Growth Hormone (GH) Release and Fat Loss – Q&A

On Tuesday of last week I ran a research review on Casein Hydrolysate and Anabolic Hormones and Growth looking at two papers, one of which was a paper showing that the acute hormonal response (in terms of testosterone and growth hormone) to weight training had zero impact on growth.  In the comments section, at least three different people asked a semi-related question that I’ve reproduced below and which I want to address in some detail today.

Question: A common recommendation bandied about by trainers is to place any LISS cardio after “lactate training” or whatever they choose to call higher intensity work, and they say that if fat loss is the aim, this will milk every last bit of effectiveness out of the low intensity work (versus keeping it a separate session entirely). And they usually say that increased lactate leads to increased GH, leads to increased lipolysis, so that when the low intensity work comes after the much higher intensity work, you oxidize more of the fat they claim gets mobilized.  So does this pairing of LISS cardio after high(er)-intensity work still make it at least somewhat more effective (from a fat-loss standpoint) than when performed separately? And if so, is it more due to other things you mentioned (glycogen depletion, effect of the catecholamines, etc.), so that the intended effect is the same, it was just the purported reason for the effect that most of these trainers had wrong (namely implicating a GH-induced increase in lipolysis as the reason)?

Answer: There’s no doubt that growth hormone (GH) is involved in lipolysis although, compared to hormones such as insulin and the catecholamines (epinephrine/norepinephrine aka adrenaline/noradrenaline) it plays a distinctly secondary role.  There are other hormones of course, testosterone, estrogen, progesterone, Interleukin-6 and a new player called atrial-natriurietic peptide (ANP) all play a role as well.  Here I’m only going to talk about GH.

First let me define a single term which is lipolysis.  This refers to the breakdown of stored fat (technically: triglycerides) in fat cells for release into the bloodstream.  While there are more steps involved in losing fat (and the specific pathways are all discussed in some detail in The Stubborn Fat Solution), clearly if you can’t get the fat out of the cell in the first place, little else matters.  Lipolysis simply refers to that process, whereby fatty acids stored within fat cells are broken down to be released into the bloodstream, hopefully to be burned elsewhere in the body (generally skeletal muscle or liver).

For example, while studies of injectable GH have generally crapped out in terms of muscle growth (there is an increase in lean body mass but it’s primarily water and connective tissue, not actual muscle mass), it has shown impact on fat loss.  As well, the nighttime GH pulse has been shown to be important for lipolysis the next day.  Finally, during periods of fasting or even low-carbohydrate diets, studies clearly show that blocking the normal GH response not only limits lipolysis, but this ends up increasing muscle loss (because the body doesn’t have fatty acids to burn).

So far so good right?

Add to that a host of studies done primarily during in the 80’s by William Kraemer and his group showing that certain training protocols (notably higher reps and short rest periods; 3X10 with 1′ rest was typically used) elevate GH and you can see where folks got the idea that training in this fashion would be good for fat loss.

I think the first place I saw this idea floated was Charles Poliquin’s original German Body Composition Training.  Claimed to be based on German research into the hormonal response to training, it was based arund multiple sets of high reps with short-rest, the premise of which being to raise GH (and lactate production during training seemed to be involved somehow) to increase fat loss.

More specifically to today’s question, many trainers will use that type of training (using various permutations of Metabolic Training, discussed in some detail in Weight Training for Fat Loss Part 1 and Weight Training for Fat Loss part 2) to be followed up by low-intensity cardio.    The idea being that the GH response will promote lipolysis and the low-intensity cardio will then ‘burn off the fatty acids’.

And here’s we run into the problem with the idea:   the time course.  Because while GH is certainly involved in lipolysis, it’s effects are pretty slow to occur.  Cutting ot the chase, after a big GH pulse, you don’t really see a big increase in lipolysis or blood fatty acids until about the 2 hour mark.  Which means that a protocol based around the idea of elevating GH during the intense portion so that cardio done a few minutes after will burn off the fatty acids mobilized by the GH pulse is fundamentally incorrect from a physiological point of view.

But that doesn’t mean it doesn’t work.  Quite in fact, the premise is still fairly sound, this is just a place where I’m being picky about the mechanism.  As discussed in Weight Training for Fat Loss Part 1 this type of training still has metabolic effects that can be conducive to fat loss (even acutely), they simply aren’t related to the GH pulse in any form or fashion.

Rather, increases in epinephrine/norepinhrine will have a much stronger acute effect on fat mobilization, and the glycogen depletion due to this type of training tends to enhance fat oxidation in skeletal muscle.    Quite in fact, the two advanced protocols in my Stubborn Fat Solution are at least superficially similar to this type of training, high-intensity work followed by low-intensity work.  But GH isn’t the mechanism behind it.

