This is not meant to be a comprehensive guide to growth hormone function in the face of diet and exercise. Rather, I’m going to suss out some of the misconceptions that clients are laboring under, based on some questions I’ve recently had.
Growth hormone (GH) is a hormone which has an effect on both tissue growth and fuel mobilization. GH is released in response stressors like exercise, reductions in blood glucose, and both carb restriction or fasting. Shock of shocks, GH is a growth promoting hormone, increasing protein synthesis in the muscle and liver. GH can only carry out these actions through Insulin-Like Growth Factor 1 (IGF-1), which it stimulates the liver to release in the presence of insulin. To put it another way: high GH without high insulin equals little to no IGF-1.
So what about GH as it pertains to training and recovery? Well, before I get into research on how GH is released throughout the day and in response to training, I want you to know that at the end of this article I attached a list of studies that show the result of injecting GH on muscle mass and performance. Give it a look after this article.
So training does result in a GH increase. In fact it’s big in untrained subjects (10 fold increase above baseline), it’s not quite as big in trained guys (4-5 fold increase) (1,2). The thing is that it’s super brief, like back to baseline levels in an hour brief (3). Sounds great though, right? Five times higher than baseline? Here’s the thing: GH released during sleep is up to 20 times above baseline and lasts a lot longer, up to 3 hours (4). Finally, I’ll just quote this meta analysis on the subject of GH and athletics:
Claims that growth hormone enhances physical performance are not supported by the scientific literature.
What about GH’s role in fat loss? Doesn’t GH need to be elevated to move fatty acids for energy use? Well, take a look at this study of individuals with hyperinsulimia in which they lost 20lbs in 60 days. The drastically elevated insulin *should* have blunted the GH, which *should* have trapped the FFA’s for all eternity…but it didn’t seem to matter because they were eating less. This is why all of those “GH Diet” scams are successful: if your calories are low enough AND you’re injecting GH you’ll lose a bunch of fat. But it’s the low calories that let this happen, not the GH per se.
But I hear you all the way through the internet: I want to make sure I get whatever tiny cookie of benefit GH has to offer…should I avoid carbs after a workout to keep GH high?
Did a caveman tell you this? I really with this paleo myth would die, be buried, and be discovered by Jack Horner’s great^20 grandchild as an anthropological study of how little we knew.
Here’s the thing: GH is made higher post workout with the inclusion of carbs. So am I suggesting a big huge spike in insulin, meaning a metric ton of carbs post workout? Nay, but since you no longer have to worry about blunting GH, why not ensure protein synthesis occurs? A very small increase in insulin is needed to start protein synthesis, which is to say that a whey shake would get the job done very adequately.
Books have been written on this subject, but there’s not been Earth-shattering changes to this suggestion: if muscle gain and recovery are really really important to you, just eat a nice meal sometime soon after you train. You don’t have to rush it either; the post-workout window of opportunity is large enough to drive a truck through…just don’t decide to fast for 16 hours after the workout and you’ll cover your bases
Skyler Tanner is an Efficient Exercise Master Trainer and holds his MS in Exercise Science. He enjoys teaching others about the power of proper exercise and how it positively affects functional mobility and the biomarkers of aging.