Quote:
Originally Posted by Subby
The relationship between fasting and growth hormone secretion seems almost too good to be true. Is this a generally accepted fact or is it something that has been observed but needs more study?
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https://www.dietdoctor.com/fasting-and-growth-hormone
The "Fasting to increase growth hormone" section references a few actual studies.
Quote:
In 1982, Kerndt et al published a study of a single patient who decided to undergo a 40-day fast for religious purposes.
But our concern here is HGH. It starts at 0.73 and peaks at 9.86. That is a 1,250% increase in growth hormone. A shorter 5 day fast gives a 300% increase. All this HGH increases without drugs.
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This is another study referenced in that dietdoctor entry:
Fasting enhances growth hormone secretion and amplifies the complex rhythms of growth hormone secretion in man.
Quote:
The 24-h IGHC (micrograms per minute per milliliter) increased
after 1 d of fasting (2.82±0.50 vs. 7.82±1.12, control
vs. day 1; P = 0.0009) and remained elevated on day 5
(8.75±0.82). The pulsatile component (Fig. 2) of GH release
followed a similar pattern with an increase on day 1
(2.07±0.47 vs. 5.74±0.78, control vs. day 1; P = 0.0013) but
no further increase on day 5 (4.25±0.67). In contrast, although
there was a strong trend in the nonpulsatile component of GH
release to increase on day 1, no significant change was noted
(0.75±0.11 vs. 2.08±0.53, control vs. day 1; P = 0.10). By day
5, however, nonpulsatile GH release was markedly enhanced
(4.50±0.75; P = 0.0002).
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I haven't tried to rabbit-hole past this yet I don't know what pulsatile vs non-pulsatile is, but these results seem to make it sound like growth hormone was very clearly increased in general. That's the conclusion made by the article linking to it as well. This only had 6 subjects, it should be noted.
https://www.ncbi.nlm.nih.gov/pubmed/1548337
Here's the last study referenced in that dietdoctor article that seems to show similar results over 2 days of fasting. The full article is not referenced in this one.
This increase in growth hormone is given as a reason (THE reason, perhaps?) that lean mass is not decimated during fasting.