How can you gain muscle while losing fat & more [interview]

After my 3 recent interviews by Italian groups, next up is a short interview by the Turkish website Agir Saglam. The topics are:
  1. The Bayesian Bodybuilding philosophy
  2. The mechanism of how you can build muscle and lose fat at the same time
  3. Intermittent fasting


You can read the full interview in Turkish here. Below I’ve posted the English original.



First off, what is Bayesian Bodybuilding and how does your Bayesian approach make a difference?
Bayesian Bodybuilding is based on the statistical and logical reasoning principles that were first invented by Thomas Bayes. Basically, this just means it’s a rational approach to bodybuilding. That alone makes it very different from the traditional bro culture that is mostly based on feelings: the pump, the burn, soreness, feeling a muscle, etc.


The Bayesian method is heavily influenced by science, but it takes all forms of data and evidence into account. Furthermore, Bayesian principles specify how to form rational beliefs based on the available information. So where science only concerns itself with the truth about the state of nature, Bayesian reasoning will actually make the step beyond science to form beliefs about the most reasonable practical implementation.


You showed us adding muscle mass in a caloric deficit is achievable. You even state it is not only possible but also should be expected in your article. Briefly, how does this mechanism work?


Indeed, body recomposition is greatly underestimated. In today’s evidence-based fitness culture of ‘nothing matters, nothing works’ most people’s results are so poor that they don’t even believe it’s possible to build muscle mass while losing fat at the same time, yet it occurs literally in dozens if not hundreds of studies (see my article about body recomposition for several references even in advanced lifters). Unless you’re close to your genetic muscular potential or you are close to contest shape, you should be gaining some muscle mass on a cut if your program is optimized.


Now, this has led some people to believe that when I say ‘optimized program’ I have a magic trick up my sleeve that I use with my clients. That is not the case. Many of my clients have years of training experience, they get their protein in, watch their macros and train hard, so all the fundamentals are already there. What I do is tweaking. I optimize everything. Their macros, nutrient timing, exercise order, exercise selection, training volume, the implementation of autoregulation, periodization, sleep and stress levels, their food choices, etc. So successful body recomposition depends on doing everything right. There is no 1 magic trick.


As for the mechanism, first, you have to realize that fat mass (adipose tissue) and muscle mass are distinct compartment in the body. At any time, your body is breaking down and building fat as well as muscle mass. So you are looking at net balances over time. There is no reason why your body can’t modify both lean and fat tissues at the same time. It does so all the time. Denying this would be like saying you can’t heal a fractured bone unless you’re in energy surplus. Or a liver transplant patient will never accept the liver unless the patient is in energy surplus. It’s silly.


It does need substrate to build muscle mass of course. You need building blocks to build a house. Let’s look at what exactly the body needs. Heymsfield et al. (1982) were kind enough to cut up some dead people for us, so I’ve aggregated their results from the healthy control group in the following image. This is the composition of human muscle tissue.


Muscle tissue composition


So what do we need to build muscle mass?

  1. Lots of water (H2O). You can drink plenty of that during a cut, so no problems there.
  2. Several kinds of protein. Again you can eat enough protein on a cut, so no problems here either. For the DNA and RNA we also need nitrogen and phosphate, but those can be derived from dietary protein.
  3. Glycogen and triglycerides. This basically just comes down to energy, because glucose and fat are non-essential nutrients that can be created by the body itself. We need a lot more energy too, because the protein synthesis for the muscle building process is an energy costly process itself.


In short, we need protein, water and energy. Where do we get the energy? Easy. Your body has plenty of that. Let’s take myself in average photoshoot condition at about 87 kg, 6% body fat. People think of this conditioning as ‘having almost no fat’, but the truth is, there’s still plenty of fat even then: 5.2 kg to be exact. If we convert that to metabolizable energy based on the density figures I gave in my article about energy balance myths, the body still has over 49000 calories right there for the taking. That’s plenty to build pounds and pounds of muscle without even taking into account you’re still consuming energy in your diet as well.


So as long as your body has sufficient stimulus to build muscle mass, which it has if your training program is optimized, it has both the means and the will to build muscle mass while simultaneously losing fat. There you go, muscle growth during a cut.


What are your thoughts on using intermittent fasting and macronutrient timing methods for body recomposition?


Nutrient timing is a very extensive topic, so I’ll focus specifically on intermittent fasting (IF). IF used to be a major hype after the rise and fall of Martin Berkhan and it has definite merits. Consistent breakfast skipping – which is how most people think of IF even though it’s just 1 implementation of it – is particularly well suited for certain personality types. This is seen in research as well as my client base.


However, it is not the magic best-method-for-everyone fat loss tool that the cult followers make it out to be.

  • Extending the fast for too long has been shown to impair anabolic signaling in muscle.
  • Fasting across midday has been shown to impair cognitive functioning in some research.
  • Ironically, intermittent fasting zealots tend to name improved insulin sensitivity as a major benefit. This is only true in uncontrolled settings where fasting causes fat loss, which then improves insulin sensitivity. The overall literature on fasting and insulin sensitivity or blood sugar levels is not favorable at all.
In short, IF is a useful tool to have. It is right for certain people in certain situations, but it should not be your one-size-fits-all fat loss method.


