How to Maintain Muscle When Losing Fat in a Calorie Deficit

You wonder if you can do this anymore…

It’s like every time you try and lose body fat you just end up skinny, or worse, skinny fat. Stuck in some no-man’s-land between where you want to be and where you are.

You think you’re doing everything right but now you’re just not sure. It’s tempting to pack it all in and give up, but you didn’t get into this fitness game just to give up and walk away when things don’t go your way.

You’re here to better yourself; to perform better, feel better and look better.

What’s going on? 

You know if you can lose fat and keep your muscle mass you’ll look great.

You’ll look good on the beach, be confident topless and better yet, look great naked.

You know that’s the goal, but it never seems to happen to you.

Fear not, this post is written for you and below we will look at a number of strategies you need to use to maintain and even build muscle mass when in a calorie deficit.

Let’s dive in.

Train Using Heavy Weights

This is a must!

Don’t make the mistake of jumping on the ‘light weights burn fat’ bandwagon.

All this does is fast-track you down the path to fat and muscle loss, which will leave you looking small, feeling weak and quite frankly being skinny fat. You know, the not enough muscle to be lean but also too much fat to lean look…skinny fat. 

If you don’t want your body to think you don’t need your muscle mass and start using it for fuel you need to give it a reason to hold on to it.

Lifting heavy is the best way to do this.

Research (1) has shown that;

“strength training significantly reduced the loss of FFM [fat-free mass i.e. muscle] during dieting”.

This was supported by another study (2) which concluded that;

“[an] intensive, high volume resistance training program resulted in the preservation of LBW [lean body weight i.e. muscle] and RMR [resting metabolic rate i.e. calories burnt at rest] during weight loss with a VLCD [very low-calorie diet].”

Note: I’m not advocating a very low-calorie diet! We will get to calories further down the page.

But wait there’s more…

In addition, to the above already very compelling evidence this yet another study (3) that shows that;

“resistance exercise prevents the normal decline in fat-free mass and muscular power and augments body composition [and] maximal strength.”

So, you know you need to train using heavy weights but what’s the best way to do this?

Focus On Compound Movements

Compound movements are movements which work multiple muscle groups through multiple joint actions and because you’re using multiple muscle groups you can generate a lot more strength and power, which in turn means you can lift more and have a greater capacity for growth.

This means your focus should be on exercises like the following:

  • Bench presses – incline or flat
  • Shoulder presses – standing or seated
  • Deadlifts – conventional, Romanian, trap bar, sumo
  • Rows – bent over, Pendley, single arm
  • Squats – lunges, pistols, step ups, leg press
  • Pull-ups or chin ups
  • Dips

When training in a calorie deficit you’re training goal should be at a minimum to maintain your strength, but what rep range should you be working in to do this?

A research study (4) set out to see what number of repetitions would result in the fastest improvement in strength. They took 199 male college students and split them into 9 groups. Each group trained with different repetitions per set from the following set of repetitions; 2RM, 4RM, 6RM, 8RM, 10RM & 12RM.

They were tested before and after completing a 12-week progressive program and researchers concluded that the optimum number of repetitions for strength was between 3 and 9 reps.

What does this mean for you?

Train with the heaviest weight you can in the 3 – 9 rep range whilst maintaining good form and aim to increase this using progressive overload continually over time.

It’s as simple as that.

Lower Your Overall Training Volume & Frequency

When eating a calorie deficit, you’re feeding your body less energy than it needs every day to create a negative energy balance and encourage weight loss, predominantly through the loss of fat. 

This means your body won’t be able to repair itself or recover as fast and its capacity to bounce back from training sessions will be diminished whilst you’re in a calorie deficit. 

For this reason, you want to be careful with how often you train and how much training you do.

Here’s why…

When you lift weights, you damage the cells in your muscle fibres which signals the body to increase protein synthesis rates to repair this damage (5). Your body then adapts by adding new cells which make your muscles bigger and stronger (6).

To build muscle the rate of protein synthesis must be greater than the rate of protein breakdown and this is where it gets tricky.

You already know that to lose fat you need to be in a calorie deficit.

The problem is, when eating in a deficit your body reduces its rate of protein synthesis, which directly impacts your ability to create new muscle fibre cells (7).  Therefore, if you train too much when in a calorie deficit your body will struggle to maintain adequate protein synthesis rates to preserve or even build muscle.

