Muscle growth sans carbs

1.  net muscle growth = synthesis – breakdown

2.  need =/= optimization

3.  #context


muscle sans carbs


I’m totally cool with keto, honestly!  but still don’t really like seeing stuff like the above graphic and people interpreting it to mean “KETO IS MUSCLE-SPARING.”



Keto isn’t muscle-sparing; the above graphic says nothing about net muscle growth.  For that, you’d need to data on muscle protein breakdown, and preferably, an empirical measurement of actual hypertrophy.  Synthesis is only half of the picture… and it doesn’t always favor keto… #context

For example, “Cumulative urinary nitrogen excretion was significantly greater and cumulative nitrogen balance significantly more negative, during treatment with the ketogenic than with the nonketogenic diet… Whole-body rates of leucine oxidation were significantly higher during treatment with the ketogenic than with the nonketogenic diet…” (Vazquez and Saimak, 1992).

And this: “Four hundred kcal carbohydrate per day had a greater protein-sparing effect than 400 kcal fat per day in obese women… We conclude that carbohydrate is necessary to spare tissue protein” (Bell et al., 1969).



As far as skeletal muscle growth is concerned, carbs and protein are more anabolic than dietary fat.  I won’t argue that carb-restriction isn’t effective for fat loss in obese patients, especially if insulin resistance is present, because that simply isn’t true…

although even this isn’t always the case (from Yang and Van Itallie, 1976):


van itallie


Insulin is largely thought to reduce protein breakdown more so than promote muscle synthesis (eg, Gelfand and Barrett, 1987Hillier et al., 1998, and Fukagawa et al., 1985).   And you get way more insulin with carbs and protein (but really just carbs) than with dietary fat.  Yes, there are some studies showing decent insulin spikes with whey, so the gym-bro’s might be able to slam protein shakes to get some of this benefit.


And none of these studies even address what I consider to be more important variables: SLEEP and CIRCADIAN RHYTHMS.



Can you build muscle on a low carb diet?  Yes.

Do you need carbs to build muscle?  No.


need =/= optimization

Sleep well, eat protein-rich foods, and perform resistance exercise = build muscle… but you’d probably build more muscle by swapping out some dietary fat for carbs (assuming isonitrogenous & isocaloric diets).  That’s partly why things like the Targeted Ketogenic Diet and Carb Nite were developed.

Priorities?  #context?  Yes and yes (P<0.05).

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  • George

    “Four hundred kcal carbohydrate per day had a greater protein-sparing effect than 400 kcal fat per day in obese women… We conclude that carbohydrate is necessary to spare tissue protein”

    This is a very low calorie diet;, and so was the other study cited; the metabolic adjustments to caloric restriction are confounding the issue.

    Newburgh and Marsh found that nitrogen balance was attainable at 0.66 g/Kg protein per day on a high fat, very low carb diet. Woodyatt takes this finding and nicely describes the importance of an adequate fat intake to the inhibition of proteolysis at conditions of low fat mass here.

    Looking for an explanation for Woodyatt’s exposition that the rate of fat oxidation is constant whether fat is fed or fasted, I found that somatostatin 28 (and not insulin) rises in response to fat feeding, inhibits lipolysis, and has a clinically significant protein sparing effect.

    Yes, if you weren’t eating enough fat, the effect of insulin in response to carbs might give a superior protein-sparing boost. But are bros pumping iron on keto restricting calories? Seems unlikely. They have low fat mass, so can’t be dropping fat calories if they want to retain protein.

    • Richard Garcia

      “But are bros pumping iron on keto restricting calories? Seems unlikely.”

      I know quite a few that do. If anything, keto seems more popular for cutting than bulking.

      • George

        I don’t know much about this, but if cutting = cutting fat for definition (without losing muscle) and bulking = increasing muscle and muscle glycogen stores for size, that makes sense.

        • insulin decreases muscle protein breakdown
          (ignoring this was one of the flaws in people’s interpretation of the infographic, imo)

          • rs711

            the infographic is summarizing a dietary intervention on muscle protein synthesis…it also “ignores” somatostatin 28, GH & many of other hormonal variables, so what does it matter what insulin does by its lonesome? It’s a surrogate marker, not what we’re ultimately going after (MPS).

