GH-gut, Roid-gut – or just muscle-gut?

I recently came across this sweet study, in which a Japanese group of researchers looked into changes in organ sizes with changes in body weight in collegiate football players (yes, they do play football in Japan). Their data really struck something with me, because I’ve been pondering for some time what the huge distended guts seen in bodybuilding actually consists of. Is it occult visceral fat storage, swollen livers, ascites fluid, connective tissue, thicker musculature of the pelvis or Chest-bursters waiting to wreak havoc on the world? Hard to tell really


The infamous GH/roid-gut is the distended belly sometimes seen in bodybuilders. This is especially characteristic when they are in competition shape because everything on their bodies is ripped and fat-free, but there it is – the huge gut hanging out, at least when they are not paying attention to forcing it in.

kai greenes distended gut

Kai Greene’s wonderful pregnant belly

In the contemporary debate, this is normally termed GH-gut or Roid-gut, obviously associating these guts with particular drugs (GH for recombinant human Growth Hormone). In the blogosphere and discussion boards, it is also frequently associated with the use of insulin and less frequently other peptide hormones.

While there is no doubt that the use of various purportedly anabolic peptides is on the rise and has been so for the last 15 years, the use of anabolic steroids probably hasn’t changed drastically. The way in which insulin should do this, is through visceral or organ fat storage, which could in principle be true, but given the harsh diets and fat burning drugs frequently used during bodybuilding contest preparation, I have a hard time believing that large amounts of fat could be trapped in the liver and around the intestines while the skin is paper-thin. Not happening if you ask me.

The mechanism behind GH-induced gut hypertrophy should be that GH makes the organs grow, which has indeed been shown to happen (Flyvbjerg et al, 1991). But unbeknownst to most of the anabolic drug aficionados claiming GH to the main reason behind the distended bodybuilder guts, testosterone has been shown to do exactly the same (Kochakian et al, 1948). While both of these citations are from animal studies, the function of these hormones remains very conserved among mammals and it is highly likely that they’re causing the same effects in humans.

So even though the drug regimens in use by bodybuilders have been intensified and the bodybuilders have gotten a LOT bigger, it’s not like the pharmacological impact on the gut has changed qualitatively over the last 10-15 years. And this is a beautiful segway to the next paragraph ;o)

The Japanese study

The Japanese study mentioned above consists of two parts (Miyauchi et al, 2013). The first is an observational study looking at the freshman and senior football players and the second part is an intervention study. In the first part, the researchers first look at differences in the body composition between freshman and senior football players. They report that as a consequence of intense bulking protocols and resistance training regimens, the football players on average weighed 17 kgs more as seniors than as freshmen. This can be broken down into 11-12 kgs of lean mass and 5-6 kgs of fat mass (“serious bulking, bra!”). They also report that the weights of the heart, liver, and kidneys increase significantly. And interestingly enough these increases are pretty much proportional to the increases in muscle and fat mass.

Table 1 from Miyauchi et al al, 2014

Table 1 from Miyauchi et al, 2014

In the second part of the study, they try to reproduce this change in an intervention study by taking freshman players and putting them through a controlled bulking and training protocol over a year, to reproduce these changes. And lo and behold, they get pretty much the same results as in the observational study. The changes were slightly smaller than the differences reported in the observational study, but this is likely caused by the fact that the intervention study was with only one year of training, whereas the observational study was based upon seniors that had been bulking and training for 2-3 years thus having had more time to grow.

Data from part II of the study

Data from part II of the study

Naturally, one cannot exclude the possibility that there have been drugs involved in the hypertrophy in the study and that the results were therefore actually caused by anabolic drugs, but I’ll go out on a limb and hope that the researchers would have excluded obvious “users”. Also, the gain of lean body mass relative to the gain in fat mass were certainly not impressive enough to raise any red flags regarding suspicions of drug use.

