How to Build Lean Muscle 101: A Detailed Guide

Getting fit isn’t always about dropping a few pounds.

Some people want to develop strong, powerful bodies, and gain functional muscle mass instead – people like you.

Do you want to know the truth about building lean muscle? Then it’s time to throw out any bro-science with the protein-doused bathwater and face the facts. Here is your in-depth, no-nonsense guide to stacking fat-free mass.

What is lean muscle?

Lean muscle is a strange one. It can mean one or two things depending who you speak to.

Your gym-buddy or personal trainer might say lean muscle is the type not clouded by fat. So, in a way, it’s a loose term to describe body composition – aka your fat to muscle ratio. When you’re training to build lean muscle, you’re looking to stay or become defined, not just bulky.

Then, on the other hand, there’s the elephant in the room. All muscle is lean isn’t it? After all, there’s no such thing as fatty muscle. They’re two different types of tissue and can’t occupy the exact same space.

For the sake of this article we’ll assume you want to build lean muscle with plenty of definition. We’re not going to go too much into the smooth muscle surrounding organs or cardiac muscle. Instead, it’ll all be about skeletal muscle.

Muscle tissue is fascinating. It’s full of tiny cells that contract and lengthen to create movement. Flex your bicep right now and feel it contract, while your triceps relax.

Notice the arc your forearm swung in? You can thank the hundreds of thousands of muscle fibers inside your bicep for that.

Opposing muscles work like two teams to move a joint. But instead of fighting each other, they cooperate.

When one side pulls hard on its boney attachment, the other relaxes. To reverse the movement, the relaxing side takes its turn to tug and moves the joint back in the opposite way.

Only functional lean muscle can make all this magic happen – fat can forget about it.

How do you build lean muscle?

When you decide to ditch all the gym-floor mysticism and learn some real science, building muscle isn’t complicated. It can be if you want to go down that path, but fundamentally things are pretty simple.

First, you need to give your muscle fibers a reason to grow. Exposing them to increasing amounts of tension encourages adaptations to happen.

You already know how to do this already – resistance training. You break the muscle fiber down, allow it to recover, and then repeat the process. We’ll get into this properly in a short while.

Equally as important and training is your nutrition. After all, what you eat will without a doubt determine the amount of body fat you store.

It’ll also provide the building blocks to re-forge torn muscle fibers and help them grow bigger, better, and stronger.

So, while we’re on the subject of diet, let’s dive into nutrition. 

Nutrition is key to build lean muscle


Nutrition is the delivery of integral materials to cells and organisms. Diet is the food you currently eat, the water you drink, and the supplements you take. Nutrition is the concept; diet is what you’re doing right now.

Health is promoted by an all-round, well-balanced diet. Muscle building isn’t any different, especially if you’re looking to keep lean.

A well-balanced diet is one that features a health-promoting mixture of the major food groups, split into other subgroups.

Eating right requires a touch of regulation and vigilance. Everything comes down to monitoring your intake of a wide variety of fruits and vegetables; alongside muscle building proteins and healthy fats.

These aren’t the requirements for an Instagram-enviable physique, no no. It’s the absolute minimum for staying healthy.

Nailing your nutrition is essential for building lean muscle. Even people with a raging furnace for a metabolism can benefit from dialing in their diet. Remember, genetics isn’t everything, and good can always be better.

Your body is a machine. It can either be well-oiled and filled with premium fuel; or neglected and driven by cheap, dirty gas. Which one are you going to choose?

Okay, we’ll admit, the whole ‘your body is a machine’ analogy is so easy. But let’s not pretend it doesn’t fit perfectly. Overused yes, but outdated no.

We’ll be covering exactly how to fix your nutrition later. Next up, it’s time to hit the training room.

People in gym


You can improve your muscle mass by resistance training. Think pumping iron over running a marathon; or squats instead of a steady jog.

Resistance training is exactly what it says. You actively take your body and use it to move something against a force.

This could be grabbing a barbell and pressing it overhead, stretching out a resistance band, or pulling on a weighted cable. Performing a pull up or pistol squat with your own bodyweight counts too.

Then you have isometric training too. Typically, when you think of contractions, you imagine your muscle changing length. But believe it or not, you can still generate force without much movement.

