Can you build muscle and lose fat at the same time?

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Photo by Jakob Owens on Unsplash

Short answer: Yes, you can build muscle and lose fat simultaneously.

Longer answer: It’s a bit more complicated and depends on a lot of individual factors –namely body composition, training status, genetics, insulin sensitivity, hormonal milieu, and your definition of “at the same time”.

Before we delve deeper into the discussion, there is one thing I want to clarify.

Possibility ≠ Probability

This is important for perspective because I will discuss both –the possibility (theoretical viewpoint) and the probability (practical viewpoint). So this article will answer the questions “Is it possible?” and “How?”. But most importantly: “Does it make sense for you?”.


… theoretically kinda could work ≠ optimal practical pursuit.

Now, I present to you, the longest answer known to mankind to the question if you can build muscle and lose fat at the same time.

This is a comprehensive article. If you don’t care to read my explanations, you lazy spud, skip to the last part. There’s a flow chart. And some practical tips.

Simultaneous Muscle Gain and Fat Loss? Defining “At The Same Time”

I mean, what do we mean by that? At the exact same moment in time? In the course of a minute? Hours? Days? Weeks or months, even?

On a macro level, you could cycle between overfeeding (gain muscle and fat) and underfeeding (maintain muscle and lose more fat than you’ve gained during overfeeding) for a given time period and you’ve successfully gained muscle and lost fat at the same time (hours, days, weeks, months).

On a micro level, you’d think that you burn fat and that supplies the energy for the concomitant muscle growth –shunting the calories at the (almost exact) same time.

All the anecdotes and (case) studies generally refer to a period of several weeks up to a few months when they mean “at the same time”. The mechanisms could be either located at the macro level, the micro level, or a mix of both.

It’s more of a theoretical question. And I can, honestly, not give you a clear cut answer. Because, well, I have no idea. Ask someone smarter.

But in reality, there’s no need to quibble. Who cares if it happens at the exact same point in time, over the course of a day or weeks, or both? Well… I do. But most of you probably don’t. I think we can all agree: As long as the net result at the end of the month is more muscle and less fat, that’s pretty cool for everybody.

I’ve only mentioned this because there are a lot of bros who say that it’s impossible to build muscle and lose fat at the same time because of thermodynamics. You need to be in a caloric surplus to gain muscle (and fat). You need to be in a deficit to lose fat (and muscle). Another reason they give is that there can’t be concurrent catabolism and anabolism in the body.


Not only are these insufficient answers but their absolute assumptions are also wrong. Later, you’re going to see why.

The combination of all the information you need (or better: want) just one click away and the Dunning-Kruger effect…

Anyhow, let’s continue.

Muscle, Fat and Nutrient Partitioning

Although the appearance of some hapless individuals suggests otherwise, we’re not one big clump of uniform tissue.

Muscle and fat are two different functional compartments to which calories get distributed, at least somewhat, independently.

Anecdotally, you can see that in overweight and untrained people who become lean and muscular over time. Apparently, these two compartments didn’t react and do the same with calories. And that is true.

Scientifically, you can express the energy partitioning parameter as the P-ratio (Dugdale et al. 1977)

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In words:

The P-ratio defines the fraction of an energy imbalance accounted for by changes of the body’s protein reserves.” — Hall. 2007

Wait… What?

Lyle McDonald simplified it by saying that “it represents the amount of protein that is either gained (or lost) during over (or under) feeding.”

For our purposes of building muscle and losing fat at the same time, let’s say that the P-ratio expresses the lean tissue : fat tissue calorie distribution ratio.

But now to the more important question. What controls the P-ratio and the energy partitioning?

This is going to suck.

Most of it is largely out of your control –i. e. genetics and hormones (no, your “raise/ lower your *insert hormone here* by 1000% in 30 days” program isn’t working).

But there’s a silver lining.

You can, Lyle estimates, control 15–20% with eating or training.

Of course, this number is not set in stone and depends on a host of factors.

Further important but more modifiable factors are body fat and insulin sensitivity. Which both tie back to eating and training.

For now, just keep in mind that it’s possible.

A Brief Digression: Nutrient Partitioners

There are some other things you can do to influence nutrient partitioning. Later in the article, we’re going to look at them in more detail.

But for now: Do you know the best nutrient partitioner ever?

The best nutrient partitioner is …drumroll please… steroids. They overwrite everything. Don’t do it though :).

Do you also know what’s the worst nutrient partitioner ever?

The worst nutrient partitioner is …drumroll please… a Nutrient Partitioner ­–the supplement.

Not only is this quite hilarious but they can often result in a complete backfire.

