The most common way people find Beyond Macros is by searching “mass gain for CrossFit”.  Today’s video is going to cover what it takes to put on muscle while doing CrossFit.

I’ll also answer the other question I frequently get which is, “can I put on muscle just doing CrossFit?”


 Understanding Muscle Gain

I’ll get to the 3 keys to gaining muscle when you do CrossFit in about two minutes. Before we do, we need to lay a foundation of understanding about muscle gain.

First things first, let’s establish this: your body doesn’t want to gain muscle if it doesn’t have to.

Gaining muscle is expensive. It’s not just in terms of your grocery bill.

It costs your body a lot of energy to build and maintain muscle. Muscle uses a lot of energy, even when you’re sitting down watching YouTube or listening to a podcast in the commute to your local box.

Muscle Is A Liability

In my opinion, your survival-minded body probably sees muscle as a liability. Why? In times when food is scarce, that energy hungry muscle becomes a survival risk. Compared to fat, your body really can’t get that much energy from breaking down it’s storage of muscle.

Your body will, however, want to put on muscle if it has a good reason from a survival perspective. 

So what would that good reason be?

It has nothing to do with your deep why, or the fact that you were a skinny, insecure adolescent and teen like me.

And that reason is probably twofold.

To find food and attract a mate more effectively.

As for attracting a mate

It’s well established that neither males nor females, on average, prefer partners with loads of muscle mass.  This is actually the preferred body composition based on one study

As for finding food

If you ask your body to perform a physical task, let’s say running down a gazelle in a long hunt, and this stresses your body- then your body will adapt to become better at that task because it directly impacts your survival.

In this case, you are more likely to see adaptations in your ability to move over a long distance. And more muscle won’t benefit that goal after a certain point. Unless you’re a bulk pony like Hunter McIntyre.

If the task that stresses your body requires you to be stronger or have more muscle mass, then you will put on muscle mass if you feed it properly.

If you need to be strong enough to lift a log over your head to construct a shelter for yourself and your family, and that stresses your body- then your body might adapt to become better at the task because it directly impacts your survival.

Marathon Runners vs Strongmen

You might be thinking, “duh, Matt. Look at marathon runners vs. strongmen. Of course we need to lift heavy things to gain muscle”

Additionally, you might be thinking that answers the question “does crossfit help you gain muscle” because most days you lift heavy at the beginning of class before doing your conditioning.

But just like the runner whose body only puts on enough muscle to perform the task of running efficiently, your body will adapt in the same way with CrossFit classes.

When you’re a newbie to any form of resistance-based training, CrossFit included, you will put on muscle. No doubt.

Over the past decade, one phenomenon I’ve observed training and coaching at multiple CrossFit gyms: long-term members who just show up to group class and do nothing else hit a body composition plateau in the first year and stay there.

It takes doing some hypertrophy or strength-focused training outside of CrossFit. Plus, a nutrition plan that supports the additional workload to push their bodies PAST that plateau and towards a more muscular physique.

This makes sense when we look at the evidence about what drives muscle gain in training. 

The Evidence

The evidence is always evolving, but there are three mechanisms that are generally accepted reasons why you will adapt to a training program and gain muscle.

  1. Mechanical tension
  2. Metabolic stress
  3. Muscle damage


Let’s discuss each:

Mechanical Tension

Mechanical tension refers to the loading of muscle. Both the force production and the stretch phases of loading are believed to increase muscle mass. Mechanical tension alone can induce hypertrophy. However, even programs with high mechanical tension might not increase muscle mass, and instead might make the nervous system more efficient at recruiting muscle fibers you already have.

I found the research into mechanisms of hypertrophy fascinating because there is a Japanese style of training called Kaatsu, which is a blood flow restricted training. Kaatsu uses very low mechanical tension. Only about 20% of 1RM, yet produces muscle hypertrophy.

Research into Kaatsu training provides some great insights into the potential mechanisms that can explain why metabolic stress induces muscle hypertrophy.

Metabolic Stress

Metabolic stress involves the accumulation of metabolic by-products, such as blood lactate, inorganic phosphorus, and hydrogen ions. Think about that wall you hit at the 90 second mark in Fran. You’re feeling those metabolic byproducts in action. They’re created at a faster rate than your body can buffer them.

It is believed that these matobilites caused by stress stimulate muscle growth in a number of ways.  These mechanisms include:

  • muscle fiber recruitment,
  • anabolic hormone release,
  • myokine activation or deactivation,
  • production of free radicals, and
  • cellular swelling

It appears muscle fiber recruitment is one of the largest contributing factors. As metabolites like hydrogen ions build up and a muscle group fatigues, more fast twitch fibers are recruited to continue moving the load.