          • changes in SST, GH, insulin (indirect evidence)


            studies on actual muscle protein, leucine oxidation, nitrogen balance, etc. by Vazquez, Bell, Yang, et al. (direct evidence)

            you choose!

          • George

            “Proteolysis is enhanced as a result of lack of insulin in muscle, providing a supply of glucogenic and ketogenic amino acids. The glucogenic amino acids (alanine, arginine, etc.) pass to the liver to fuel the furnace of gluconeogenesis. In addition, lack of insulin at the liver activates the enzymes of gluconeogenesis.”

            “With subcutaneous or intravenous administration of insulin, the concentration in the portal circulation will always be less than in the systemic circulation. This is a reversal of the normal situation. Good glycaemic control thus invariably results in peripheral hyperinsulinaemia. Hence lipolysis and proteolysis are slightly ‘over?controlled’ (protein synthesis is normal—insulin?independent and regulated by growth hormone—but protein breakdown is reduced as a result of the ‘chalonic’ action of peripheral hyperinsulinaemia).”


          • deb

            So insulin decreases autophagy then?

        • rs711

 “DEXA provides a measure of lean soft tissue (LST), and the original notion that LST hydration is constant is not correct. Rather, LST hydration varies as a function of extra- and intracellular water distribution.”

          1g glycogen comes with 3-4g of water iirc, so glycogen stores don’t, strictly speaking, count towards bulking (volume & aesthetics aside).

          Further on in that same study, the author reiterates your point about hypocaloric diets George “Vazquez and Adibi reported that proteolysis, as measured by leucine turnover rate and urinary excretion of 3-methylhistidine, was not significantly different between isocaloric VLCARB and non-ketogenic diet [17]. However, this study is not relevant to “normal” weight loss diets, because their subjects consumed only 600 kcal and 8 g of nitrogen per day. Such a semi-starvation diet will lead to increased muscle protein catabolism no matter what the subjects eat.”

      • “keto seems more popular for cutting than bulking”

        Probably more effective, too.

    • rs711

      The points you raise George speak to the manner in which I interpreted the infographic; LCHF/keto diets are ‘muscle sparing’ but that doesn’t necessarily mean they are optimal for muscle growth. That would require a different experiment than the one upon which the infographic is based.

      The point you make about somatostatin 28, to me, alludes to the fact that insulin (obviously) works in concert with other hormones, and with (+ or -) sensitive pathways downstream, within a cell; circulating insulin levels have been easy to measure for a while now so we tend to hyperfocus on it at the expense of the mechanisms it engenders downstream. Baby steps… 🙂

      • George

        I interpret the data in this fashion – if fat has a protein-sparing effect, and if lipolysis is kept in balance when fat is ingested, and yet there is no rise in insulin following fat feeding, there must be an alternative regulatory system for this nutrient.
        This system is clearly under-written by basal insulin, it is dangerously unstable without it, but it is not insulin that is doing the things that insulin does when carbohydrate is fed. i.e. rising in the circulation to reduce the release of competing substrates, and the reason may be that insulin primarily controls gluconeogenesis and there is no need to reduce GNG when fat is fed.

    • “Newburgh and Marsh found that nitrogen balance was attainable at 0.66 g/Kg protein per day on a high fat, very low carb diet.”

      nitrogen balance in the high carb control group?
      if they didn’t include this control group, hard to interpret this as “keto is muscle-sparing”

  • rs711

    Hi Bill,

    Interesting post.

    One remark: “And you get way more insulin with carbs and protein (but really just carbs) than with dietary fat.” <== This is true.
    However, circulating insulin is only a partial picture of insulin's effect, which is what we really care about. We'd want to know the #context in which that circulating insulin level is working within (sensitivity being but 1 factor, for e.g.).

    This point was reiterated by David Ludwig recently, whereby circulating levels are a snapshot and not the dynamic 'movie' picture we really want to know about insulin.