What to make of this

Well, if you’ve read this far, you probably already know where this is heading. I don’t think that the huge guts seen in bodybuilders are caused directly by drugs. Hell, I’m not even sure that the increases in organ weight in the animal studies with testosterone and GH are caused directly by the drugs (yes, both testosterone and GH can increase organ weight in both human and animal studies). I think that the number one reason for organ growth is whole-body growth, which is naturally secondary to the intense use of anabolic hormones (and apparently bulking and training). As the bodies in competitive bodybuilding have grown bigger, so have the organs. Arnold was 185 cm and 110 kgs in competition shape, whereas modern top 5 Mr. O contenders are 5-10 cm shorter AND 15-25 kgs heavier. AND leaner. AND drier. And these massive bodies require massive organs. The studies I have cited here have only looked into kidney, liver and heart weights, but I’m pretty sure that the weight of the intestines and other smaller organs follow the same pattern. And the amount of space available in the abdomen doesn’t really change. If anything, it decreases as the trunk and pelvic musculature becomes thicker, leaving even less space to the growing organs and intestines. While this may not explain all of the guts sported in modern bodybuilding, I’m pretty sure it accounts for most of it. But I think it’ll be hard to get grant money for a study into this in gear-using bodybuilders ;o)


Flyvbjerg, A., Jorgensen, K. D., Marshall, S. M., & Orskov, H. (1991). Inhibitory effect of octreotide on growth hormone-induced IGF-I generation and organ growth in hypophysectomized rats. American Journal of Physiology Endocrinology and Metabolism, 260(4), E568–E574.

KOCHAKIAN, C. D., & STETTNER, C. E. (1948). Effect of testosterone propionate and growth hormone of the weights and composition of the body and organs of the mouse. The American Journal of Physiology, 155(2), 255–261.

Miyauchi, S., Oshima, S., Asaka, M., Kawano, H., Torii, S., & Higuchi, M. (2013). Organ size increases with weight gain in power-trained athletes. International Journal of Sport Nutrition and Exercise Metabolism, 23(6), 617–623.


  1. Hemming on 2014-06-26 at 13:27

    Interesting post, I've also always thought that it was simply 'roid-gut'.

    I lost a lot of weight coming from a normal weight down to a very unhealthy one and I also got this pot belly. This was probably mainly due to osmosis but I'm also thinking if people who lose weight down to that level will have organs which are 'too big' for their bodies so that they have a protruding belly?
    Now that I've gained some weight back I look a lot better but still have a little lump on the lower part of the stomach which really annoys me 🙂

    • incognitodk on 2014-06-26 at 13:36

      Well, if my idea about the nature of the gut is real, then the organ size should normalize with time. However, the real reason for your could still be visceral or subdermal fat if you're otherwise healthy


      • Hemming on 2014-06-26 at 13:46

        Yeah, I also think that the body has a preference for putting fat on the belly in the situation of coming from starvation to normal eating. I can still fell I've lost a lot on my buttocks and thighs. I guess this is one of the side effects of elevated cortisol during a long period. Some explanation for my protruding belly was also edema.

        Btw, do you work as a personal trainer too?

        • incognitodk on 2014-06-26 at 13:49

          I also believe that people that have had a big abdominal overweight are more prone to so-called gluteal amnesia. And yes, i do PT as well. But only in my spare time ;o)


          • Hemming on 2014-06-26 at 14:00

            That's interesting – I sure hope that I can gain the muscle back which I've lost during my anorexia.

            Do you mean you only train friends or is it possible to have you set up a training and/or diet program?

          • incognitodk on 2014-06-26 at 14:09

            I do paid PT and distance programming. The timing is not very good right now as I'm going on my summer holiday tomorrow. Is your email the one you used for the comment? If so, I can write you after my 2 weeks of holiday ;o)


          • Hemming on 2014-06-26 at 14:23

            Sure, lets speak when you're back.

