“I have always trained the same, higher volume, short rest periods; it keeps it challenging which I thrive on.” - Jay Cutler

In Part I of this article, we looked at the impact training intensity has on GH, as well as when one should supplement with BCAAs to maximize their impact. Now let’s turn our attention to how GH affects adipose tissue, fat loss and obesity.

GH Preferentially Burns Abdominal Adipose Tissue

Interestingly GH stimulates adipose tissue mobilization after a delay of approximately 2 hours (3). During sleep, the peaks in GH result in maximal levels of free fatty acids about 120 minutes later (9). Additionally, GH increases circulating levels of glycerol and free fatty acids in GH deficient men after a lag time of 2-3 hours (12).

So if you are trying to get ripped, is one little peak in GH during your workout going to make that big of a difference in your physique? Your damn right it does! Researchers took subjects and gave them a dose of GH but kept it in the physiological range; a single GH spike increased fat mobilization in femoral (thigh) and abdominal adipose tissue, the greatest increases being more prominent in the abdomen. The more pronounced effect of fat mobilization in abdominal adipose tissue may be the reason why GH deficient men look like they are pregnant and hold most of their fat in their stomach. The lipolytic response is two to threefold more pronounced in the abdomen; the effects of GH will lead to preferential loss of abdominal subcutaneous fat10. When obese men are administered GH the fat seems to just melt off.

For example, thirty men, with abdominal/visceral obesity were treated with recombinant human GH in a 9-month randomized, double-blind, placebo-controlled trial. The mean total bodyfat dropped by 9%, moreover, the volume of visceral adipose tissue (stomach) decreased by 17%, whereas no changes were seen in the placebo group.

No Increase in Post Exercise Fat Utilization without Acute Exercise Increases in GH

Since there is a delay in GH’s effect on fat metabolism, back in 2005 researchers wanted to see exactly what acute increases in GH did to fat metabolism after exercise. They gathered test subjects and had them cycle @ 70% of their peak exercise capacity. Post exercise fat metabolism was directly related to the acute rises in GH that occurred during the exercise protocol (6). Based on the study, the best way to increase your fat metabolism post exercise is to increase your GH levels.

It is well established that prolonged rest periods (3-5 minutes) result in very small rises in GH compared to taking short rest periods which leads to large increases in GH. Is there any metabolic advantage of the large increases in GH that occur with short rest periods for increasing fat metabolism?

According to a new study, the acute increases in GH are essential for increasing post exercise fat utilization. Here was the study design. Researchers had subjects exercise for 1 hour. One group served as a control group while one group of subjects received an infusion of Octreotide (a potent inhibitor of growth hormone) which as an injectable formulation for the treatment of acromegaly (GH excess). The control group had a fourfold rise in GH while the group receiving Octreotide had a blunted GH response during exercise. Researchers found that post exercise fat utilization in subcutaneous adipose tissue was increased due to GH while it remained unchanged in the group receiving the drug that blunted GH responses during exercise (4).

Researchers suspect the reason GH peaks about 2 hours after an intense bout of exercise is that glycogen needs to be replenished during that time. As a result, high levels of GH increase fat mobilization to spare glucose which is being incorporated into glycogen. So if you are looking to get lean, in addition to diet, large increases in GH from high intensity exercise may facilitate this process.