Some lucky folks can build muscle in a calorie deficit.

But most people with a bit of experience lifting weights can't. At least, not anywhere near fast enough for it to be worth trying.

Before we get into why that is, let's discuss who the people are who can build muscle in a calorie deficit, and why that is. 👇

Who can build muscle in a calorie deficit?

There are three demographics that can build muscle in a calorie deficit:

1. Those new to weight training. 👶
2. Those with very high levels of body fat. 🍩
3. Those who are detrained. 😮‍💨

1) Those who haven’t lifted weights before

People who’ve never lifted weights are blessed to be able to experience the “newbie gains” phase where they’ll make progress and build muscle in spite of what they do.

These lucky sods can get away with stuff the rest of us can't. They can train suboptimally and still experience the most rapid visual transformation of their physique that they’ll see at any stage of their training lifetime. 💪

But that's not to say they wouldn't make even faster progress by giving their body the energy it demands to fuel an expensive process like muscle growth.

2) People who are very overweight

When you're extremely overweight, the body doesn’t seem to mind the additional burden of adding new muscle mass. Even while there’s not enough energy coming in to maintain current body weight.

When you’re carrying too much body fat, even if you're technically dieting, the body doesn’t feel in any way like it’s starving. So it feels no need to scavenge protein and amino acids from the muscles.

This allows overweight people to build muscle even as they lose fat. 😌

3) People who are detrained

This is the third group capable of building muscle even while dieting. Those who built a lot of muscle mass, then lost a lot of it. During a long break from training, perhaps.

Why is this? 🤔

Muscle mass is an investment that pays dividends. 💷

Once you’ve built it, it doesn’t take as much of a stimulus to keep it.

And, if you build it, then lose it, it’s not as hard to regain as it was to build the first time around.

Why is building muscle in a calorie deficit so hard?

Okay, I hear you say. But why is it only these special groups that can build muscle and lose fat at the same time?

Here's why. 👇

How keen your body is to build muscle comes down to one thing:

How much of a priority is it?

At all times, you have to persuade your body that building muscle is a priority. Otherwise it won’t do it.

In the beginning, the stimulus is so new that your body jumps to attention to build more muscle tissue. It’s a huge priority.

…Until it’s not.

At that point, gains slow down.

Other bodily processes start to tussle for the top spot.

Even though you’re still lifting weights, your body starts to deprioritize the muscle building process.

How to keep making progress

So to keep things moving, you have to get cute. 🤝

You have to give your body everything it needs on a silver platter. That means a strong muscle-building stimulus, plus:

• Rest
• Sleep
• Protein
• Micronutrients
• Energy

Ah… That last one! 🪫

Once you’ve got some experience and your body has decided to become more picky about when it builds muscle, energy is one of the things it’ll dig its heels in without.

That’s where calories come in…

What is a calorie deficit?

A calorie deficit is where you’re eating fewer calories than your body burns each day. It’s what most people mean when they say they’re “dieting”. A calorie deficit is essential for losing weight and, more importantly, for losing fat.

If your body burns 2,000 calories a day, on average, and you eat 1,750 calories a day, you’re in a 250 calorie deficit.

How does a calorie deficit work?

Your body needs energy to operate.

It needs energy to produce hormones, move around, even to digest the food you eat.

Food contains energy, which is measured in calories.

Understanding food labels

On a food label, you’ll see this listed under the nutritional information. On a packet of white rice from Tesco, for example, you’ll see “1536kJ/362kcal”.

The listed units of measurement are “kilojoules” and “kilocalories”.

The “kilocalories”, or “kcal” on the right are the ones we’re interested in. In everyday talk, they’re just called “calories”.

Your body needs energy

So, your body needs energy to function, and food contains energy. When you eat, you top up your energy reserves, like fuel in a tank. 🔋

Some foods contain far more energy (or calories) than others.

When you eat more energy than your body needs right away, you’re said to be in a ”calorie surplus.” The energy you’re giving your body is literally “surplus” to requirements.

Storing excess energy

And your body is very good at finding places to store this excess energy for later, when there might not be enough coming in from the food you eat.

If you’ve exercised recently, it’ll store sugars broken down into glucose as muscle glycogen. 💪

Any further excess energy will be stored in the fat cells. This is how you get fatter from eating more energy than your body needs.

How dieting works

In a calorie deficit (a diet), you eat fewer calories than your body needs to operate on a day-to-day basis.

Your body still needs that energy from somewhere, so it dips into its stored reserves. 🪫

On a small scale, this could be as simple as dipping into stored muscle glycogen while you’re in the gym if there’s no glucose circulating in the blood at the time you’re exercising.

On a larger scale, your body will dip into your fat reserves for the slower, gentler energy requirements of your day-to-day life.

