank one more of the same sort. After 12 weeks of this regimen, the participants had increased their fat-free mass by 3–4 kg. However, the results of two participants stood out from the rest: they had gained 7.5 and 7.0 kg of fat-free mass, respectively. Truly an astounding result after only twelve weeks of training!12

Fast muscle growth from soy and milk protein
After 12 weeks of training, 5 times a week, on a rotating push/pull/legs split, almost all participants had increased their fat-free mass. The two guys that had grown the most, increased their fat-free mass by 7.0 and 7.5 kg, respectively.

An interesting result for those of you who still doubts that it is impossible to build muscle and lose fat at the same time, is that as the participants gained 3–4 kg of lean mass, they also lost half a kilo of fat. In fact, the group that received skim milk not only increased their lean mass the most (with 4 kg on average), they also lost the most fat simultaneously: almost 1 kg on average.

In another study, lasting 10 weeks, 19 untrained young men trained four times a week: two upper/lower body workouts. Every day, they ingested two shakes of either 20 g of carbohydrates (dextrose) or 20 g of protein, for 40 g of either carbohydrates or protein in total. They drank this on both rest days and training days, and on the training days they took one shake before training and one after.13

After 10 weeks, the group that had received 40 g of extra protein per day, had gained 5.6 kg of lean mass on average, while simultaneously losing 1.1 kg of fat mass.

Muscle growth after 10 weeks

So, what’s the matter if you don’t gain as quickly as the participants in the example studies above did? Sure, genetics might be a factor. But it is more productive and satisfying to focus on what you actually can influence yourself. Do you really train as hard as you know you could? Do you really eat and sleep well enough to support good training results, or can you improve those parts? If you want your results to surpass the ordinary, so must your actions do.

Read more: Protein Intake: How Much Protein Should You Eat per Day?

How Long Before You See Results of Your Training?

Kilos here and percentages there – how long will it take before you actually notice any gains from your training?

Your muscles are covered beneath a layer of fat. How much fat you have, will affect how long it takes before your muscle gains are visible through it. Typically, it is possible to notice muscle growth after a month or two of good training, in normal-weight persons that starts lifting weights.

How Much Muscle Can You Build in a Year?

As previously stated, it is not uncommon for a beginner to increase his or her fat-free mass with 2–3 kg in the first few months of training. A person that is already accustomed to training could gain 1–2 kg in the same period if the training program and other circumstances are good.

Related: Barbell Training Program for the Beginner

You will be making your biggest gains at the beginning of your training career, but also if you move from a stale training program which you’ve plateaued at, to a new, stimulating routine. It will however be difficult to maintain a high growth rate over long time frames, such as a year.

Considering this decrease in marginal gains, an estimate is that over the course of a good training year, you can build approximately twice the fat-free mass mentioned in the paragraph above: 4–6 kg in a year for a beginner, and 2–4 kg for a more experienced lifter.

It requires, however, that your training is both sufficiently hard and effective.

Woman training deadlifts

Fast Muscle Growth Requires Stimulating Training

When you kick off a new training cycle and your training motivation soars high, you might see great progress during the first month or so. But after a while, it is very common that your training becomes routine, and you are no longer challenging yourself during your workouts, for example by really trying to increase your training weights.

In training studies, the participants are often supervised by the researchers or hired trainers while working out. These supervisors are standing next to the participants, cheering them on and encouraging them to give each set their best effort. As soon as the participant successfully completes the designated number of reps for a given set, the weight is increased for the next workout.

This means that the workouts often are quite hard and strenuous, which might explain why even persons that have trained for many years suddenly can see good muscle growth when they participate in a study.

To do this on your own, without trainers pushing you, requires much more focus and determination than just going to the gym and yawning yourself through your workout. However, if you are able to push yourself to a higher degree, then your reward in terms of gains might be well worth the effort.