Another proposed reason that metabolic stress can induce hypertrophy is that your body will release anabolic hormones in response to metabolites of glycolysis. It is also believed that this also creates the anabolic environment after a workout. 

The research on how myokine alteration, reactive oxygen species production, and cell swelling affect hypertrophy seem less clear in my research with a number of conflicting findings.

Muscle Damage

The final factor we have is muscle damage.  When muscles tissue is damaged from the stress of exercise, the muscle tissue signals the body’s repair mechanisms to come in and clean out debris, maintain the structure of the tissues, and stimulate growth factors.

In terms of these 3 mechanisms, Brad Schoenfeld and colleagues suggested some practical applications of this knowledge in a 2010 paper. This seemed to show that programs promoting high metabolic stress and moderate mechanical tension are the best for promoting muscle hypertrophy.

But of course, there is way more that goes into program design, and research has advanced in the decade since that paper was published.

Key Factors Creating Hypertrophy-Focused

The key factors that evidence-based coaches will manipulate to create a hypetrophy-focused program for their clients include:

  • Training volume
  • Load- so the weight being lifted.
  • Training frequency- usually sessions per week
  • Training to momentary muscular failure- so hitting a single set maximum
  • Exercise variation- not only choosing different exercise types, but also movements in different planes and at different angles
  • Contraction type – concentric and eccentric
  • Exercise order – the order in which the exercises are performed in a single session
  • Repetition tempo – meaning how long are your concentric movements, and how long are your eccentric movements
  • Interset recovery which is the time you rest in between sets.

A more recent review concluded that loading doesn’t seem to matter as hypertrophy can be achieved at a wide range of loads as long as the intensity and training volume are controlled. This is evident when you look at Kaatsu training which employs very light loads of about 20% 1RM while restricting blood flow.

I will throw out that another paper compared training at 20, 40, 60 and 80% of 1RM, and there didn’t seem to be a difference between 40, 60, and 80% in terms of muscle hypertrophy whereas there was significantly less hypertrophy at 20% of 1RM.

The training factors that do seem to play a major role in whether or not you gain muscle are training volume, training frequency relative to training load and your experience level.

The other factors I listed earlier are all important, but as with any program it is important to consider the context of your goals, training experience, and other activities.


Does CrossFit training alone provide the necessary conditions for muscle gain?

Specifically, does it provide high metabolic stress and moderate mechanical tension?

Here’s my opinion based on experience and no evidence from controlled studies.

I’d venture to say yes, yes it does. There is both metabolic stress and moderate loading in most CrossFit programs.

Yet, There Are Too Many Variables

Since CrossFit is constantly varied in nature and every gym programs differently — it’s impossible to make a broad generalization here about whether CrossFit promotes muscle gain. Plus, if you go to a class and complete the workout at a low intensity, the metabolic stress may not be there.

Another important consideration is that as you get experienced with a movement you become more efficient and will experience less stress.

Even though exercise selection in CrossFit is varied and there are hundreds of options, group classes run into problems with equipment availability and programming can be unconsciously biased towards particular movements at the same loads. And you might adapt to become really efficient at swinging that 24kg kettlebell and doing burpees.

CrossFit also has novel exercise selection, I’d argue it’s biased towards saggital plane movement. Pretty much moving things up and down. 

Training volume for some muscle groups may be high, but the problem with CrossFit classes is that you might go on the days it’s convenient for you. So you may have a low training frequency for certain muscle groups. 

Ultimately, there are too many uncontrolled factors with CrossFit, and if your goal is to gain muscle, CrossFit can certainly help, but I dare say group class is not the optimal path to getting jacked.

My Path To Glory

When I was the most jacked and juicy is when I was training to compete at CrossFit Regionals. My program had lots of structure related to Olympic Weightlifting and power-lifting. We had focused bodybuilding sessions, and there was conditioning layered on top.

When I look at the top CrossFit athletes, I see physiques that look muscular and better than most natty bodybuilders. But I know those athletes didn’t get that way with 20-minutes of strength work followed by a 10 minute metcon.

Their programming is periodized. 

After regionals every year, my coaches would program strength and hypertrophy cycles. We’d get strong and big as a focus. 

Then as the Open approached, we’d layer in more conditioning. 

This is why we looked the way we did.

What To Do To Gain Muscle Mass In Crossfit

So what should you do if your goal is to add muscle as someone who generally goes to CrossFit classes?

Two things.

  • First, you should have a coach write you a hypertrophy-focused assistance program that you can do outside of class.

