Energy balance myths: Why you can gain fat in a deficit

In my previous article I debunked the myth that you can’t lose fat and build muscle at the same time. You can and most people should. And that’s not the only major misconception surrounding thermodynamics and the energy balance principle.


Myth: Energy balance dictates weight change

If you are in negative energy balance, your body will burn some of its own energy. If you are in positive energy balance, your body will store energy. These are irrefutable conclusions that logically follow from the laws of physics, specifically the first law of thermodynamics.


As a result, being in an energy deficit equals weight loss and being in an energy surplus equals weight gain, right? No doubt you’ll have seen an image like the one below.


Energy balance


In fact, the following image, which is basically the same as the above image but uglier, appears in the respectable journal of Nutrition Reviews from Oxford University Press, the largest in the world.


Energy balance Schoeller 2009


Yet it’s wrong to equate energy balance with weight change. Within the context of a sedentary individual on a balanced diet that only changes his or her energy intake, it is generally correct. However, as a law, which is how most people perceive it, it is false.


The logical error is that not all bodily mass corresponds with stored energy. There are many ways to change your weight while remaining in energy balance.

  • When you go on a ketogenic maintenance diet, you will almost certainly lose body mass without being in a deficit. The lost bodyweight will mostly be water as a result of the lower carbohydrate content of your diet and changes in your body’s electrolyte balance.
  • Foods that cause abdominal bloating and water retention can similarly cause weight gain without a caloric surplus.
  • Not to mention diuretics, the menstrual cycle, drugs, changes in mineral consumption, colon cleanings, creatine, etc.

There are many ways to change your weight long term without changing your body’s amount of stored energy.


Moreover, you can be weight stable while being in a deficit. In my article on the myth that you can’t lose fat and build muscle at the same time, I showed evidence of complete body recomposition in a client and in many scientific studies. You can gain muscle (technically lean body mass, but that’s what most people mean when they say ‘gain muscle’) just as fast as you’re losing fat and a a result your weight will remain the same. This invalidates the idea that energy balance dictates weight change, since evidently being weight stable does not mean you are in energy balance. And being in a deficit does not mean you will lose weight.


And yes, that means the test of finding your ‘maintenance calories’ by seeing at which caloric intake you remain weight stable for 1-2 weeks is not universally correct. I’ve had some clients achieve nearly perfect body recomposition during contest prep. Obviously, their contest prep caloric intake wasn’t their maintenance intake.


And it gets better.


Truth: You can gain weight in a deficit

In true spirit of bodybuilding nihilism, I received the following comment on this site when I explained earlier that energy balance does not dictate weight change.


Nihilism cant gain 3 lb of muscle lose 1 lb of fat


Challenge accepted. In fact, how about we double the odds? Say 6 pounds of lean body mass gain while losing 2 pounds of fat? Ok, you’re on.


Here’s the DXA scan progress of one of my clients. Note how he gained 6.2 lb of muscle while losing 2.1 lb of fat in under a month. Here‘s the full anonymized DXA scan report of his progression.


DXA weight gain in deficit


Don’t believe my data? In my debate about protein requirements in a deficit with Eric Helms, I brought up the Maltais et al. study that showed no difference in body composition changes between protein intakes of 1.1 – 2.1 g/kg. In this study, one group lost 1.1 kg of fat while gaining 1.7 kg of lean body mass. Another group lost 0.9 kg of fat while gaining 1.4 kg of muscle. In other words, both groups gained lean body mass (‘muscle’, as people generally use the term in this context) faster than they lost fat. And these were elderly geezers.


And it gets better still.


Truth: You can lose fat in a surplus

“If someone gained more muscle than he lost fat, he gained weight and thus he was in a caloric surplus by definition.” This was the objection I received from several people when I tried to explain the above earlier. As we saw above, however, this is based on the flawed assumption that energy balance dictates weight change.


This isn’t just a semantic argument where people just have different definitions. The energy balance equation is a mathematical principle.