It’s for this reason that you should reduce your training volume and intensity when in a calorie deficit.

Remember your goal when trying to lose fat is to mainly to preserve muscle mass.

How Often Should You Lift Weights When In A Calorie Deficit?

Due to your body’s reduced capacity for recovery, you need to be more strategic when choosing your training plan in a calorie deficit.

Your priorities should be:

  • A training plan that allows you to build or maintain your current strength as best as possible*
  • A training plan that allows sufficient periods of rest and recovery between workouts

*some strength loss is normal especially after you’ve been in a calorie deficit for a prolonged period of time.

It’s for this reason I prefer a 3-day split when training in a calorie deficit as this allows me to work out on non-consecutive days whilst also not training the same muscle groups within 48-72 hours of the previous workout. 

Using 2 workouts, split across 3 days i.e. Monday, Wednesday and Friday allow you to train with intensity and purpose in the workouts you do, without risking excessive volume to the point where it negatively impacts your progress.

What About Sets, Reps & Rest Times?

First and foremost, avoid training to failure when in a calorie deficit.

We’ve already talked about the role of protein synthesis and your body’s reduced ability to repair itself when in a calorie deficit so the reasons should be obvious.

Training to failure not only drastically increases the work your body needs to do to repair itself but it’s also not necessary for you to do this to maintain your strength.

Recommendations for sets, reps and rest times are;

  • Always aim to leave a rep or 2 in the tank
  • Rest 2 – 3 minutes between sets on your big compound movements
  • Rest 1 – 2 minutes on the isolation exercises
  • Work within the 3 – 9 rep range for compound movements for 2 – 3 sets
  • Work within the 8 – 15 rep range for isolation movements for 2 – 4 sets

Don’t fall into the trap of thinking that you need to do more to hold on to your muscle mass in a calorie deficit.

Remember your goal is to maintain your muscle mass and using a well-structured training plan with a focus on the big compound movements can do this in 3 training sessions a week.

Don’t Use More Than a Moderate Calorie Deficit

The more severe your calorie deficit, the more weight you will lose. 

It sounds great, doesn’t it?

Why not just use a really big deficit and lose all the weight really fast? 

Well, the faster you lose weight, the higher the chance your body will start using your muscle mass as energy. This means you’ll lose fat but you’ll also lose muscle, which is the worst possible thing to happen if you want to retain any strength and look good.

Of course, you need to be in a calorie deficit to lose weight but it should be moderate (20 – 25% below maintenance calories) at the most and closely tracked to ensure you don’t start losing weight fasting than the recommended rate of 1 – 2 lbs per week.

How To Calculate Your Calories For A Moderate Deficit

The easiest way to calculate your calories for weight loss is;

Your bodyweight in lbs x 12 = daily calorie intake

This will set you up at approximately a 20% deficit and you can track your weight from here before determining if you need to make any adjustments.

One thing to be aware of is, as your body fat levels go down so will the number of calories you need to stay in a calorie deficit (8). 

This process is called adaptive thermogenesis and it’s the slowing of your metabolic rate when you’ve been in a prolonged calorie deficit. The greater the calorie deficit and the greater the duration of the deficit the higher this reduction in metabolic rate will be.

However, there’s no need to panic.

At most you’re looking at the slowdown of your weight loss progress over time as your calorie needs change due to this metabolic change combined with your change in weight. (9

As you lose fat and your body weight goes down so will the number of calories you need to maintain your weight, which means the number of calories you can eat and lose weight will also change.

For example, what worked for you at 280 lbs won’t necessarily work for you at 220 lbs as your body’s needs will be different.

Make Sure You’re Eating Enough Protein

We all know that protein is an important part of the diet but this is especially so when trying to maintain muscle mass in a calorie deficit.

  • It fuels protein synthesis which is vital for growth and maintenance of your body
  • It is highly satiating and helps keep you fuller for longer

However, exactly how much you need is often the topic of hot debate and can vary greatly depending who you ask.

That being said most people can agree that your intake should be higher when eating in a calorie deficit to help preserve muscle mass than it does when eating at maintenance or in a calorie surplus.

How Much Is Enough Protein?

Optimal protein intake to build or preserve muscle mass is 0.6 – 1 g per lb of body weight, with the idea of sticking closer to 1 when eating in a calorie deficit and closer to 0.6 when eating in a calorie surplus. (10, 11, 12)

Now going over this recommendation isn’t bad for you but it will impact your intake of fat and carbs which can affect your performance in the gym.