If your goal is to sustain a fast muscle growth for as long as possible, then it is imperative that you keep a close eye on your training in one way or another, to make sure that you are lifting heavier or more over time. One way to do that is, of course, to use our app StrengthLog to log your workouts, and making sure that you are lifting a little more each session, week, or month. If your workouts are starting to feel so comfortable that you can just coast comfortably through them, that might be your sign that it is time to push the gas pedal down a bit again.

Optimize your training for muscle growth
”Plan before hunting, discuss after hunting, hunt while hunting.” Effective strength training requires you to continually switch between planning, execution, and evaluation. For the best possible results, that will be an ongoing process throughout your training career.


  • How fast you will be able to build muscle depends on several factors, such as your training program, training experience, age, genetics, diet, sleep, and other stress.
  • It is common to see noticeable gains in muscle mass after only a month or two of effective training.
  • As a beginner, you can expect to increase your fat-free mass with 2–3 kg during your first few months of effective training. You who already are at a higher training status might be able to gain 1–2 kg in a few months of good training.
  • Corresponding increases in muscle area of the trained muscles might be 10–30% in a few months for the beginner, and 6–20% for the more experienced lifter.
  • In a year, it is not uncommon for a beginner to increase his or her fat-free mass with 4–6 kg, and if you’ve trained for a couple of years already, you might gain around 2–4 kg.
  • If you’ve trained hard and effectively for a long time, say, a decade or more, then you will have to play all your cards right to be able to gain at all.

More Reading:


  1. BioMed Research International. Volume 2013, Article ID 643575. Highlights from the Functional Single Nucleotide Polymorphisms Associated with Human Muscle Size and Strength or FAMuSS Study.
  2. Age (Dordr). 2016 Feb;38(1):10. doi: 10.1007/s11357-015-9870-1. Epub 2016 Jan 15. Heterogeneity in resistance training-induced muscle strength and mass responses in men and women of different ages.
  3. Br J Sports Med. 2018 Mar;52(6):376-384. doi: 10.1136/bjsports-2017-097608. Epub 2017 Jul 11. A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults.
  4. Muscle Nerve. 2017 Dec;56(6):1022-1030. doi: 10.1002/mus.25696. Epub 2017 Jun 11. Muscle growth: To infinity and beyond?
  5. Physiol Rep. 2015 Aug;3(8). pii: e12472. doi: 10.14814/phy2.12472. The effect of training volume and intensity on improvements in muscular strength and size in resistance-trained men.
  6. Am J Hum Biol. 2018 May;30(3):e23102. doi: 10.1002/ajhb.23102. Epub 2018 Jan 22. Skeletal muscle mass in human athletes: What is the upper limit?
  7. Interv Med Appl Sci. 2012 Dec; 4(4): 217–220. Time course for arm and chest muscle thickness changes following bench press training.
  8. J Appl Physiol (1985). 1992 Apr;72(4):1512-21. Effects of resistance training on elbow flexors of highly competitive bodybuilders.
  9. J Appl Physiol (1985). 2011 Feb;110(2):309-17. High Responders to Resistance Exercise Training Demonstrate Differential Regulation of Skeletal Muscle microRNA Expression.
  10. Biol Sport. 2016 Jun; 33(2): 117–126. A genetic-based algorithm for personalized resistance training.
  11. Med Sci Sports Exerc. 2005 Jun;37(6):964-72. Variability in muscle size and strength gain after unilateral resistance training.
  12. The American Journal of Clinical Nutrition, Volume 86, Issue 2, August 2007, Pages 373–381. Consumption of fat-free fluid milk after resistance exercise promotes greater lean mass accretion than does consumption of soy or carbohydrate in young, novice, male weightlifters.
  13. Willoughby DS, et al. Amino Acids. 2007. Effects of resistance training and protein plus amino acid supplementation on muscle anabolism, mass, and strength.
Photo of author

Daniel Richter

Daniel has a decade of experience in powerlifting, is a certified personal trainer, and has a Master of Science degree in engineering. Besides competing in powerlifting himself, he coaches both beginners and international-level lifters. Daniel regularly shares tips about strength training on Instagram, and you can follow him here.