Take Berberine for example –a popular and widely used ingredient in Nutrient Partitioners. Berberine activates AMPK. Supplement companies claim that this improves insulin sensitivity and nutrient uptake in the muscle cells. That’s correct.

But since it’s not a local effect, Berberine also improves insulin sensitivity and nutrient uptake in the fat cells. That’s problem #1. But of course, they don’t tell you that.

Buckle up, it gets even worse.

AMPK inherently suppresses mTOR and muscle hypertrophy. That’s problem #2.

Strength training can counter-act the AMPK activation in muscle cells. But since AMPK is Berberine’s molecular target, the Nutrient Partitioner ends up having no effect at all.

Oh, wait. It still works –but only in fat cells!

In this scenario, Berberine has no effect in muscle cells but increases insulin sensitivity and nutrient absorption in fat cells. You’ve potentially worsened your p-ratio. And that’s problem #3.

I’ll go out on a limb here and guess that this is the exact opposite goal of somebody who is trying to recomp. Unless you want to recomp inversa.

Berberine is actually a promising anti-inflammatory and anti-diabetic agent. But therapeutic doses are much higher (and have side effects) than the vanishingly small amounts which are ought to be found in supplements.

I don’t want to pull a straw-man argument here and say that every Nutrient Partitioner sucks because Berberine doesn’t work for recomp. But, more often than not, they are not a good investment with a terrible cost-benefit assessment. As a rule of thumb: If a pill improves insulin sensitivity it does so, more often than not, in both muscle cells and fat cells.

Just use your muscle cells and they will be more willing to absorb nutrients.

Thermodynamics Do Not Make It Impossible to Build Muscle and Lose Fat at the Same Time

You know what they also don’t disallow?

  • Losing muscle in a surplus
  • Losing fat in a surplus
  • Gaining muscle in a deficit
  • Gaining fat in a deficit

The first law of thermodynamics, the conservation of energy, is a law of energy balance. But it can’t, and doesn’t even want to, predict calorie partitioning, let alone the tissue-specific metabolic and hormonal situation. It also doesn’t dictate weight change (*Don’t freak out. I’m not saying that CICO is B.S.; e. g. 1) an isocaloric ketogenic diet leads to lower bodyweight through glycogen/water loss, 2) GI-tract can be full or empty, 3) body recomposition in a deficit can keep weight relatively stable [FM↓ MM↑])

It states that energy can neither be created nor destroyed. Energy has to go somewhere and doesn’t just disappear. An energy surplus will lead to storage and a deficit will result in energy leaving the body. You need the energy to build muscle or fat cells and you release it once you break them down.

That’s cool and all true.

But, again, it describes the net-effect on a whole body level and not the respective contributions of either muscle or fat –i. e. it doesn’t predict the partitioning. The distribution ratio of calories between fat and muscle could be 50:50, 40:60, 60:40, etc.

Yes, I know, some of the bullet points seem very unlikely. But they are theoretically possible. However, like I’ve said possibility ≠ probability. And you would get some ludicrous numbers if you’d try to estimate how fast you’d have to build muscle if you wanted to lose fat in a surplus. But it can be calculated (Hall’s formula).

I’m quibbling again (damnit) but I just wanted to make clear that you can’t refute the idea by saying “Yeah thermodynamics, so no.”

Physiologically unlikely, I can live (and argue) with that, but physically impossible, I can not.

Thermodynamics do not rule out the possibility to build muscle and lose fat at the same time. Stop using that argument.

Roughly speaking, your body needs adequate amounts of stimuli, protein, water and energy to build muscle tissue. If you supply your body with the first three things, it’ll only need energy and this energy can theoretically be gained from burning your own body fat.

But, of course, this requires a bit more of a nuanced approach.

Who Can and Who Can’t Build Muscle and Lose Fat at the Same Time?

Theory lesson: When you’re in a calorie deficit anabolic processes get down-regulated and catabolic processes get up-regulated. This, in turn, means that a given anabolic stimulus will have somewhat less of an effect.

For you nerds out there, here’s a comprehensive graphic.

[caption id=”attachment_7549" align=”aligncenter” width=”540"]

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(Jo et al. 2016)[/caption]

The “globality” of this hypo-anabolism (i. e. different tissues, different energy balances), however, further depends on the magnitude of the deficit, strength training, and how much body fat (i. e. energy) you have to spare. Still, you will not have the ability to be as “anabolic” as if you ate in a surplus.

So, it’s definitely not an optimal environment for growth.

But there are three demographics who are somewhat almost predisposed to gain muscle and lose fat at the same time.

