carbs blunt growth hormone release

[Gabe Rinaldi]

I've read that the ingestion of carbs and subsequent increase in blood sugar blunts the increase of growth hormone one would expect from an appropriate GH inducing workout. Therefore, would it make sense to never eat carbs pre-workout to get the greatest GH increase? I'm speaking about a workout that lasts for 1 hour or less.

[Thom Downing]

OK, so I will bite. What about restoration of glycogen stores to the liver, as well as the muscles? I was under the impression that a 3:1 or 4:1 ratio of carbs to protein was ideal?

[Gabe Rinaldi]

I have also heard and recommended the 3:1 or 4:1 carb to protein ratio in the past. On one hand we're talking about hormones, and on the other we are talking about stored energy. It is true that during high intensity exercise glycogen is used as the primary energy source. However, the glycogen can be replentished by following a higher fat, adequate protein, and cyclical carbohydrate diet (not consuming carbs pre or post workout). This would theoretically get you optimum hormone levels as well as stored fuel. How say you?

[davidama]

The people that I know usually follow that rule only when doing AM cardio. When talking about weight training, even when dieting, people will consume carbs pre-workout and post. The rest of the day, insulin will be kept low by eating low carbs, thus taking advantage of the GH throughout the day.

[Scott Kolasinski]

Gabe, are you referring to a resistance training workout?

[Gabe Rinaldi]

Scott - yup, a resistance training workout.

Here's where I read about this:

http://www.extique.com/NHE-Chapter-21.pdf

I also really like this guys explanation of his different definitions of intensity. I am using some of this information for a newsletter article I am writing.

Let me know your thoughts specifically about this issue - carbs blunting GH.

[Scott Kolasinski]

Unfortunately, this is not as black and white of an issue as what this author, or other authors like him, such as the cyclical-ketogenic diet inventor, Dr. Mauro Di Pasquale, would like us to believe. Check out some of the abstracts below.

On the other side, the writings and research of Dr. Louise Burke and Dr. John Ivy will get anybody to believe that the timing of carbohydrate ingestion pre-exercise and post-exercise is the best way to stimulate muscle bulk because of its effects on insulin. Once you're done reading their stuff, you're always going to want to have some insulin.

This whole carb-bashing-type of literature I always enjoy. It goes against the norm and gets debates going like political conversations. However, it does not go without saying that there is not any literature out there that shows that carbs and amino acids pre-exercise are not beneficial on growth hormone, and more importantly, strength, hypertrophy and performance. I like to know both sides of the issue. I won't bore anybody with more references unless questioned.

The one thing that I didn't find as I skimmed through this article was that glucose or carbohydrate-rich meals that increase blood glucose generally decrease GH levels initially and may be followed by a rebound hypoglycemia-induced rise in GH. Is it enough to create an effect on performance or physiology? Dunno.

Some older studies have shown that increased circulating fatty acids have also shown to inhibit GH secretion.

So we've run through all the macronutrients that have been shown to affect GH. I have no problem with people trying various macronutrient profiles of dieting. if it works for you go for it. The fact is there are numerous successful athletes. Unfortunately, they all don't eat the same. They have different physiology, but a lot of them may have similar-like pharmacology, but that's a different issue.

Sports Med. 2006;36(3):215-38.

Possible stimuli for strength and power adaptation : acute hormonal responses.

Crewther B, Keogh J, Cronin J, Cook C.

The endocrine system plays an important role in strength and power development by mediating the remodelling of muscle protein. Resistance training scheme design regulates muscle protein turnover by modifying the anabolic (testosterone, growth hormone) and catabolic (cortisol) responses to a workout. Although resistance exercise increases the concentrations of insulin-like growth factor 1 in blood following exercise, the effect of scheme design is less clear, most likely due to the different release mechanisms of this growth factor (liver vs muscle). Insulin is non-responsive to the exercise stimulus, but in the presence of appropriate nutritional intake, elevated blood insulin levels combined with resistance exercise promotes protein anabolism. Factors such as sex, age, training status and nutrition also impact upon the acute hormonal environment and, hence, the adaptive response to resistance training. However, gaps within research, as well as inconsistent findings, limit our understanding of the endocrine contribution to adaptation. Research interpretation is also difficult due to problems with experimental design (e.g. sampling errors) and various other issues (e.g. hormone rhythms, biological fluid examined). In addition to the hormonal responses to resistance exercise, the contribution of other acute training factors, particularly those relating to the mechanical stimulus (e.g. forces, work, time under tension) must also be appreciated. Enhancing our understanding in these areas would also improve the prescription of resistance training for stimulating strength and power adaptation.

Med Sci Sports Exerc. 2005 Mar;37(3):395-403.
High-affinity growth hormone binding protein and acute heavy resistance exercise.

Rubin MR, Kraemer WJ, Maresh CM, Volek JS, Ratamess NA, Vanheest JL, Silvestre R, French DN, Sharman MJ, Judelson DA, Gomez AL, Vescovi JD, Hymer WC.

PURPOSE: The purpose of this investigation was to examine the influence of resistance training on circulating concentrations of growth hormone binding protein (GHBP) in response to acute heavy resistance exercise. METHODS: Using a cross-sectional experimental design, a group of resistance-trained men (RT, N=9, 7.9+/-1.3 yr resistance training experience) and a group of untrained men (UT, N=10) performed an acute heavy resistance exercise protocol (AHREP) consisting of 6 sets of 10 repetition maximum parallel squats. Blood samples were obtained 72 h before exercise, immediately before exercise, and 0, 15, 30, 45, and 60 min after exercise. RESULTS: Significant increases (P<0.05) in GHBP, immunoreactive growth hormone (iGH), and IGF-1 were observed in both subject groups after AHREP. There were no differences (P>0.05) between groups in GHBP at rest or after AHREP. However, RT exhibited a significantly greater iGH response to AHREP than UT subjects, and significantly higher IGF-1 values at rest and after exercise. Significant positive correlations were found between GHBP and BMI, body fat, and leptin in both groups. A significant positive correlation also was observed between resting leptin and GHBP values in UT but not RT subjects. CONCLUSIONS: In summary, these data indicate that resistance training does not increase blood GHBP. Nevertheless, the increases observed with IGF-1 concentrations in the resistance-trained subjects do suggest an apparent adaptation with the regulation of this hormone. If there was in fact an increase in GH sensitivity and GH receptor expression at the liver that was not detected by blood GHBP in this study, it may be possible that factors contributing to the circulating concentration of GHBP other than hepatocytes (e.g., leptin and adipocytes) may serve to mask training-induced increases in circulating GHBP of a hepatic origin, thus masking any detectable increase in GH receptor expression.

[John Seaburg]

I've been told if you eat anything sweet like sugar or starchy carbs, especially in the evening, you won't get as good a GH spike while you sleep.