If you’re newer to lifting, you can probably get away with just two additional sessions each week- and it might only take you 30 minutes each session.

If you’re more experienced, you might need 3 additional hypertrophy sessions on top of group class.

In a perfect world, you have an expert evidence-based programmer at your gym who can make sure your assistance work program doesn’t interfere with the movements at your CrossFit classes. If that’s not possible, just find an expert evidence based programmer.

  • Second, you need to eat a calorie surplus.

I say this second because we’ve had some clients sign up for our coaching with a muscle gain goal, but they don’t want to do anything except group class, and they don’t want to gain any fat.

Eating a Calorie Surplus Doesn’t Automatically Lead to Muscle Gain

Unfortunately, eating a calorie surplus doesn’t automatically lead to muscle gain. If it did, every obese person on earth would look like the Rock underneath a layer of fat. A calorie surplus itself is more likely to lead to fat gain if you’re not giving your body a reason to put on more muscle mass.

Remember the discussion earlier about how muscle is a liability from a survival perspective? If there is no reason for it, whereas fat is an asset in case you can’t find food for a long time?

Even though you’re not sedentary, and you are doing CrossFit, you will gain some fat on a calorie surplus. 

It’s just facts. A true calorie surplus vs. a calculated calorie surplus means your body is going to have to do something with that excess energy. Some might go to muscle building, but some is also going towards storing the energy as fat.

Only extreme newbies or people recovering from injury who we put on a calculated surplus also lose fat or don’t gain fat with their muscle gain.

Anybody with experience will put fat while eating a calorie surplus, with few exceptions.

So to MAXIMIZE your muscle gain on a surplus, you do FIRST have to follow a hypertrophy focused program in addition to your CrossFit training.

My Recommendations:

But when it comes to gaining mass with CrossFit as your primary training, I usually recommend a smaller deficit than I would if working with a client who just wanted to pack on as much muscle as possible regardless of the consequences.

Firstly, because CrossFit training uses a lot of bodyweight kipping, rebounding on box jumps, etc. And this can be taxing on connective tissues.

Your connective tissues don’t adapt as fast as your muscle, and I believe the extra weight you’ll be carrying and extra strength you’ll gain puts you at higher risk of connective tissue injury.

I believe the best way to combat this is to add 15g of collagen per day to your supplement routine during mass gain to support joint health, and to do your best to keep your gains lean.

To keep your gains lean, I recommend aiming for about a 10-15% calorie surplus and adjusting your nutrition to keep weight gain under 1lb per week on average.

For protein intake, you could set it at about about 1g/lb of bodyweight, but protein overfeeding studies seem to show that surplus calories from protein seem to benefit lean tissue with no fat mass gained. So if you can stomach it, you can push your protein numbers up.

But those are just the nutrition and training factors to consider.


We’re called Beyond Macros for a reason. We believe a transformation goes beyond nutrition and exercise.

When it comes to making a lean muscle gain transformation, controlling sleep and stress are two important factors.

One former client, Kyle, added 3.8lbs of muscle while losing 7lbs of fat. And Kyle was no inexperienced n00b.

Here’s what he did right that led to the coveted lose fat, gain muscle transformation:

  1. He was eating the right balance of macros working with a coach.
  2. He was following a hypertrophy focused program after a long stint of just doing CrossFit.
  3. He was on paternity leave from work which meant lower-than-normal stress levels.
  4. Despite a newborn, his sleep tracker was showing better than usual sleep data.

Again, Kyle’s gains were unusual. We have helped a number of people gain muscle and lose fat at the same time but it is far less common considering he was an intermediate lifter already.

Expectations on Muscle Gain

So here’s what to expect in terms of muscle gain if you do everything right, depending on your experience level. 

You will see diminishing returns with muscle gain. They are never linear, and experienced lifters KILL THEMSELVES for the smallest gains in muscle mass. This is why I have so much respect for natural athletes who manage to max out their genetic potential.  

Intermediate lifters below their genetic potential might see up to 1lb of (450g) muscle gain per month. Or about 0.25-0.5% of total body weight in muscle gain per month.

Athletes at about their genetic potential would be stoked to gain as slow as 0.25lbs (100g) of muscle per month doing everything right!


I’d love to hear what your thoughts are. Have you put on muscle doing CrossFit? Do you plan to make any changes to your approach after watching this video? Let us know when you join our Beyond Macros Community.


Additional Research

I’ve also linked up the studies below as references. Check ‘em if you’re keen!

Muscle Hypertrophy: A Narrative Review on Training Principles for Increasing Muscle Mass

Vitamin C-enriched gelatin supplementation before intermittent activity augments collagen synthesis