Picture yourself squeezing hard on a medicine ball or pushing against a solid wall with as much pressure as you can muster. What you’re seeing is isometric contraction in action.

It might not be everybody’s go-to, but studies show supplementing your workouts with isometric exercises can still increase strength[1]. They’re also a great alternative for working around inevitable injuries.

Now you’ve wrestled with what resistance training is, it’s time to see how it works.

How resistance training works

To put it bluntly, resistance training has two unique effects on muscle. Firstly, it causes tension, which creates tiny microtears inside your muscle fibers.

With the right rest and nutrition, these fibers are rebuilt and fortified by the proteins you eat. Scientists call this turnover process muscle protein synthesis (MPS)[2].

Another scenario triggered by resistance training is metabolic stress, a physiological response to low energy. Metabolites accumulate inside the muscle and cause; hormonal release, cell swelling, and hypoxia among other components.

Together, these reactions trigger anabolic signals that influence muscle growth[3]. Of course, MPS plays a huge part in this part too.

When MPS overtakes breakdown, muscle can grow[4].

The proper term for your size gains is muscular hypertrophy, which represents an increase in individual cross-sectional muscle fiber size. It’s actually the expansion of each tiny fiber that adds up to a much bigger bicep.

Man exercising bicep

Inflicting trauma can cause two main types of hypertrophy:

  • Sarcoplasmic hypertrophy – when the volume of non-contractile sarcoplasmic fluid increases inside the muscle to enhance endurance with lower loads. Size is increased, but strength gains might not match
  • Myofibrillar hypertrophy – strengthens the myofibril (contractile protein) while also increasing size and density. This super-compensates muscle fibers so they’re better adapted to lifting a heavy load. The body performs this type of hypertrophy as if responding to an injury.

On top of all this you have the one concept that binds all lifters – progressive overload. Making an effort to increase the demands you force on your body is integral to development[5].

After all, if you don’t keep asking for more, why would your muscle keep improving? It’s like the old saying; if you don’t ask you don’t get.

Do you know someone who’d used the same routine, day in day out or years and not got bigger? Chances are they’re cutting out this key concept.

How to structure your diet to build lean muscle

Ditch the dirty bulk. Follow these tips to build hard, lean muscle.

Eat in a calorie surplus

Building muscle is much more fun than trying to burn fat. While it’s not absolutely essential to eat more than your daily needs, it could help[6].

Are you already lean? If so, adding 10-20% on top of your usual calories can kickstart a tidy clean bulk.

The slight surplus of energy could feed and fuel your muscle to grow faster, without too much fat gain. Don’t be tempted by the cheeseburger siren calls of a dirty bulk, it’s never worth it.

Okay, but what if you’re a little overweight? In that case, forget the surplus. Eat a protein-rich, well-balanced diet while maintaining a slight calorific deficit.

You don’t need to go crazy, take a healthier approach with a 10-20% reduction. When you’ve leaned out, try a smart surplus.

Calorie Surplus

Eat more protein

Aggregating your amino acids on your plate should always be a priority. After all, it’s these building blocks of protein that reconstruct damaged muscle fiber.

According to the International Society of Sports Nutrition[7];

“For building muscle mass and for maintaining muscle mass through a positive muscle protein balance, an overall daily protein intake in the range of 1.4–2.0 g protein/kg body weight/day (g/kg/d) is sufficient for most exercising individuals.”

So, if you’re an average 84 kg male, you need at least 117.6 g of protein every single day for maintenance. But that’s just the bottom-line.

To build muscle, you should aim for up toward the two gram per kilo mark, or a little higher. An old-school mantra from the Arnie days is to eat a gram of protein per pound of bodyweight.

In the same report, the ISSN say that athletes should focus on whole food protein sources. These should ideally contain all the essential amino acids too, because they’re needed to instigate MPS.

Make sure to eat protein at every meal to aggregate your daily aminos.

Another priceless ISSN insight is how just 30-40 g of pre-sleep casein ramps up overnight MPS without effecting fat burning. So, if you want to enhance your sleep growth, take a low-cal casein shake before hitting the hay.

