leucine topic lifted from avant

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leucine topic lifted from avant

Postby julesm on Wed Dec 23, 2009 12:01 am

should spark a bit of debate >>>>>>>>>>

http://www.mindandmuscle.net/forum/inde ... opic=40806

top and bottom of it- purports leucine as a stand alone may inhibit fat loss- so somewhat of an antithesis to current vogue
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Re: leucine topic lifted from avant

Postby Dtlv74 on Wed Dec 23, 2009 1:32 am

It's effects are on brown adipose tissue though - relevant to mice and hibernating mammals but not really adult humans as we lose almost all of our brown fat at around six months of age. If it were white adipose tissue would be more relevant.
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Re: leucine topic lifted from avant

Postby RoB on Wed Dec 23, 2009 2:38 am

Dtlv74 wrote:It's effects are on brown adipose tissue though - relevant to mice and hibernating mammals but not really adult humans as we lose almost all of our brown fat at around six months of age. If it were white adipose tissue would be more relevant.


Or if you live inside the arctic circle....
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Re: leucine topic lifted from avant

Postby Craig on Wed Dec 23, 2009 5:38 am

Dtlv74 wrote:It's effects are on brown adipose tissue though - relevant to mice and hibernating mammals but not really adult humans as we lose almost all of our brown fat at around six months of age. If it were white adipose tissue would be more relevant.



not true.


ABSTRACT

Background Obesity results from an imbalance between energy intake and expenditure. In rodents and newborn humans, brown adipose tissue helps regulate energy expenditure by thermogenesis mediated by the expression of uncoupling protein 1 (UCP1), but brown adipose tissue has been considered to have no physiologic relevance in adult humans.

Methods We analyzed 3640 consecutive 18F-fluorodeoxyglucose (18F-FDG) positron-emission tomographic and computed tomographic (PET–CT) scans performed for various diagnostic reasons in 1972 patients for the presence of substantial depots of putative brown adipose tissue. Such depots were defined as collections of tissue that were more than 4 mm in diameter, had the density of adipose tissue according to CT, and had maximal standardized uptake values of 18F-FDG of at least 2.0 g per milliliter, indicating high metabolic activity. Clinical indexes were recorded and compared with those of date-matched controls. Immunostaining for UCP1 was performed on biopsy specimens from the neck and supraclavicular regions in patients undergoing surgery.

Results Substantial depots of brown adipose tissue were identified by PET–CT in a region extending from the anterior neck to the thorax. Tissue from this region had UCP1-immunopositive, multilocular adipocytes indicating brown adipose tissue. Positive scans were seen in 76 of 1013 women (7.5%) and 30 of 959 men (3.1%), corresponding to a female:male ratio greater than 2:1 (P<0.001). Women also had a greater mass of brown adipose tissue and higher 18F-FDG uptake activity. The probability of the detection of brown adipose tissue was inversely correlated with years of age (P<0.001), outdoor temperature at the time of the scan (P=0.02), beta-blocker use (P<0.001), and among older patients, body-mass index (P=0.007).

Conclusions Defined regions of functionally active brown adipose tissue are present in adult humans, are more frequent in women than in men, and may be quantified noninvasively with the use of 18F-FDG PET–CT. Most important, the amount of brown adipose tissue is inversely correlated with body-mass index, especially in older people, suggesting a potential role of brown adipose tissue in adult human metabolism.
/quote]
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Re: leucine topic lifted from avant

Postby Dtlv74 on Wed Dec 23, 2009 4:06 pm

Craig wrote:
Dtlv74 wrote:It's effects are on brown adipose tissue though - relevant to mice and hibernating mammals but not really adult humans as we lose almost all of our brown fat at around six months of age. If it were white adipose tissue would be more relevant.



not true.


ABSTRACT

Background Obesity results from an imbalance between energy intake and expenditure. In rodents and newborn humans, brown adipose tissue helps regulate energy expenditure by thermogenesis mediated by the expression of uncoupling protein 1 (UCP1), but brown adipose tissue has been considered to have no physiologic relevance in adult humans.

Methods We analyzed 3640 consecutive 18F-fluorodeoxyglucose (18F-FDG) positron-emission tomographic and computed tomographic (PET–CT) scans performed for various diagnostic reasons in 1972 patients for the presence of substantial depots of putative brown adipose tissue. Such depots were defined as collections of tissue that were more than 4 mm in diameter, had the density of adipose tissue according to CT, and had maximal standardized uptake values of 18F-FDG of at least 2.0 g per milliliter, indicating high metabolic activity. Clinical indexes were recorded and compared with those of date-matched controls. Immunostaining for UCP1 was performed on biopsy specimens from the neck and supraclavicular regions in patients undergoing surgery.

Results Substantial depots of brown adipose tissue were identified by PET–CT in a region extending from the anterior neck to the thorax. Tissue from this region had UCP1-immunopositive, multilocular adipocytes indicating brown adipose tissue. Positive scans were seen in 76 of 1013 women (7.5%) and 30 of 959 men (3.1%), corresponding to a female:male ratio greater than 2:1 (P<0.001). Women also had a greater mass of brown adipose tissue and higher 18F-FDG uptake activity. The probability of the detection of brown adipose tissue was inversely correlated with years of age (P<0.001), outdoor temperature at the time of the scan (P=0.02), beta-blocker use (P<0.001), and among older patients, body-mass index (P=0.007).

Conclusions Defined regions of functionally active brown adipose tissue are present in adult humans, are more frequent in women than in men, and may be quantified noninvasively with the use of 18F-FDG PET–CT. Most important, the amount of brown adipose tissue is inversely correlated with body-mass index, especially in older people, suggesting a potential role of brown adipose tissue in adult human metabolism.
/quote]


i didn't know they'd found metabolically active BAT in adults so thanks for this, is interesting. However, am still not sure it's of much relevance to most people trying to lose fat (and would you really want to sacrifice the anabolic beneftis of leucine when training even if it was?) -

It says that 76 out of 1013 women and 30 out of 959 men had metabolically active BAT deposits in the neck to thorax region of more than 4 mm in diameter. This shows that while some people may have it, it's a low number and a small amount.

Also this is interesting "Most important, the amount of brown adipose tissue is inversely correlated with body-mass index, especially in older people".

This suggests it might be something relevant to skinny folk, possibly for maintaining warmth by thermogenic shivering (since that's what BAT is used for in babies and other mammals), but not the obese. So should those people be looking to lose this fat if it's metabolically important? And this doesn't make the leucine deprevation mentioned in the link particularly relevant to thermogenesis for fat loss in overweight humans with a high Body mass index (which would be due to WAT not BAT), as it suggests that BAT in humans is only present in active (but small) amounts in people with a low body mass index.
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Re: leucine topic lifted from avant

Postby Craig on Wed Dec 23, 2009 5:12 pm

Its the only study another smaller one had people wait in a cool room for 2 hours, it was a small study of 30 or so people all but one where fodund to have active BAT.

No I would not dump leucine for this reason but the how the whole BAT thing works in humans is as far as I can new territory.
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Re: leucine topic lifted from avant

Postby Dtlv74 on Wed Dec 23, 2009 7:20 pm

It's interesting for sure. Was just thinking about it whilst on my run (on icy roads, lovely) - maybe the location of the BAT in the neck and throax is to do with maintaining body temperature for the important organs located there. Is just a theory of course but makes sense in a kind of way. I think :? .
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