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.
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.
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.
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.