Tuesday, July 1, 2008

Intermittent Fasting - for longevity

Is this how intermittent fasting increases life span?

Researchers at UT Southwestern Medical Center have determined that starvation blocks the effects of growth hormone via a mechanism that may have implications in treating diabetes and extending life span.

“It’s been well-established that growth is blunted during starvation. But our work shows that this is not just from running out of energy. It’s much more sophisticated than that,” said Dr. Steven Kliewer, professor of molecular biology and senior author of a study available online and appearing in today’s issue of the journal Cell Metabolism.

Using genetically altered mice, the researchers found that during fasting, the actions of growth hormone are blocked by a fat-burning hormone called FGF21.

“It’s something that we hadn’t anticipated,” said Dr. Kliewer.

Growth hormone has many functions in the growth and reproduction of cells, such as controlling the length of developing arm and leg bones in children.

Growth hormone has several other functions, however, even in adults. It promotes the breakdown of fats, stimulates creation of protein and increases levels of IGF-1 (insulin-like growth factor-1), a hormone that promotes growth. Too much growth hormone can cause insulin resistance, resulting in diabetes, and lead to other disorders.

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IF Life


Mike OD - IF Life said...

Interesting...but do we really associate "Starvation" with IF? After all with IF there is no real calorie restriction or starvation response...so I doubt the mechanisms are the same. It may fit more along the lines toward long term CR therapy...but I think we have already seen that IF can provide the same results of CR without the negative side effects of starvation, loss of body composition (muscle) and well...starving. Still interesting thought on GH...as we need a healthy amount...but yes too much is never good as you can grow too much (gigantism) and also GH in a sick body only helps cancerous cells grow...which is not good. (why no one who has had or at risk for cancer before is allowed GH therapy)

Anonymous said...

The linked to study specifies that the fast was 24hrs for mice -- on the surface that seems like an IF fast, but perhaps the mice to man translation makes it different?

If not, the curious thing about this is that it seems to go against the grain of other IF studies reported on this website that suggest that an IF fast *promotes* GH release. Hmmmm. What gives?

donny said...

I was just buzzing around looking for klotho and growth hormone, to see if that path for longevity was similar and saw this study;


quote; "The klotho gene encodes a single-pass transmembrane protein that binds to multiple fibroblast growth factor (FGF) receptors and functions as a co-receptor for FGF23, a bone-derived hormone that suppresses phosphate reabsorption and vitamin D biosynthesis in the kidney."

It's a different numbered FGF, but hey.

donny said...

Anonymous--I'll be a busybody and answer you about growth hormone. Growth hormone release wasn't blunted, it's effect was. The study calls it growth hormone resistance.

Chris said...

Thanks donny

Chris said...


interesting piece here about IGF and GH and cancer.