          • incognitodk on 2014-06-26 at 14:30

            You're in my calendar now ;o)

  2. Muscle athletes on 2014-06-26 at 15:42

    very useful article thank you

    • incognitodk on 2014-06-26 at 15:43

      You are very welcome, thank you


  3. cbonzirven on 2014-06-26 at 18:33

    Even if the large guts aren’t directly caused by GH, they are de facto caused by it. You didn’t see these types of large guts in bodybuilders of the 70s and 80s, despite the training and drug use that went on during that time period. GH makes the huge guts possible.

    • incognitodk on 2014-06-26 at 19:20

      Hi Cbonzirven
      As much as i appreciate your argument, and agree that the drugs are permissive to the massive bodybuilders seen today, there is really no proof or supporting evidence of this point of view. The appearnce of peptide hormones is not the only thing that have changed. People are using much bigger dosages of AAS too. And the japanese study shows pretty well that the organs seem to follow the body size, irrespective of hormones. And with a 120+ kgs of LBM, there isn't room for these organs anywhere else. I totally agree that the huge bodies are only possible courtesy of drugs, but that doesn't mean that GH or AAS directly cause the gut.


    • twistedchild on 2016-02-19 at 02:07

      Yeah… completely agree.

  4. Becky on 2014-10-09 at 22:32

    A well-written, indepth article. Thank you for posting!

    • incognitodk on 2014-10-10 at 08:47

      Thank you becky ;o)


  5. Jon on 2014-12-03 at 02:50

    The reason the people in the study grew was because they were in puberty. And during that time you produce more hgh and testosterone, and because they are naturally growing, the organs will grow as well. In a fully grown adult the organs won't grow unless you take hgh and testosterone (both have been show to cause it). You also state you don't think the large guts are caused by the drugs but rather by whole body growth. Well yes they are caused by whole body growth but the whole body growth is caused by the drugs. The drugs are directly responsible.

    • incognitodk on 2014-12-03 at 09:25

      The increases in organ size were in this study were in the order of 6.5 to 18 percent. That is A LOT more than the normophysiological changes that occur during one year in 18-year olds. A LOT more. Ask any anatomy teacher experienced in adolescent anatomy. The changes that should occur during this period (in absence of bulking) would be on the order of 2-4 percent, tops. This makes your suggestion highly improbable. Reading your post, I get a sense of someone desperately clinging to a darling argument of his ;o) I'm not saying that hormones are not contributing to distended guts seen in bodybuilding, just that the majority of the associated organ weight can be accounted for by normal physiological factors.


  6. Alex on 2014-12-03 at 18:24

    why do bodybuilders today have the big guts, but bodybuilders years ago did not? Not sure if you addressed this in the article but just wanted clarification. Thanks

    • incognitodk on 2014-12-04 at 10:39

      Well, my main argument is that for the most part, the organs follow the body size and therefore that the major effect of hormones on organ size is indirect, i.e. through making the body bigger, rather than direct, as the terms GH-gut or roid-gut are alluding to. I'm not saying that hormones are NOT contributing directly to organ growth, just that the major part of the gut hypertrophy can be explained by sheer body size. This leads to my answer to your question, which is that the average IFBB pro has been getting more massive since bodybuilding started. Hope this is making sense.


  7. lisaedward2691 on 2014-12-15 at 08:04

    Informative post…Great explanation about training after and before overfeeding… Amazed by the information

    • incognitodk on 2014-12-15 at 10:32

      Thank you. Although i kind of suspect the main purpose of the post was link doping ;o)


  8. Vi Offutt on 2014-12-22 at 14:49

    It's really great for me to visit your blog and seeing a bunch of great articles about various topics. Thanks for all these sharing.

    • incognitodk on 2014-12-23 at 11:25

      Thank you very much!


  9. Phil Slater on 2017-01-27 at 09:21

    Great post, Dr. Muskel! I’ve seen several bodybuilders with gh gut and it looks really horrible it’s ruining the overall appearance of their body. The lesson here is not to overdo it and never abuse supplements. Thank you for sharing this very informative post.

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