  1. Steve says:

    If someone can’t have a sit down breakfast, what would you recommend?

    How soon from waking would you recommend breaking your fast from sleeping?

    Great articles lately Menno!

    • In my experience “can’t” often means “won’t” here and the solution is simply not to fast. There are tons of 5 minute meal options.

      How long to fast depends on gender, your schedule, how advanced you are, etc.

  2. Hemming says:

    If we take you as example with 6% body fat. Won’t it be ‘harder’ for you to use that fat as energy compared to someone who is 25%? I’m thinking that the body would be more keen on holding on to the fat at 6% compared to 25%.

  3. Mike says:


    Will there ever be a more in depth article or interview on IF for those of us who prefer it but would like your feedback?

    Thank you!

  4. Jim B says:

    “-Extending the fast for too long has been shown to impair anabolic signaling in muscle.

    -Fasting across midday has been shown to impair cognitive functioning in some research.”

    Are you able to cite the studies to backup this claim?


    • You should be able to find the first source if you add mTOR or anabolic signaling to the keywords. The second is a relatively recent study with an ~8 hour fast over the lunch period that measured several acute markers.

  5. Gilles Bernard says:

    What do you mean by fasting across midday? Is that fasting past noon?

  6. Victor says:

    Great article. Would eating at maintenance calories following the Katch-Mcardle formula (which ignore fat mass) be a good amount for a recomp?

  7. Tim says:

    I’m a new follower of yours and am benefiting from your recent articles and podcasts, especially how you’re countering the pessimistic/cynical attitudes of many in the fitness world. I’m an intermediate lifter at 11-12% body fat, and my aim is to gain muscle without adding much body fat (to then have to cut). I like IF in the morning, but was wondering if you’d recommend having some protein (e.g., 20-25 grams) in the morning after an evening lift to “feed” protein synthesis. Or, another take on the same question is by approximately what percentage do you think skipping breakfast would impair potential muscle growth in the 36-48 hours after lifting? Or, is my 0.82g/lb of protein (primarily later in the day) sufficiently “feeding” morning protein synthesis? I hope my question makes sense. Thank you!

  8. Larry says:

    Hey Menno, I use IF 4 to 5 days a week. I skip breakfast and eat a normal lunch and have a snack in the later afternoon. I workout after I get off work then have a protein and creatine shack. Wait an hour and have a good dinner.Do you think in any way this hurts the muscle building process?

    PS I am a huge fan of yours!

  9. Joe Petrucci says:

    I’m 190 17% body fat. I have been lifting for decades. I eat very low carbs and plenty of protein I have about 2000 calories a day. Why can’t I get my body fat lower and why can’t I seem to build any more lean body mass?

  10. Hemming says:

    Can you elaborate on how to tweak your diet/macros to optimise muscle building and fat burning? Or is it too interlinked with training and lifestyle?

  11. Vinay says:

    Hi Menno, in your experience with clients and yourself how much does carb vs fat levels in a calorie deficit diet dictate if one can build muscle and lose fat effectively at the same time, assuming protein needs and exercise stimulus and everything else Is there.
    Do lower carbs in the diet in this situation encourage the fat stores to be used as muscle-building fuel?


  12. JC says:

    I am a keen believer of fasting. In the past, people have lived longer by employing fasting techniques. Numerous studies and the recent researches in the field of Epigenetics have shown tremendous potential of fasting and how it can change certain gene expressions including activation of genes that are responsible of retardation of tumours and cancer cells. How do you associate fasting with a common man who’s not looking to be a bodybuilder but to stay fit and healthy.

  13. matt says:

    Interesting topic.. i’ve read quite a few about this lose fat and build muscle at the same time articles and i still have 1 question. Just one. Calorie intake? 10% deficit? Maintenance? Surplus?

  14. ?rfan tekinkus says:

    Hi menno,
    We’ll ketogenic diet fed with how high-carbohydrate , ketogenic and burn fat while dieting
    and also how should I set if I want to see a good muscle development calories

  15. Tyler says:

    Hey Menno, so based on this it’s a totally viable option to eat at maintenance calories while progressing in the gym, using your fat to fuel muscular adaptations, allowing for slow gradual improvements in body composition. What would basically be effected is the rate of body comp improvements, it’ll just take longer to see the same improvements in muscle mass recomping than it would by doing proper bulks and cuts. So for those who are generally satisfied with their current physique and don’t want to bulk and then cut a good option for them is to just eat at maintenance and make slow and steady improvements in body composition. It’s not optimal but it’s a viable option for certain people in certain situations. Especially lifters have a third option besides bulking and then cutting.

  16. Kevin says:

    Hey Menno,

    In the interview you said this about intermittent fasting:

    “Consistent breakfast skipping – which is how most people think of IF even though it’s just 1 implementation of it – is particularly well suited for CERTAIN PERSONALITY TYPES.”

    What certain personality types are you referring to? If you can, can you also link to research? Thanks!

  17. Rohan says:

    Thanks for these great I understood from other article on protein intake it is sufficient to take 0.68 to around 0.82 protein/pound then how can we design macros for losing fats and building muscles at the same time..what would be carbs and fat%? I am underweight but i have 19.5% body fat

Leave a Comment