Again, this stored energy has mass, and as your body raids its fat stores for more energy to make up for the dietary shortfall and burns it for energy, your scale weight drops accordingly.

What size calorie deficit do you need to lose a pound a week?

If you want to lose a pound a week, you need a calorie deficit of 500 calories a day.

So if you need 2,000 calories a day to maintain your current weight, you’d need to eat 1,500 calories a day to lose about a pound of fat a week.

Not all the weight you lose will be fat. Initially, you’ll see a more dramatic drop in weight as your body drops muscle glycogen and, with it, water weight. 💧

As you’re eating less, you’ll also slowly lose some of the weight you were carrying around in your GI tract as food that’s on its way out. 💩

But over time, you will lose fat. You have no choice. And changes in scale weight over time will reflect that.

How do I know how many calories I burn at rest?

There are online calculators that will calculate your TDEE, or Total Daily Energy Expenditure. 

But the truth is, you (or your coach) is always going to need to adjust these figures based on what you see happening in front of you.

If you take a TDEE figure from a calculator and subtract 500 calories, but after two weeks you’ve only lost half a pound, you’re not in a 500 calorie daily deficit.

Maybe you’re tracking your food intake inaccurately. Or maybe your TDEE was lower than what the calculator promised you. It doesn’t matter. You need to fix the deficit if you want to progress.

Since you’ll never truly know for a week or two, the best any calculator can do is throw you a ballpark figure.

How protein and weight training stimulate muscle growth

Lifting weights triggers something called muscle protein synthesis (MPS). 🏋️‍♂️

MPS is the trigger, or signal, to your body that it needs to build more muscle. And weight training stimulates this signal.

But just like building a house, your body needs raw materials. 🧱

These come from the protein you eat from food. Your digestive system breaks protein down into amino acids. Your body uses these to build new muscle tissue.

So how is this different in the beginning?

In the beginning, when you’ve never trained with weights before, your body can’t get enough. The new stimulus is so powerful, your body will do whatever it can to adapt to it. 🦹‍♂️

Once the “newbie gains” phase has passed, though, adaptations start to slow down.

The novelty of the stimulus wears off. 😪

Now, you’ll need to start giving your body enough energy to fuel all the other processes it’ll prioritise over and above building new muscle mass. You’ll also need to dial in your training approach, your nutrition, and your recovery to make sure your body has the ideal muscle-building environment.

Get this wrong, and you’ll struggle to continue making progress past the first year.

3 Possible scenarios for gaining muscle and losing fat

1) Losing fat and gaining muscle simultaneously

Losing fat and gaining muscle simultaneously is possible for people who haven’t trained with weights before, those with very high levels of body fat, and those who built a lot of muscle in the past, but lost it during a training layoff.

It’s possible for people in these groups because, in these states, the body is either willing or able to prioritise muscle gain as a process. Even if other conditions aren’t optimal.

Past a certain point, the body starts to resist the accretion of new muscle tissue. It doesn’t actively fight against it, but you need to optimise all the variables relevant to building muscle to greater and greater degrees if you want to keep making progress.

2) Losing fat and maintaining existing muscle mass

This is what most people with some training experience should hope for when they look to diet.

In a weight loss phase, they’ll continue training with weights as they have been, and they’ll continue eating plenty of protein (around a gram per pound of body weight). This makes sure the body still has a reason to keep the muscle it has built, and has enough amino acids freely available to support other processes, even while there’s not much energy to go around, so it doesn’t have to scavenge amino acids from the muscles.

Since they’re in a calorie deficit (energy deficit), the body needs energy to survive, and so will pull from its energy reserves. This means fat loss can occur, while as much muscle mass as possible is preserved.

3) Gaining fat and muscle mass at the same time

This is what most people should expect when they’re trying to build muscle.

To build muscle mass effectively after the first year or so, your body needs sufficient energy to encourage it to build (and keep) new muscle tissue.

Muscle mass is metabolically expensive. It has high blood flow demands and high energy demands. Unlike the fat that sits on your body, it’s not relatively inert. It’s much more active, contracting and working all day long. Even if only in a small capacity.

That’s part of why you need to encourage the body to build more of it past a certain point. And part of that encouragement constitutes giving your body enough energy in the form of calories.

So…

Why do you have to gain fat to build muscle? 🤔

Simply put, it’s too tricky to optimise every single necessary variable to ensure you put no fat on while gaining muscle. 🤷‍♂️

For most people, gaining 0.5-1.0lbs of scale weight per week will be plenty. Any more than that, and the ratio of fat to muscle gain becomes unfavourable. You just increase the amount of fat you’ll have to diet off later, taking away from time you could be spending building more muscle mass.

Also, you can’t just force feed more muscle mass onto your body if you're natural.