Change in body energy = Energy intake – energy expenditure


With the metabolizable energy densities of fat and lean body mass from Hall (2008) we can precisely calculate the deficit or surplus someone was in based on that person’s body composition change. Someone who gained 3 pounds of muscle and lost 1 pound of fat must have been in a net energy deficit of 1810 kcal. This is physics, not an opinion.


Taking this a step further, you can lose fat in a surplus(!) Fat loss occurs during a surplus when you gain muscle fast enough to offset the energy your body receives from the fat loss.


However, based on Hall’s calculations you have to gain muscle at a rate 5.2 times as high as your rate of fat loss. In other words, you have to gain 5.2 pounds of muscle for every pound of fat you lose. This is uncommon to the point that I used to say the body would simply not let this occur in a natural lifter. I have also never seen this occur in research in a situation where fat loss was significant.


However, based on an analysis of my own client data, I have to correct myself. It is possible to lose fat in a surplus for a natural lifter. In fact, in my data it occurs even in women.


For example, here’s the DXA progression report of one of my female clients. We only started working together in the last period of this report, so you can ignore the first 2 rows. In our coaching period, she lost 1.3 pounds of fat while gaining 6.8 pounds of lean body mass. That júst puts her in positive energy balance during this period by 170 calories (kcal). Here is the full DXA documentation of her progression. As such, I apologize to everyone whom I told that you can’t realistically lose fat without being in a deficit as a natural lifter. You can.


3 kg muscle gain in deficit


Truth: You can gain fat in a deficit

Following the same logic, you can also gain fat in a deficit. If you lose muscle 5.2 times as fast as you get fat, you gain fat while remaining in a deficit. Unless your weight loss program really sucks though, I should hope this only ever occurs if you stop training, you have a serious medical condition or there are drugs involved.



Energy balance and weight change are almost wholly distinct from each other.

  • Your weight can change without any change in bodily energy storage due to changes in water weight and mass in your digestive tract.
  • You can be weight stable yet be in a deficit. So you can gain muscle and lose fat at the same time.
  • If you’re gaining weight, you may still be in a deficit, because you can gain muscle faster than you lose fat.
  • If you’re losing weight, you may still be in a surplus if you lose a lot of muscle mass.
  • You can lose fat in a surplus if you rapidly gain muscle.
  • You can gain fat in a deficit if you rapidly lose muscle mass.


Interested in more articles like these? Have a look at the Bayesian PT Course.


  1. Mike says:

    Menno – if the individual gets adequate protein in the diet and does some resistance training every week isn’t the rest just a moot point and largely about total calories in/out?

    I’m not sure I agree with you but I really appreciate what you’re getting at – that science can be used as an excuse for dogma.

    I hope one day you develop training materials for non-personal trainers. More or less just aimed at the average dude.

    Keep it up !


    • If you’re referring to my PT Course, many non-personal trainers have taken that. In principle there is no reason why you’d have to be a PT.

      As for the idea that protein and calories are all that matters, that is pure nihilist nonsense.

  2. An-Jey says:

    Careful with your DEXA analysis. IIt’s been reported that 5% variation in fat-free mass hydration can change your DEXA-determined body fat percentage by nearly 3%. This can be an issue when when trying to measure change over time, especially considering that you admit that ketogenic diets change osmolality of the body. I would be interested to see multiple measurements from DEXA scans using different beam types and a program to maintain body composition.

  3. An-Jey says:

    Also, what are the differences between a) 2/15-4/15 vs b) 4/15 & 6/15? the results show inverse correlations. a) fat increased with decrease in lbm b) fat decreased with increase in lbm. Prob better to look at 2/15-6/15 as more representative of trend, which is closer to 1.5kg change in LBM with modest to no change in fat. What are the confidence intervals for the values reported by this type of machine?

  4. Ber says:

    In the case of your client (6.2 lb + muscle mass/ 2.1 – fat mass), what was the caloric deficit?