    I think that certain carbs can increase appetite and thus increase total kcal intake which *may* be necessary for someone finding it difficult to eat sufficient kcals in a (hyper)bulking phase. It's an interesting open question to me.

    FWIW I agree that SLEEP/CIRCADIAN is *probably* more important than macronutrients for hypertrophy (leaving aside obvious things like protein deficient and nutrient deficient diets, obviously).

    • Ian Rambo

      I’ve done 4 Carb refeed days in 12mths just fipor experimental purposes, so unlikely to have made much difference to LBM. The bulk of the time was spent in strict Ketosis while resistance training 5 days a week, 2 hours. Carbs <50g, Protein 130g, Fat 190. Weight increased from 69kg to 72.5kg with the same body fat 10-12%. Tape measurements and before /after photo comparisons confirm LBM increase, it's obvious. No TRT, or other chems and i'm 62yo. Keto Adapted 2 years, lifting 1 year. Always abide by Good sleep patterns and Circadian Rhythms. That is enough proof for me carbs arn't needed if protein is optimal and calories are 10% above maintenance.

  • By saying “keto is muscle-sparing,” the implication is “keto is more muscle-sparing than a high carb diet.” For that, you need a control group (high carb).

    And the studies cited above suggest this isn’t true.

    • George

      Perhaps keto only needs to be as muscle-sparing as a high-carb diet, which is known to be muscle sparing through the effect of insulin.
      My examples from
      Marsh PL, Newburgh LH, Holly LE. The nitrogen requirement for maintenance in diabetes mellitus. Arch Intern Med (Chic). 1922;29(1):97-130.
      and Woodyatt 1921 weren’t controlled, because they involved subjects with decompensated diabetes who had runaway proteolysis unless they followed what was (in essence) a keto diet. Nitrogen balance at 0.66 g/Kg protein is best regarded as a “constant” in this group and compared with the similar “constant” for this in a normal subjects on a high-carb diet. The median for this “constant” derived from meta-analysis is currently 0.65 g/Kg.
      Pretty good work by Marsh, Newburgh and Holly in both normalising proteolysis without insulin, and in measuring normal nitrogen balance, 90 years ago.

      Insulin is like a superstar who also plays in the backing band on his friends’ records. Some people only rate these because Insulin plays on them, but that’s not why they’re great.

      • George

        Correction; I misremembered Marsh, Newburgh and Holly; the 0.66 g/Kg/diem figure comes from the other Newburgh diet papers and was used as a baseline average figure, to be adjusted up or down as needed. Marsh 1922 in fact says

        “Five of thirteen of the diabetic patients excreted less than the average of the normals, and three of fourteen of the normals excreted more than the average of the diabetics. The fact remains, however, that the average of the diabetics was higher than the average of the normals, and four of the diabetics eliminated more nitrogen than the highest of the normals.”

        “Weintraud 22 demonstrated conclusively as long ago as 1893 that fat fed to the diabetic subject was very powerful in saving his protein.
        An example of his experiments is shown in Table 17.”

        Weintraub’s Table 18 shows that as more fat is fed to diabetics, (up to 272g) a greater % of it is digested (almost 99%, vs 89% of a smaller amount). Interesting.

        “Dunlop doubted the value of fat in sparing protein in diabetes, as demonstrated by Weintraud and quoted in support of his doubt
        the experiment of Karsëner who brought himself into nitrogenous equilibrium on a diet of protein and carbohydrate, and found that he
        was no longer able to maintain this equilibrium when he replaced a large part of the carbohydrate with the caloric equivalent of fat.

        The experiment of Karsëner merely confirms the greater efficiency of carbohydrate than fat in sparing protein.”

        There I think we have it. Carbohydrate spares protein more efficiently than fat does. (Karsener I presume was not diabetic.) But fat spares protein; quite well enough for the diabetic, and well enough for anyone who wants to take advantage of some effect of carbohydrate restriction to know they won’t lose muscle doing so.

        Sorry for misleading everyone.