You can only trigger muscle protein synthesis, and give your body just enough energy and protein to encourage it to perform that process. Then, you recover enough to make sure you’re maximising the strength of the muscle-building stimulus from your workouts. Then, you train that muscle again.

And you repeat that process.

Will I lose muscle mass if I workout in a calorie deficit?

Most trained people (those who’ve been training with weights for more than a couple of years and have seen good progress), will probably lose some muscle mass over the course of months in a calorie deficit.

The goal isn’t to prevent all muscle loss. That would be impossible. But you can certainly minimise it.

To do that:

1. Continue eating plenty of protein. 1.0-1.2g per pound of body weight is a good target while dieting.
2. Continue training hard in the gym.

If you continue stimulating your muscles to grow, and giving your body the materials it needs to build them, while you might not build any new muscle mass, you’ll at least stave off any muscle loss.

3 Dietary approaches to building muscle

What is “maingaining”?

“Maingaining” is a colloquial term weight lifters use to describe a phase where they allow their body weight to creep up over a long period of time.

Lifters will adopt a “maintenance” mindset, where they aim to eat at maintenance calories, but allow themselves the odd treat. The caloric surplus is very small, but it allows them to slowly build muscle while minimising fat gain.

Maingaining represents a mindset shift.

One where lifters focus don’t on a purposeful weight gain or weight loss goal. Instead, the aim is to mostly forget about aggressive goals in the gym altogether.

Many lifters use these “maingaining” phases as breaks from intense focus on the gym. Instead, they focus on other goals in their lives. They keep going to the gym, training pretty hard, and getting their protein in. But they’re not looking to aggressively add or cut weight.

What about “lean bulking”?

A “lean bulk” is where you look to build muscle mass while minimising fat gain.

It’s more intentional than a maingaining phase, since the goal is specifically to build muscle mass and get heavier.

To reflect this, the lifter will intentionally enter a caloric surplus. In stark contrast to the dirty bulk, however, discipline remains at the core of the lean bulk.

High quality food choices remain a priority. That means minimal processed food, and plenty of whole foods. Fruits and vegetables remain staples.

The caloric surplus is small. The lifter accepts a slow rate of weight gain, knowing that they can’t force-feed new muscle tissue onto their body.

This is, truly, what most lifters should aim for when they’re trying to build muscle.

Is “dirty bulking” good for muscle growth?

Dirty bulking is, in almost all cases, an excuse to eat junk food.

Almost always, a dirty bulk involves putting on weight too quickly, making you fatter, faster, for no additional muscle gain.

Dirty bulking encourages bad habits, damages your health (higher blood pressure, worse blood lipids, higher blood sugars) in measurable ways, and has almost no benefits versus eating clean.

The only exception in my opinion is for younger people who have repeatedly tried to bulk, but struggle to put on weight.

For these people, embracing the dirty bulk can constitute a mental reframe. One where the goal is to eat as many calories as possible, no matter the food source.

In the short term, this fixes their struggle to put on weight.

But there’s still no advantage to pushing up calories by eating donuts and pastries, rather than olive oil and white rice. Both of which are calorie-dense, without the drawbacks of being addictive and inflammatory.

So what’s the best dietary approach to build muscle?

A small to modest caloric surplus, with a diet consisting of whole, unprocessed foods, is the best dietary approach for building muscle.

I am 100% bought-in on this. 💯

There is no better approach. An excessive calorie surplus only makes you gain too much fat. When you eat too much junk food, you:

• Become addicted to the sugar, fat, salt combination.
• Desensitise yourself to the tastes of food that’s good for you.
• Guarantee an excessive calorie surplus, and therefore excessive fat gain.
• Inflame your gut.
• Deprive yourself of micronutrients.

What are the benefits? 🤔

• The food tastes good.

But how do you feel after eating it?

That’s right… terrible. 😷

And your body follows suit.

A small surplus and a healthy diet has many benefits:

• You give your body an abundance of the nutrients it needs to thrive.
• Your sleep is better.
• Your energy is higher throughout the day
• You have better workouts, and recover better from them.

But perhaps the biggest (selfishly), is you can push the weight gain phase for longer. This means greater muscle gain from a single weight gain phase, and less time spent dieting off the excess fat.

And by the way, a “small surplus” doesn’t mean zero flexibility. ❌

It doesn’t mean you can’t let your hair down on date night, or have a few beers with the boys. 🍻

But it does mean you can’t throw caution to the wind, call the curry place on Monday, the pizza place on a Wednesday, eat slabs of chocolate in the evening on Friday, then get obliterated with booze and all the liquid calories it contains on a Saturday night.

Only to come home and order more food from the most-used app on your phone.

Instead, take a slow and steady approach, with a few deviations thrown in for sustainability, and because life is short.