  5. Michal says:

    Hi Menno,

    in that case, what is your opinion on short cutting/bulking cycles (moving from deficit into surplus) ? Let’s say a 2 weeks bulk followed by a 1 week cut.

    I can’t link the articles right now, but I’ve read it is quite beneficial in terms of muscle hypertrophy. I think Layne Norton is a fan of this approach as well.

    I’d personally say it’s over-complicated bs, however I’ve also seen the biggest gains in the period 2-3 weeks after I came out from a long deficit. Now I am in a surplus for over 2 months, but the muscle (and strenght) growth is much much slower.

  6. Francescop1 says:

    Menno I have found your work up to now to be exceptional. You manage to explain concepts in one blog post that would take others a whole book. I find this one to be a bit misleading however. You seem to equate “lean mass” with muscle mass, when lean mass in the case of a dexa scan, is everything other than fat mass. OK so it is possible to to gain 2kg in bodyweight even though you are on a deficit. Eg when you recarb after a keto diet. This wouldnt be muscle. Some of it could be, even though you are on a deficit, as you explained in a previous article. The dexa results would show this to be 2kg of “lean mass” gained. That hardly qualifies as evidence for what you are saying even though you might be correct in your hypothesis.
    I also have a question for you. Where does this 5.2x muscle to fat loss ratio come from? I read from a reputable source (that also has your picture on it) that it takes about 7500kal to store 1kg of fat and 5500kal to synthesise 1kg of muscle.

    • I explain in the article and Hall’s reference that LBM does not equate with muscle mass, but when we are talking about muscle gains, most people do indeed refer to gains in LBM.

      Similarly, the 5.2 figure is also referenced.

      • Vinay says:

        Hi. So we can’t assume it was all muscle mass gains then?
        Would it be more accurate in the article to state your client gained 6.2 lbs of lean mass as opposed to muscle, because we don’t know that it was all muscle? Or is there a way to know?

        • When people talk about ‘gaining muscle’, they mean lean body mass (or actually fat free mass, since bone content can increase too). If a person gains 5 kg of weight without any fat, we call that a 5 kg increase in muscle mass. Nobody talks about dry muscle mass or protein content or pure contractile tissue, because we just care about volume for aesthetic purposes.

  7. Thomas Howard says:

    I really enjoyed this article partly because I didn’t realise that these sorts of studies/discussions were going on. I’m not a nutritionist but I am a Professor in engineering and I think that you may have overlooked a few things. However, I am ignorant to your area so I may have missed the point but please humor me.

    In your section “Truth: You can gain weight in a deficit” you show a study of your client gaining gaining weight by gaining muscle but losing fat. But where have you shown s/he was in deficit (as Ber also asks)? In my world we always look for the simple explanation and that would be that your client was eating more than you thought – is this not possible?

    Your argument relating your body’s water mass to the ‘gaining weight on a deficit / losing weight on a surplus’ makes total sense! However, you then you seem to move away from that argument and suggest other reasons like displacing fat with muscle and v.v.

    Mass is mass. If your water content is the same and you are in an energy surplus you will put on weight it’s up to you whether it will be in the form of Muscle or Fat. But it does make total sense that you can lose or gain muscle or fat in a deficit or surplus.

    Again thanks for the great article.

    • Gilles Bernard says:


      No it’s not possible that she was eating more, because he is not concluding she was on a deficit from how much she ate, but directly from the energy balance of her body which can be calculated from the lean mass and fat changes from the DEXA. I she was eating more and not on a deficit that would have been reflected on the DEXA scan. For example if she had gained 6.2 lbs of muscle but lost no fat, then she would’ve been in a positive energy balance but as it is, the energy in fat she lots more then offsets the energy in the muscle she gained.

      Mass is mass indeed, but you are making the exact mistake this post was trying to warn you against, and that is not all mass contains the same amount of energy. To take a real life example there is the same amount of mass in 100 grams of say olive oil (mostly fat) and 100 grams of whey powder(mostly protein). Mass is mass indeed, but the first contains significantly more energy.