Avoid macro balance mistakes

Balancing your macros has never been easier. Back in the day you’d need a calculator, notepad, and mountains of time that’d be better spent in the gym. But not anymore.

Today, you can download an app to do the numbers work for you. The rub-off is you can set up your diet with pinpoint precision in a matter of minutes.

Avoid the most major muscle building pitfall, and don’t dismiss any food groups. Here’s why:

  • Carbohydrates provide energy
  • Fats are essential for hormone health and nutrient absorption
  • Protein provides amino acids to rebuild muscle

Naturally, there’s a lot more to each macros than we’re giving credit for. The roles above are just your main concern for muscle building. Try using this ratio to enhance lean muscle growth:

  • 25-35% protein
  • 40-60% carb
  • 15-25% fat

Traditional bodybuilding advice is to go super low carb to bulk with definition. Yet, when you look at the science, it’s not a smart move. Not only do carbs provide energy to train harder[8], but co-ingestion with protein could increase MPS[9] too.

Bottom line – don’t believe the hype, trust the science.

Creating a training regime to build lean muscle

If abs are made in the kitchen, lean muscle is forged in the gym. Here are a few key concepts to consider when creating your training regime. 


Despite what the bro-science says, cardio doesn’t burn muscle. Sticking to sprints, a regular morning run, or a handful of boxing rounds won’t ruin your gains.

On the contrary, regular cardio might could benefit lean muscle building.

Studies show that cardio workouts are a great way to burn through calories[10]. Fitting a few sessions into your week alongside weightlifting appears to be the best becoming lean[11].

Maximize muscle maintenance and time efficiency with HIIT over prolonged jogging. An average HIIT workout takes between 10-30 minutes but uses a ton of energy.

According to one study, a single 30-minute session can torch 25-30% more calories than other types of training[12].

You might only need to use two or three HIIT sessions a week. Just remember to keep an eye out for warning signs of overtraining.

Cardio machines

Lifting (heavy) weights

You don’t need to lift heavy weights to build lean muscle – but it helps.

Lifting heavy weights challenges your body using the mechanisms we looked at earlier. By chalking up, wrapping the hands around a barbell and ripping it from the floor, you fire your physique into action.

You create those all-important microtears and encourage each fiber to grow back bigger.

When you up the weight, you also increase intensity. You pile on the percentage of your maximum capacity you use, and in turn, must hit lower reps.

Going heavy with low reps strengthens the fiber and creates dense, compact muscles. Scientists call this myofibrillar hypertrophy.

The body treats the trauma caused by heavy lifting as an injury. So, instead of just improving the fibers volume so it can store more energy for low-weight reps, it overcompensates and increases its density too. This is how you get stronger, not just bigger!

A final reason to lift heavy is it instigates a boost in testosterone production[13][14]. The effects might even last in the long run too; playing a part body fat distribution, as well as promoting MPS[15].

Compound exercises

No lean muscle workout is complete without compounds. Okay, maybe we’re not the official rule makers, but we make a pretty good case.

Compound exercises are multi-joint movements; think squats, deadlifts, presses, swings and anything that doesn’t isolate a body part.

Hitting a squat, for example, will work your hamstrings, quads, glutes, core, and thoracic. Your favorite bicep curl routine, well, the clue’s in the name.

Hitting many of the major muscle groups in one go allows you to shift heavy loads. As a result, you can reinforce your body to become stronger than using isolation moves alone[16].

Another reason to crush compounds in every workout is efficiency. Why spend an entire week trying to work every body part when one workout will suffice? Forget the bro-split and use full-body training instead.

Studies show that working a muscle twice or three times a week creates a spike in MPS at each event[17].

So, rather than thrash a muscle to death once every seven days, hit the whole body three, four, or five times with full-body workouts[18].

Load up the barbell and get busy with those compounds. 

Barbell in gym
Compound exercises are multi-joint movements.

Try supersets

As corny as supersets sound, they’re legitimate for forging lean muscle. The idea is to hit two exercises back to back, with minimal rest in between.

A common supersetting technique is to use opposing muscles – aka agonist/antagonist sets. You might find your program calls for squats followed by overhead press; or bicep curls followed by cable triceps pushdowns.

Compound sets using the same muscle groups are another option too.