  • Overweight beginners: They have a low amount of muscle mass and a high potential for newbie gains. They require little stimulus for a substantial effect. They have a high body fat percentage, i. e. plenty of energy to spare and invest. They are often systemically insulin resistant, i. e. their cells –especially fat cells– “don’t want” more energy. Through strength training they send a potent growth stimulus and, most importantly, better their insulin sensitivity and nutrient uptake locally –i. e. in muscle cells only (contraction-mediated GLUT-4 translocation etc.). So, the fat cells remain insulin resistant and push calories away while the muscle cells are more insulin sensitive, receive a potent growth stimulus and happily welcome all the calories. Long-term results: Body-recomposition. More muscle, less fat.
  • Athletes returning from a layoff: They lost muscle mass that was previously there. Bonus points are given to those who gained a substantial amount of body fat and got more insulin resistant. They have an easy time to rebuild that muscle mass (i. e. satellite cells and “muscle memory effect”) and probably have plenty of fat energy to spare and invest.
  • Steroid users: Again. Steroids overwrite physiology. Don’t trust the juiced up meathead who says you’d just have to work harder and believe in yourself.

The more you move away from either one of these stages, the harder it’s going to get to gain muscle and lose fat at the same time.

To put it into a parable: The leaner and more muscular you are and the fewer steroids you use, the less likely you are to gain muscle and lose fat at the same time. And vice versa.

“But I’m a fairly lean and muscular guy. Is it impossible for me to recomp?”

Impossible? Probably not. But harder. Much, much harder.

The third and, I promise, last time: possibility ≠ probability.

In our enthusiasm for the holy grail of fitness, we often tend to forget that 1) building muscle is hard work, and 2) losing fat is hard work. And 3) trying to do both at once makes none of them easier.´

But what does the body of evidence suggest? We want some studies!

Building Muscle and Losing Fat ­– What Do the Data Say?

There are studies showing that body recomposition is possible in almost every demographic –even in people where we wouldn’t expect recomp. Male, female, youngster, oldies, healthy, unhealthy, obese, lean, elite athletes, gym bros, couch potatoes, John and Jane Does; all managed to achieve body recomposition (Treuth et al. 1985; Wallace et al. 1997; Dolezal et al. 1998; Demling et al. 2000; Nindl et al. 2000; Iglay et al. 2007; Josse et al. 2010; Garthe et al. 2011; Josse et al. 2012; Paoli et al. 2012; Longland et al. 2016; MacKenzie-Shalders et al. 2016; Moro et al. 2016; Hulmi et al. 2017).

Bonus point:

  • The training and nutrition protocols (protein intake etc.) are often, well, let’s say suboptimal. And they still achieved body recomposition.

On the other hand, however, there are studies which show negative results in almost every demographic –even in people where we would expect recomp. Please just trust me on this one. There are a lot of studies which show fat loss with either LBM maintenance or LBM loss. Don’t make me cite them all.

You can cherry-pick your way through the evidence and make your case. As always.

Sobering points:

  • Most of the studies were done on overweight and/or untrained. And even here we have mixed results.
  • Elite athletes usually aren’t bodybuilders. There’s still potential for muscle growth. And elite athletes often use the kind of Nutrient Partitioner that actually works (i. e. steroids).
  • The so-called “lean and trained subjects” most often do not represent the actual lean and trained bodybuilding population.

All things considered, I think that your ability to build muscle and lose fat at the same time highly depends on your individual genetics and the experiences you’ve made so far.

One shouldn’t say: “Well, you can’t build muscle and lose fat at the same time because I found a study that matched your demographic which shows that you can’t.” The other way around also doesn’t work.

Reality check: Have you always had a hard time to manage muscle gain and/or fat loss? Did only bulking and cutting phases do the trick for you? If so, then maybe don’t even try it. However, if you feel like that’s your thing and what you’ve always done, go for it. But the more advanced in terms of training status and body composition you become, the more it will slow down and eventually come to a halt. Just remember that 1) neither muscle gain nor fat loss will be as high and quick as if you ate in a surplus or a deficit, respectively. 2) The rates of muscle gain and fat loss will be very different (FL fast like a tortoise, MG slow at a snail’s pace). And 3) it’s harder than focusing on one goal at a time.

Can You Build Muscle and Lose Fat at the Same Time? A Flow Chart

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This flow chart isn’t perfect at all and is by no means intended to be completely comprehensive. It simply serves as an illustration of the things that I’ve discussed so far. Some perhaps important factors like age and gender are left out because most of our readers are young to middle-aged male.
*Beginner/Advanced refers to training status and muscle mass.
*Meh means: You can try it. You might succeed. You might fail miserably.
*Nope doesn’t mean impossible. I’m trying to suggest that you will probably benefit a lot more from focusing on one goal at once.