    • The mathematical proof of how to calculate energy balance is provided in this very article.

      • An-Jey says:

        Menno, as a result of the comments, I had a quick look at the Hall paper and thought about your calculus of energy balance. I must admit that I had never carefully considered the differential energy requirements of tissue types and body composition; only considered intake/expenditure. So, thanks for enlightening me! No wonder ketogenic diets can optimize body recomposition. I found this paper: McClave SA, Snider HL. Dissecting the energy needs of the body. Curr Opin Clin Nutr Metab Care. (2001) 4(2):143-7 which supports your model and was wondering if you knew the values for anabolic synthesis of fat vs muscle?

  8. Dann says:

    Are you willing to share the recomp protocols from which these DXA results were derived?

    I would love to see an article about that from you.

    • Nope, because thousands will copy the program without understanding why that program was optimal for that person. Every client I posted about in this article series had a drastically different program.

  9. Andy says:

    The other thing is, say my maintenance is 3000kcal, and I start eating 3500kcal a day, but my neat increases so that no change in weight occurs, am I still in a surplus? And the same could be said for going into a deficit and metabolism and neat decreasing…. Thoughts and opinions?

  10. Andy says:

    What I was trying to get at is that it’s hard to judge Wether your slightly in a deficit or a surplus, especially when maintenance calories can be quite a large grey area…? I often find I bump calories by 100 a day day, my lifts go up over a few weeks, I gain weight, then my weight begins to fall again but I maintain the extra strength I’ve accumulated

  11. Arevico says:


    Good article. Could you perhaps make the images clickable to a larger version? The DEXA-scan, I can’t read it too well.

    Best regards

  12. Kyle Davey says:

    Really enjoyed this article as well as “Can you gain muscle and lose fat at the same time.” Thank you for doing the research and putting these tools together. I think it will help my clients / coworkers understand the changes going on in their bodies–it has certainly helped me understand them.

    Regarding the DXA scans, I noticed they only separate lean body mass from fat mass. Of course lean mass includes everything other than fat, most notably water. How do you control for fluctuations in water weight on the scans? It’s tough to equate lean mass as muscle mass when water can fluctuate greatly. Is it possible that your clients had different amounts of water weight during the scans, which in turn affected their lean body mass values, which may make it inaccurate to say “you gained 6 pounds of lean mass therefore you gained 6 pounds of muscle?”

    • DXA scans separate bone, fat and misc. lean body mass, which means water goes into the latter category. Within the context of a strength training individual, however, we are concerned with volume, so muscle = lean body mass for all intents and purposes. Also, muscle is actually mostly water in terms of chemical tissue composition. The whole body is, in fact.

  13. Serguei says:

    enjoyed the article, but just want you to clarify if gaining muscle on deficit contradicts with the concurrent relationship between mTOR and AMPk. Does tweaking with nutrition timing solve the problem if you would agree that such problem exists?

    Another question: if we artificially / additionally stimulate muscle growth (putting in some AAS) when in fat-stable state and don’t change anything in training and diet, would we loose fat?

    • The mTOR-AMPK relation is a pathway that explains why you won’t be able to gain muscle at a maximal rate in a deficit, but in real life those are generally activated in alternating fashion, not literally concurrently.

      As for the AAS, it depends on the dosing etc. You have to gain muscle very fast to lose fat in a surplus.

  14. Bogdan Stefan says:

    Menno, my head has a tendency to explode when reading your articles, your stuff is that awesome. And pragmatic.
    I shall ask your opinion on something related to energy balance myths: it is safe to say that recomposition is not only possible, but probable in people with a smart training program, the right atitude and decent nutrition. But is it optimal?
    Say we take an intermediate-almost-advanced lifter. We shall call him Bob. Bob is in decent shape, is a natural lifter, he’s in his mid 20s. Bob is at 14% body fat right now. Bob would like to get to 6%. But Bob would also like to gain some more muscle – 5 lbs minimum, 10 lbs would be better, because Bob would love to compete in a physique show. Bob has 10 months until the show he’s chosen to enrol for. In your opinion, would Bob be better off doing a standard cut, estimating his TDEE from his body fat changes and caloric intake during a 2 week period, subtracting 500-600 kcals from that, and hitting a certain percentage of body fat, say 10%, then bulk – eating a slight surplus of 100 kcals maybe, and then do contest prep to get to 6% – or following another protocol? Your articles always give me the impression that Bob, which in no way, shape or form resembles myself, would benefit from recomping, using a perhaps lower deficit in order to stay sane, for a longer period, and only entering contest prep mode closer to D Day (obviously, if he still has fat to lose).