You should double your rest times post-superset to promote recovery and match volume-load[19]. After you’ve hit the final rep of the second set, drop the bar and take a twice as long break.

Experts say that supersets enhance training efficiency by condensing your work-to-time ration[20]. So, if you’re constantly chasing the clock, consider them your new training partner.

More tips to build lean muscle

Fix your sleep

Studies show that how well you sleep has a huge impact on fat-free body mass[21][22]. Simply not getting enough quality zeds makes it harder to build muscle and stay lean[23].

The fix? Aim for eight hours of consistent sleep every night. Turn off your phone, stay away from screens, and establish a healthy evening routine. Your lean muscle gains will thank you for it.

Drink more water

Who’d have thought hydration could be the key to a lean, muscular physique? Yet, a lot of people totally underestimate the hold hydration has on their body.

Water plays a vital role in transporting nutrients around your body. It also acts out a part in waste removal, maintenance of cell volume, and thermoregulations.

Without enough of the wet stuff, your muscle performance, size, tone, and energy all suffer! You won’t recover as well between gym sessions either.

Studies also suggest that dehydration slows down fat burning; whereas drinking enough water promotes leanness[24][25][26]. So, if you can’t shift your belly fat, poor hydration habits could be holding you back[27]

drink more water

Too much fasting

Using intermittent fasting to get lean is a time-tested tool. But there’s more to fasting than fat loss.

Research has revealed that short-term fasting helps hike-up your metabolic rate and muscle backing hormones; while also changing the function of health-promoting genes[28][29].

Setting the clock for a short-term fast may also help reduce cancer risks, heart disease factors, and inflammation too[30][31][32]. That’s not bad for a few extended hours of not eating.

Notice how we say short-term, not ongoing? Too much fasting could make it hard to take in all the nutrients need to stay healthy, never mind build solid lean muscle[33]. Chances are, you might not get enough extra calories either, or your RDA of protein.

Bottom line – avoid long fasts unless guided by a medical professional.

Don’t focus only on one body part

Recall the crushing power of compound exercises? Remember how versatile they are for building fat and burning muscle? In that case, this point speaks for itself.

Try not to focus too hard on one single body part. See your physique as a complete picture and prioritize full-body health over anything else. It’s normal to have lagging body parts, but the key isn’t to just try to spot fix one area.

Keep hitting your compound lifts, nail your nutrition, and add a tad more attention where needed. Don’t become obsessed by one body part.


How long does it take to build lean muscle?

Muscle growth at different rates in all of us. As a general rule, though, you should start to see results in as little as four weeks. After six weeks you should notice a considerable change.

How do I build lean muscle without bulking up?

To build lean muscle without bulking up stay away from overeating. You should also focus on more strength specific workouts, instead of constantly performing hypertrophy sessions.

Strength workouts consist of lower reps (1-6) with heavier weights and longer rest, whereas sarcoplasmic hypertrophy is better achieved by higher reps (10-16) and lower weight with shorter rests.

Do I need heavy weights to build muscle?

No, needing heavy weights to build muscle is a myth. According to one study from 2016, it’s completely possible to build muscle with light weights, so long as sufficient volume load is established.

Volume load is when you multiply working weight, by sets and reps.

In other words, you can if you work hard enough. You’ll probably just have to hit higher reps.

But, if you want to grow in considerable size like a strength athlete, bodyweight can only take you so far.

build lean muscle - weight training

Can you lift weights and not bulk up?

Lifting weights will not automatically bulk you up. See weightlifting as a tool to shape your body; burning fat and accentuating your natural physique instead of just building it.

If you don’t hike-up your calories by a considerable amount and focus on hypertrophy, you shouldn’t bulk up. 

The Final Word

Building lean muscle doesn’t need to be complicated. Follow the fool-proof protocols outlined in this guide and start forging yours today.

The trick to above-average gains is mastering the basics. Go the extra mile, eat nutritious wholefoods, and use the best supplements.

Sleep well, prioritize recovery, and optimize your gym routines with compound exercises. If you put in the effort, your progress will speak for itself.

Remember, it’s not where you start out that matters – it’s where you’re going. It’s time to put your new tools to use.



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