Can You REALLY Build Muscle in a Calorie Deficit?

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Weight Loss Coach and Owner at 9 To 5 Nutrition
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Ok, I get it, we all want to be 200lbs and sub 10% body fat.

Of course we do

I mean, why wouldn’t you?

I don’t think I’ve ever met anyone who doesn’t want MORE muscle and LESS fat. Whether you’re a guy or a girl, young or old, supermarket shelf stacker or invest banker, this is the holy grail for all of us.

The good news is that building muscle while in a calorie deficit is technically possible.

The bad news is that is pretty damn difficult.

The second bit of bad news is that even if you can achieve it, the level of muscle growth you’ll achieve will be so small and insifican’t, that you won’t even notice it.

But it is possible.

But just because you can, doesn’t mean you should…

Spoiler alert: I’m going to spend the rest of this post trying to convince you NOT to try and build muscle AND lose fat at the same time, but first, let’s understand the processes behind those two things…


A calorie deficit is just the term for being in a state whereby you’re eating FEWER calories than you use each day.

What the hell does that mean?

Well, let’s say you used 2000 calories a day.

If you ate 1,500 calories a day, that would mean you were in a 500-calorie deficit, and you’d lose roughly 1lb (0.5kg) per week.

If you want to work out what your calorie deficit should be, use this handy calculator

Step 1: Basic Information
Step 2: Activity Level
Step 3: Select your goal

Sounds really simple, doesn’t it?

That’s because it is.

But just because it’s simple, doesn’t mean it’s easy.

The key to maintaining weight loss is to consistently be in a calorie deficit. That doesn’t mean focus on it for one week then go wild.

It means being in a calorie deficit, week after week, month after month.

It also means monitoring your results closely, and changing things up when your weight plateaus because that WILL happen.


To be clear, muscle building is a totally separate process to fat loss.

You can’t ‘convert fat into muscle’

There is no such thing as ‘lean muscle’ or ‘fat muscle’

They are two distinct, unrelated processes (although they can affect each other indirectly).

So how does muscle building work?

Well, when you lift weights, you recruit muscle fibers. If you lift intensely enough you’ll tear some of those fibers.

When you rest, those fibers will be rebuilt a little stronger and thicker than last time.

This is an incredibly s l o w process.

To create the ideal environment for muscle growth to occur, you should be in a calorie surplus, i.e. eating MORE calories than you use on a daily basis (yes that’s the OPPOSITE to a calorie deficit).

You should also be eating around 1.6-2.2g of protein per kg of bodyweight.

The mistake most people make with building muscle is that they’ll eat WAY more calories than they need, and while they might gain some muscle, they’ll also gain a lot of fat along with it.

The problem is, if you gain 5lbs of muscle by 10lbs of fat, you’ll most likely end up looking worse than you did when you started.

Yes you’ll be bigger, but you’ll be MUCH less defined, and you won’t be able to see the muscle you’ve built.

You’ll want to diet off all that fat, which takes time.

Time you could be using to build muscle instead.

So how many calories do you need to build muscle? Well probably only around 50 calories above maintenance per day STUDY

So if you need 2,000 calories to maintain your weight, you only need 2,050 to build muscle.


So , you want to avoid gaining too much fat when you build muscle.

Well, what if you just killed two birds with one stone and build muscle and lost fat AT THE SAME TIME…

Aka, body recomposition

Building muscle in a calorie deficit IS possible, but that doesn’t necessarily mean it’s the best way to go about it.

Let’s get scientific for a second.

This study suggests that a surplus of 350-480 calories a day is a good starting point for people looking to build muscle, but I’d actually disagree with this.

Here’s why;

For people that have been lifting weights for a while, 1-3kg of extra muscle per year is the best you could hope for. Side note – if you want to know how much Muscle I built in a year, check out this other post!

You’ll never really KNOW how much you could potentially gain, so it’s best to have a realistic target in mind.

So let’s say we aim for 3kg of muscle in a year.

It takes roughly 5,940 calories to build 1kg of muscle (or 2,700 to build 1lb), so that means over a year we’d need to eat in a surplus of 49 calories per day.

Yes 49 extra calories. That’s half a scoop of protein powder or about a quarter of a protein bar. Lol.

That means that if you maintain your weight on 2,000 calories per day (again you can use the calculator above to work this out), you only need 2,049 per day to build 3kg of muscle in one year.

The process of digesting and synthesizing protein is calorically expensive, so it might take more calories than that.

You might then want to aim for an extra 100 then.

To help you make a decision, I threw this table together, assuming your maintenance calories are 2,000 per day



No, you shouldn’t try to build muscle in a calorie deficit, here’s why.

Whether you’re trying to lose fat or build muscle, you really want to create the OPTIMAL conditions for doing either of those things

The optimal conditions for losing fat are a calorie deficit of between 300-700 calories per day, and an exercise plan that doesn’t stimulate appetite to the degree that you might not be able to stick to that deficit.