Research (13) shows that glycogen stored in your muscles is the primary fuel source of moderate to intense exercise. Add to this research (14) that shows a sufficient carbohydrate intake that keeps your muscle and liver glycogen stores full can improve workout performance.

Not only this but research shows that when compared a low carbohydrate intake (approx. 220 g per day) against a high carbohydrate intake (approx. 350 g per day) resulted in more strength lost, slower recovery and lower levels of protein synthesis. (15, 16)

Regardless of whether you’re trying to lose fat and preserve muscle mass or gain muscle and minimise fat gain you can begin to see why a moderate to high carbohydrate intake is beneficial for you if you’re strength training regularly.

Obviously, depending on your total daily calorie allowance your carb intake may not be that high but it does go to show that keeping your carbs as high as possible can result in improved performance in the gym which translates to the preservation of muscle mass when in a calorie deficit.

Don’t Overdo Your Cardio

Truth be told you can get lean without doing any cardio at all.

If we refer back to the rules of the energy balance equation, we can see that provide you’re in a calorie deficit you will lose weight regardless of whether or not you’re doing any cardio or not.

However, where cardio can be useful in 2 key ways;

  • Allowing you to eat more food when in a calorie deficit
  • Assisting with the loss of body fat

The question now becomes which type of cardio should you do to get these benefits?

The 2 contenders are;

  1. Low-intensity steady state (LISS)
  2. High-intensity interval training (HIIT).

LISS is characterized by long bouts of walking, jogging or cycling usually around an hour in length to burn calories without taxing the body. Whereas, HIIT is characterized by short bursts of sprinting or other anaerobic activity followed by a period of rest or recovery before being repeated, usually lasting 10 – 30 minutes in total.

What Does The Research Say?

One study (17) comparing the 2 found that high-intensity exercise when compared to steady-state exercise provided “significant reductions in total body fat, subcutaneous leg and trunk fat.”

A review (18) of available HIIT research studies conducted in 2011 found that “Regular HIIE has been shown to significantly increase both aerobic and anaerobic fitness. HIIE also significantly lowers insulin resistance and results in a number of skeletal muscle adaptations that result in enhanced skeletal muscle fat oxidation and improved glucose tolerance.”

Ultimately, whilst HIIT wins out in the research I believe that whichever form of exercise works best for your lifestyle is the best. Maybe that’s a mix of both, maybe it’s none at all. If you can do some HIIT, great. If not then don’t worry as we said before you can get ‘lean’ without using cardio at all.

How Much Is Too Much?

Whatever you choose the key is still not to overdo it.

There is a common phenomenon where people who are trying to lose weight often increase their cardio output and decrease their calories when adaptive thermogenesis begins to kick in. As we’ve already said you don’t need to do any cardio to lose weight provided you’re in a calorie deficit AND your body has a reduced ability to repair itself when in this state.

Considering both of these points it’s advisable to keep the cardio on the lower side and to remember to account for any additional calories burnt when training.

Eat these calories. 

This means 2 – 3 HIIT training sessions a week for 10 – 25 minutes each will be plenty, whilst giving you the benefit of an increased calorie intake for that day plus the fat loss benefits described in the research above.

Alternatively, you could take an hour walk 3 – 4 times a week if you want the extra calories but don’t want to or cannot do the HIIT training.

Ultimately, what I would say is this, don’t do cardio for cardio’s sake. Do it because you enjoy it and want to get the benefits. There’s nothing worse than having to force yourself to go for a run because you think you need to, exercise shouldn’t be associated with negative feelings. Sure, it will hurt sometimes and it should challenge you but it shouldn’t be a chore.

You can always try learning a new sport, doing a team activity or something you find fun.

Additionally, if we put the fat loss to one side for a moment, some form of cardio a couple times a week even if it’s just walking is recommended for general cardiovascular health.

Takeaway Point

Maintaining your muscle mass in a calorie deficit doesn’t need to be a frightful journey full of worry and what ifs.

By following the tactics laid out in this post you can diet with confidence, knowing that you’re going to minimise the amount of muscle you lose if you lose any at all.


  • Train using moderate to heavy weights
  • Reduce your overall training volume & frequency
  • Don’t use more than a moderate calorie deficit
  • Eat enough protein
  • Don’t overdo the cardio