So bascially, what the person asking the question wrote in the second-half of his question.  The combination of high-intensity  followed by low-intensity work can still be effective for fat loss, it’s simply not for the mechanism stated.  The impact of GH on fat loss is simply too slow to be involved.  Rather, other mechanisms related to hormonal response, glycogen depletion, etc. are what are involved and responsible.  GH simply isn’t relevant to the process in that short of a term.



12 thoughts on “Growth Hormone (GH) Release and Fat Loss – Q&A

  1. So what, if any benefit, is there from taking injectable GH (and test). I’m a 59 year old male. I’ve been lifting for about 4 years now, never having done so before, and have made some significant progress. I have VERY low blood tested levels of GH (and test, for that matter), though, and my doc (who has watched my progress and is, I think, just trying to be helpful, is suggesting I consider therapeutic dosages designed to restore GH and Test levles to the putative “satd” levels for 20 year olds.

  2. Lyle. Thanks for this. I’m happy you clarified this.

    Does elevating GH still has some favorable effect on fat loss over long-term? Or as you said, this type of training works but it’s unrelated to GH? (I’m not sure if I understood well)

    And does lactate really makes GH peak? (could you point studies?)

    Many thanks!

  3. Frank: As noted, injectable GH certainly impacts fat loss but the simple fact is that small pikes in GH due to training are unlikely to affect much of anything. As well, I’m not sure if anyone ever showed mechanistically that lactate was involved in the GH pulse. It’s simply that the same types of training that tend to raise lactate (high rep/short rest) is associated with a bigger GH pulse (compared to other types of training). Kraemer did a bunch of that work in the 80’s and 90’s.

    Sperwer: Sort of tangential to the article. Injectable stuff does very different things than small training related spikes. Certainly testosterone replacement appears to have some benefit (in terms of helping with muscle loss issues that occur with aging, with ‘andropause’ being a new catchphrase). Of course, it’s also involved in some types of cancer (e.g. prostate) so there are always pros and cons.

    I think the use of GH is a bit more debatable. It certainly can reduce body fat, improves connective tissue health but it can also cause insulin resistance and other problems. For the price I’m not convinced it’s that worthwhile but this is also a bit outside of my area of interest.

  4. Lyle,

    Thanks a lot for taking the time to expand on your answer from the comments section. I think you said it yourself before: with fitness research/science, people take results and try to work their way backwards, instead of doing it the other way around like every other field of science. We’d be a lot better off if more were willing to admit “Hey, I know this works but I honestly don’t know why, it just does”. Or if we just had more people like you who did know how it works. Yea, that too.


  5. If GH raise after high-rep/short rest type of training is postponed, would there be any benefit of that kind of training in the morning that would start raising GH levels, and using that raise (increased lipolysis) doing aerobic training later in the day when GH (if it is?) is increased?
    You said that one can see the increase in lipolysis 2 hours after the above mentioned type of training, but it would be important knowing WHEN does the GH level PEAK happen?

  6. The night time GH pulse is important for lipolysis the next day. I know you usually say if you are still in a caloric deficit for the day, late night carbs don’t matter. But if insulin interferes with the night time GH release doesn’t that support not eating carbohydrates before bed?
    I am doing IF (for fat loss) and cant afford to inhibit next day fat burning

  7. Hey Lyle. I just received your books nutrition for mixed sports and ultimate diet 2.0. As always incredibly high quality. Every time I open them I learn something that I forgot from last time I read them! I just wanted to talk about quickly about the very brief glutamine/GH mention that you talked about in UD2.
    For the last 12 months I’ve been looking at supplementation to improve glucose metabolism. I get chronic tired spells throughout the day (can barely stay awake) – which sucks because your training well and eating pretty well and you still feel like shit!. So I’ve tried chromium, gingo biloba, B vitamin complex and a garlic ALA complex and then combined them in a few different ways. They all had very subtle effects. But nothing you would call significant. The result being that I’ve had to continue caffeine intake just to stay awake, which I’m not a big fan of (I keep it to an absolute max of 3 half teaspoon instant coffee’s per day but still literally need it).
    So yesterday I tried Glutamine before sleeping on a (fairly) empty stomach. The next morning before eating I had a tyrosine glutamine mix (I don’t know what the dosage was approx 1 teaspoon each). Holy Shit! I was flying for the rest of the day! The coffee call went out round the office that morning and the thought of having a coffee literally worried me (jitters!). I was revved all day and worked that night at a bar as well till 3am having 1 diet pepsi!
    You’ve got no idea how psyched I am that I’ve taken a step closer to taking controll of my energy levels. Particularly after having faith in a few other supplements which didn;t work out. I know you argue that GH takes a back seat to E/NE and also Insulin but perhaps GH has more of a priming role for N/NE and insulin. Potentially making it more important. But I’ll leave that to you. Thanks Lyle your a legend and your books are priceless. Looking forward to more great information from the master.

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