The optimal conditions for building muscle are a calorie surplus (granted, a very small calorie surplus) and enough energy to to train with an intensity that allows you to progressively overload the muscles (i.e. lift more weight over time).

Can you see where these two things start to conflict?

If you really want to focus on building muscle, you need energy to push yourself.

Energy comes from calories, and you need to limit calories if you’re in a calorie deficit.


Rather than trying to build muscle (even though it’s technically possible) what you should be trying to do is maintain what you already have.

I know that sounds boring, and isn’t as glamorous as


But it’s realistic and achievable.

And remember, even if you don’t gain any muscle at all, but you keep what you have and lose a significant amount of body fat, you’ll look a lot more defined and a lot bigger anyway, which is ultimately what you want, right?

Building muscle while losing fat (body recomposition) is very difficult, but even maintaining muscle while losing fat can be tough, here are five things you can do to make it more likely that you’ll retain muscle in a calorie deficit

Don’t Change Your Mindset

Just because you’re in a calorie deficit, little else should change.

You should be still training with the same intensity, volume and frequency that you were before you went into a deficit. Arguably, you should be training even more intensely than you were before because you need to give your body clear signals that you want to hold onto the muscle you have.

Implement Progressive Overload

How do you make sure you’re training intensely? Incorporate progressive overload into your training.

This means adding an extra rep, or a little extra weight each time you train.

Use an app like Rep Count to ensure you’re progressively overloading, if you are, you can’t fail to at least maintain the muscle you have.

Rep Count App Volume Load

Keep Protein Intake High

Not quite as important as progressive overload, but still really important.

Regardless of where you’re in a deficit, losing fat or trying to gain muscle, you should always be looking to get a significant amount of protein in your diet.

What is ‘signficant’? Most people should be aiming for around 1.6g-2.2 grams of protein per Kg of body weight.

Any more won’t do any harm, but remember; the more protein ou eat, the fewer calories you’ll have for carbs which you’ll need for energy. Speaking of which…

Calorie and Carb Cycle

When you’re dieting, you have fewer calories to play with so you’ll need to be careful how and when you use them.

If you want to have the best chance of building or maintaining muscle, you’ll need to make sure you have adequate fuel for your workouts, so make sure you’re consuming a good amount of carbs (50-100g) around an hour or two before you train.

That energy may be all you need to push out that one extra rep, which could make all the difference.


This goes without saying (or it should anyway), but sleep is crucial for gaining and maintaining muscle.

Sleep gives the body a chance to rest and recuperate, which is when muscle repair takes place. 

Make sure you’re getting 7-9 hours per night, every night.


We’re casually talking about muscle gain here like it’s something that happens quickly, and something you’ll notice immediately.

Newsflash: You won’t.

Muscle gain is so gradual that you won’t notice it, so how can you be sure that you’re gaining and/or maintaining muscle when you’re in a calorie deficit?


DEXA is a whole-body scan that’ll give you a detailed picture of your muscle-to-fat ratio. This is the most accurate way to measure changes in muscle mass.

The downside is, DEXA scans are really expensive (around £150 a pop last time I checked) and still aren’t 100% accurate.

Gym Performance

By and large, if your performance in the gym improves, then you can be confident that you’re at least maintaining the muscle you have.

What’s more likely is that you’re gaining muscle. More muscle mass leads to more strength, which leads to more muscle, etc etc

Progress Photos

We all look at ourselves in the mirror multiple times a day, so it’s unlikely you’ll notice very gradual changes in muscle mass.

Regular progress photos (every month, for example) however will allow you to back and compare.

Just remember to take the photos in the same location in the same lighting, at the same time of day.


Measurements are pretty objective so they’re a good way of judging if muscle growth has taken place.

The only issue is that if you’re in a calorie deficit you’ll be losing fat too, so if your limb measurements ARE going down, remember this is likely because you’re losing fat, not necessarily muscle.


The fit of your clothes will also give you a good clue as to what’s going on.

If your shirts and t-shirts are getting looser around the waist, but staying just as tight on the arms, chest, back, and shoulders you can be confident you’re losing fat and at least maintaining muscle in a deficit.

Similarly, if the waist on your jeans is getting looser but they’re just as tight around your quads and hamstrings, that should also tell you you’re losing fat and maintaining or gaining muscle.

In reality, should be using all these signals as feedback in combination since there’s no one perfect way of gauging that you’re definitely gaining or maintaining muscle


The sad reality is, a lot of people switch between wanting to lose fat and wanting to build muscle, they spin their wheels and never get near to either goal.

This is because when most people start getting lean, they feel like they’re losing muscle and they stop.

Conversely, when people start building muscle, they feel like they’re gaining too much fat and stop.

If this sounds like you, stop.

So many people get caught in this never-ending cycle and never significantly improve the way they look

In my opinion; everyone should follow this formula for being muscular and lean.