While I’m explaining and justifying everything, I realize that this graphic is very far from perfect :) …

How to build muscle and lose fat at the same time

I’ve babbled so much. Let me give you some actionable advice, if you want to try it.

#1 Count calories if you must.

Mandatory. Keep your calories near maintenance. A moderate deficit at most. Remember, you still want to build muscle. The magnitude of the deficit depends on your body fat status. The more you carry around, the higher it can –and should– be. If you suck at estimating your caloric input (experience), count them. If you’re like me and have a solid built-in energy sensor, you don’t have to. But this makes recomp harder, difficult to estimate, and is probably going to take a much longer time.

#2 Cycle between strategic periods of undereating and overeating.

Helpful. The Ultimate Diet 2.0 by Lyle McDonald, intermittent fasting protocols (e. g. Leangains), The Anabolic Diet by Mauro Di Pasquale, Carb Back-Loading by John Kiefer, The Warior Diet by Ori Hofmekler are all good places to start.

Pick your poison or just ask us directly :) .

#3 Train in the evening. Eat the majority of calories after your workout.

Optional but probably helpful. Point 1) Calorie control is easier because you have less time to eat. Point 2) You’re more insulin resistant later in the day. Strength training improves insulin sensitivity in muscle but not so much in fat. Result: Better partitioning. That’s the idea, at least –your muscle is more receptive to nutrients now (GLUT4, glycogen synthase, FAT/CD36, amino acid transporters, IGF-1-receptor, local metabolic growth factors etc.).

#3.1 Train fasted.

Optional. See reasoning in my article about intermittent fasting and performance.

#4 More strength training, less cardio.

Probably mandatory. Depends on your current routine. In a deficit there’s more AMPK baseline activation and AMPK suppresses mTOR which we need for stimulating muscle protein synthesis. Roughly, strength training activates mTOR and cardio AMPK. So, more strength training and less cardio. Instead of cardio, do sprints. Strength training increases nutrient absorption and insulin sensitivity locally in the muscle (see #3). Train hard. Don’t allow a drop in performance. If you get weaker then you’re probably not building muscle (strength ≠ muscle growth but it’s a good proxy) and your deficit may be too high. Recalibrate.

#5 Up your protein intake.

Critical. Because 1) you use more amino acids for energy (gluconeogenesis) in a deficit, 2) you need to bump up your lower-baseline anabolic machinery, and 3) you need the building blocks for protein synthesis. Btw.: You need all the essential amino acids (EAA) for muscle growth. BCAAs are a waste of your money.

#6 Control your hormones…

… to the extent that it’s possible. Most of it is genetically set. But there are some sensible things you can do and obvious faux pas you can avoid to prevent your hormonal levels from going south. For example, we’re looking at testosterone (keep high), cortisol (keep low; at least don’t have chronically elevated cortisol levels), thyroid hormones (maintain), and leptin (deserves an own article).

Basic measures: Eat protein, carbs, and fat. Fear neither. Don’t eat too little. Do re-feeds. Avoid, at least manage, psychological stress. Meditation is an option. Get enough fish-oil, vitamin C, D, and B-vitamins, magnesium, zinc, selenium, and iodine. While you’re at it, get enough of every vitamin and mineral. Get enough restful sleep. Be sensible.

#7 Don’t use Nutrient Partitioners

If you don’t know why by now, you didn’t read the article. You lazy bastard, you.

How Do Beasts by Nature Build Muscle and Lose Fat at the Same Time?

Honestly, I don’t think I’m recomping very much anymore –if I did, then at a painfully slow rate. But I have remained at the same body fat percentage for over 8 years now without too many fluctuations and got stronger and more muscular over these years. Nowadays, I still get stronger but, again, at a crippled snail’s pace.

I’ve never counted calories in my life. I could have just as well unconsciously cycled between periods of higher calorie intake and lower calorie intake giving me the impression of building muscle and losing fat at the same time.

Till and I usually train fasted for (non-dogmatic) reasons beyond the scope of this article. Ask us if you’re interested J. Anyway, I think it can help some folks who are trying to recomp. I explain the rationale behind this in my article about intermittent fasting and performance.

Feel free to give it a shot. Maybe it’ll work for you. Remember: It isn’t impossible.

But: possibility ≠ probability.

Fourth time. Oops. I lied and didn’t keep my promise.

I never do :D

Cheers :P

This article was brought to you by the lovely Leon Brouwer, co-founder and author at Beasts by Nature. In future, this channel will include more of his work. I hope you enjoyed it (if yes, leave him a clap :P) , Till

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Further recommended readings:

References are hyperlinked. If there’s a broken link, let us know.

YouTube content creator, nomad, and part-time philosopher and @bullverine on Instagram.

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