    • Thanks, Bogdan. Recomping is mostly the result of a successful all-round program, because as you’ve seen, it can occur in both a deficit and a surplus. There is no ‘recomp caloric intake’ (unless you mean weight maintenance).

      • Bogdan Stefan says:

        Indeed it can. What I am asking for is your opinion on what is the faster way to get to a body that is worthy of notice: a) the standard cut, bulk, prep approach or b) recomp?

        • Depends on how you define those strategies. I basically achieve body recomposition by extensive calorie cycling in most of my clients with bulk and cut periods, so my approach differs from all of the conventional methods.

      • Joseph says:

        Hi Menno,

        Very interesting information. I would like to know if you can recomp at calorie maintenance, without a surplus or deficit. Is it possible?


          • Joseph says:

            Thanks a lot. I have read that article, great info. To confirm I have understood correctly, in order to recomp at calorie maintenance, this means that the calories you eat for maintenance goes to all of your daily expenditure, which would not be enough for muscle synthesis. However, since we have energy stired as fat mass, we get the required energy for muscle synthesis from there, which results in simultaneous fat loss and muscle gain (as you have explained).

            Have I understood correctly especially regarding getting the additional required energy from fat mass in order to synthesis muscle when at calorie maintenance? I just need your confirmation on that as I see no other way and I think this was what you conveyed.

            Thanks in advance!

          • Basically, yes. Your body doesn’t see ‘maintenance energy intake’. It just has certain functions it wishes to carry about and a certain amount of available energy from various sources. If the stimulus for muscle growth is there, it will build muscle mass and find the energy for it by catabolizing fat mass if needed.

  15. prabhat sengar says:

    So it seems there are unflavored protein in the market like davisco. they have no enzymes in it. does it make a difference? are there any research that you know of? As i understand there are already enzymes in our body which help digest whole food. so is there any need for enzymes addition in protein powders such as ON. Your thoughts?

  16. Enrique Jackson says:

    Hi Menno,So what would be an ideal carbohydrate deficit for to me help reduce bodyfat, I’m 5’11” at 190 lb\86kg at 48 year old, around 10-15 Body fat your experience and wisdom would greatly be appreicated!

  17. John says:

    > Truth: You can gain fat in a deficit

    While mathematically true, this never happens in the real world except perhaps when fat mass is completely depleted. Every diet study I’ve found shows at least 70% of lost mass as fat mass. Your body isn’t going to prioritize lean mass for energy until there is no more fat mass to oxidize.

  18. Yousef says:

    Hi Menno, I would like your opinion on something. I am currently taking and exercise physiology class the the professor says that 1 set of exercise until failure for a body part is as good or better that multiple sets. He says that in order for your chest muscle to hypertrophy all you need to do is one set until failure, and you don’t need to do different exercise for it with a number of sets!! I think that that is very hard to believe. He showed a study of course demonstrating similar effect of hypertrophy with one set to failure compared to 3 sets to failure at 80% RM, but there are many questions that have not been addressed. What do you think? I would greatly appreciate your opinion on that as I am really shocked by that. I usually do 3-4 different exercises of 3 sets (8-12 reps) for each muscle growing. And now hearing I only need to do one set to failure for each muscle group does not sound right, as I would barely feel that pump with that even if I go to failure.

    In my option I think it may be effective for beginners but not as you adapt to exercise. Looking forward to your general opinion!

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