  1. Look in the mirror. Are you as lean as you want to be? Be honest with yourself.

2a. If yes, cool, start slowly building muscle 

  1. If the answer is ‘no’, then focus on getting lean first (because it’s a faster process than building muscle).
  1. Aim to lose 0.5%-1% of your body weight per week (that’s 1-2lb per week if you weigh 200lb)
  1. Keep training as intensely as you were before, at least attempting to progressively overload
  1. Once you reach your desired level of leanness, then start building muscle
  1. Remember that building muscle (if you’re natural) is an incredibly slow process; have it in your mind that you’ll only gain a maximum of 6lb (3kg) per year 


Can you gain muscle on a 100 Calorie Deficit?

Hell yes.

If you’ve paid any attention at all to this post, you’ve probably noticed that I’m against attempting to build muscle in a deficit. HOWEVER…

If you’re going to ignore my advice and do it anyway, you’re best off going for a very small deficit, as it’ll mean you’ll have more calories in your diet to train intensely.

Remember, a 100-calorie deficit will mean you only lose around 0.2 lbs per week, or 0.8 lbs per month.

Will you definitely lose muscle in a deficit?

While it’s possible to lose muscle mass in a calorie deficit, the extent to which this occurs can vary depending on several factors, including:

  1. The degree of calorie restriction: The more severe the calorie restriction, the greater the likelihood of losing muscle mass.
  2. Your protein intake: Consuming enough protein can help preserve muscle mass during a calorie deficit.
  3. Your exercise routine: Resistance training and other forms of exercise can also help preserve muscle mass during a calorie deficit.

Therefore, if you want to minimize muscle loss while in a calorie deficit, you should aim to consume adequate amounts of protein and engage in regular resistance training exercises. Additionally, it’s important to note that losing some muscle mass may be inevitable during a calorie deficit, but you can take steps to minimize the amount of muscle lost.

Do you need carbs to build muscle?

Carbohydrates are the body’s preferred source of energy for high-intensity exercises, such as weightlifting, which is an essential component of building muscle. 

Carbs replenish muscle glycogen stores (the energy held within muscle tissue), which can become depleted during exercise and can impair muscle recovery and growth.

Carbohydrates also stimulate insulin release, which is a potent anabolic hormone that can help to promote muscle protein synthesis (the process by which muscles repair and grow). Insulin can also help to prevent muscle breakdown and promote muscle recovery after exercise.

So while it’s possible to build muscle without consuming carbohydrates, including carbohydrates in your diet can provide indirect benefits for muscle growth.

How much protein should you eat to build muscle?

A general guideline for protein intake for muscle building is to consume between 1.6 to 2.2 grams of protein per kilogram of body weight per day. For example, if you weigh 70 kilograms (154 pounds), you would aim to consume between 112 to 154 grams of protein per day.

It’s important to note that the upper end of this range may not be necessary for everyone, as research suggests that consuming more than 2.2 grams of protein per kilogram of body weight per day does not provide any additional muscle-building benefits, but if you like protein, hey, go for it.

It’s also important to distribute your protein intake evenly throughout the day and consume protein-rich foods both before and after exercise to support muscle recovery and growth.

What’s the best diet to build muscle?

here isn’t a “best” diet for building muscle, as individual nutrition needs and preferences can vary widely. However, there are several dietary principles that are generally recommended for supporting muscle growth:

  1. Sufficient protein intake: As mentioned earlier, consuming enough protein is essential for muscle growth. Aim for 1.6 to 2.2 grams of protein per kilogram of body weight per day, distributed evenly throughout the day.
  2. Caloric surplus: Consuming more calories than your body burns (i.e., a calorie surplus) is necessary to support muscle growth. Aim for a modest calorie surplus of around 10% above your total daily energy expenditure (TDEE).
  3. Adequate carbohydrate intake: Carbohydrates provide energy for high-intensity exercise, and can help to replenish muscle glycogen stores. Aim to consume complex carbohydrates, such as whole grains, fruits, and vegetables, to support muscle growth and overall health.
  4. Sufficient healthy fats: Consuming sufficient healthy fats, such as those found in nuts, seeds, avocado, and fatty fish, can help support hormone production, which is essential for muscle growth and recovery.
  5. Consistent nutrient timing: Eating nutrient-dense foods both before and after exercise can help to support muscle recovery and growth.

In addition to these dietary principles, it’s important to stay well-hydrated and consume a variety of nutrient-dense whole foods to support overall health and well-being.


You can build muscle in a calorie deficit, but unless you’re an elite sportsperson or taking steroids, then you shouldn’t aim to do this.

Instead, pick a goal (either losing fat our building muscle) and tailor everything towards that.

If you’re not sure what your goal should be, ask yourself if you’re happy with your current level of leanness (i.e muscle definition), if the answer is ‘no’, aim to lose fat until you’re happy with how lean you are, their aim to slowly build muscle over time from that point.

REFERENCES 📒,~0.4g%2Fkg%20protein.

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