        • cool…
          Although physiologically, it still seems a bit odd to say dietary fat is muscle-sparing (and I don’t think it’s really correct).

          priorities: if your goal is primarily fat loss, LC is fine. If goal is muscle building, probably better off with some carb…
          and diabetes is a different context entirely.

  • This Old Housewife

    I just forwarded this post to Jimmy Moore. He completed a 30-day fast a few days ago, and testing afterward showed he lost 10 lbs. of muscle. I think he lost 23 lbs. total, but am not sure of this number–I know it was 20-SOMETHING lbs. lost.

    So it sounds like the CICO method works, only you have to be very discriminating with the calories that go IN. But this is a housewife talking, and I could be very wrong here (like misinterpretation–prone to that).

    I just had a birthday last week, and I celebrated the fact that I’m now the same size I was in high school. Hubby has even made progress, and has lost about the same amount of weight as I have (but has more to go). At least now he’s off most supplements (including chromium), and short-term fasting has dropped his LP-IR to half what it once was. He’s also now in Pattern A territory. Things are definitely getting better for him–took long enough!

    Last month, he had to have new belts made, because his old ones had no more room to punch holes and still maintain leather integrity (according to the leather shop). We even had to buy smaller pants for him.

    • Ian Rambo

      Jimmy didn’t lift weights during the fast, if he had, the muscle loss would most likely have been much less, more so if he was a resistance trained individual which he isn’t.

      • Beta Hydroxybutyrate

        The muscle loss was mainly from the trunk. His arms actually gained a little and his legs lost a little. There’s something strange about that.

  • Somatostatin 28 on muscle is starting to seem sort of like ASP on adipose…

  • Thomas Hemming Larsen

    Good posts pointing out some of the pitfalls with just looking at an info graphic. I really like your unbiased approach to nutrition.

    • thanks, Thomas!

      • Thomas Hemming Larsen

        One thing though, why have you not written about all the latest protein studies?! 🙂 The research from Stu Phillips and Jose Antonio would be right up your alley 🙂

  • Great post Bill!

  • palo

    Dr. Lagakos what is your opinion of Dr.Mario Pasquales’ Anabolic Diet for bodybuilders. At least one meal and up to 2 days during the weekend high carb and the rest of the week 30g. or less of carbs.

    • nothing magical, so, if it works for you… ymmv.
      Also depends on goals, context, etc.

  • Eddie

    A few days ago, Mark Sisson spoke about another variable, post workout HGH, he mentioned that PWO insulin could blunt it by consuming carbs post workout. (

    I found an article that mentioned it:

    and it cited this study:

    How much impact do you think PWO HGH, is providing to this net protein synthesis ?


  • Energy Expenditure Increases Following An Isocaloric Ketogenic Diet In Overweight And Obese Men (from Hall, ICO2016)

    Contrary to the view that “a calorie is a calorie” whereby the ratio of dietary carbohydrate to fat has a negligible effect on energy expenditure if protein and energy intake are clamped, it has been hypothesized that habitual consumption of a high carbohydrate diet sequesters fat within adipose tissue resulting in adaptive suppression of energy expenditure. Isocaloric exchange of dietary carbohydrate for fat is therefore predicted to increase energy expenditure and fat oxidation resulting in body fat loss. To test these predictions, 17 overweight or obese men were admitted to metabolic wards and consumed a high carbohydrate diet for 4 weeks immediately followed by 4 weeks of an isocaloric ketogenic diet with clamped protein. The subjects lost weight and body fat throughout the study corresponding to an overall negative energy balance amounting to ~300 kcal/d. The ketogenic diet coincided with a rapid and persistent decrease in respiratory quotient (mean±SE; -0.111±0.003, p<0.0001) along with increased total energy expenditure (+57±13 kcal/d, p=0.0004) and sleeping energy expenditure (+89±14 kcal/d, p<0.0001) measured by metabolic chambers. Energy expenditure measured by doubly labeled water increased by 151±63 kcal/d (p=0.03). Body fat loss slowed during the first 2 weeks of the ketogenic diet and coincided with increased protein utilization and loss of fat-free mass. Therefore, an isocaloric ketogenic diet was associated with increased energy expenditure of ~100 kcal/d.