Leucine While Fasting

[Peter Borden]

Anyone use Leucine during the fasting period to try and offset and potential muscle loss during the fasting period, since it independently stimulates muscle protein synthesis, even without Isoleucine and Valine. There has been several studies, many in rodents unfortunately, and some in humans that show leucine seems to have an anti-catabolic effect to muscle during fasting.

Even though the other amino acids aren't there, leucine can still promote muscle protein synthesis, and seems to help prevent the elevation of blood amino acids leaching from muscle during a fast. It can also act as a gluconeogenic precursor, offsetting some of the muscles release of amino acids to provide glucose.

Leucine is pretty cheap and actually mixes decently with enough water. The taste is unpleasant but nothing too terrible.

My thoughts would be to mimic infusion and sip on a leucine drink every hour or so.

[Tony Ferous]

My unscientific reponse would be, if your going to fast, why not actually fast?

Many of us are, myself included, are guilty of micro managing our diets to our own detriment!!

[Mike ODonnell]

Fasting increases GH and other muscle sparing mechanisms....so loss of muscle should not be an issue...unless you are doing extended fasting over 36hours. Most supplements give you little return in general unless you are talking about GH or Test. As long as you are eating enough protein during your feeding hours, not overtraining and getting plenty of sleep....muscle loss should not be a problem. That whole nitrogen balance paranoia is sold by the supplement and BB industry that lives on selling protein powders and other supplements. The body is perfectly capable of breaking down it's own muscle tissue and reusing amino acids again....otherwise we would have died off long ago as a species.

[Stuart Mather]

Originally Posted by Peter Borden

Anyone use Leucine during the fasting period to try and offset and potential muscle loss during the fasting period, since it independently stimulates muscle protein synthesis, even without Isoleucine and Valine. There has been several studies, many in rodents unfortunately, and some in humans that show leucine seems to have an anti-catabolic effect to muscle during fasting.

Even though the other amino acids aren't there, leucine can still promote muscle protein synthesis, and seems to help prevent the elevation of blood amino acids leaching from muscle during a fast. It can also act as a gluconeogenic precursor, offsetting some of the muscles release of amino acids to provide glucose.

Peter, what fast length are you talking about? I'm not aware of any studies which show any catabolic effect on muscle (providing adequate protein is consumed at least every 48 hrs). Mike Eades addressed this possibility in his initial blog on IF. The 'free amino acid pool' lasts up to forty eight fasted hours. Plus you get the anabolic hgh and muscle growth gene expression benefits of fasting. Benefits which you miss out on if you 'break' fast with leucine.

Stuart.

[Garrett Smith]

The main reason for fasting is protein & amino acid turnover, so inhibiting those processes would not benefit the end goal.

Or you could try it and report back to us with your results...you could be onto something and you won't know unless you try it out!

[Peter Borden]

http://jn.nutrition.org/cgi/reprint/106/2/230.pdf

I know this is rodents and may not apply to humans. But interesting.

Effects of leucine and phenylalanine supplementation during intermittent periods of food restriction and refeeding in adult rats.
Donato J Jr, Pedrosa RG, de Araújo JA Jr, Pires IS, Tirapegui J.

Department of Food and Experimental Nutrition, Faculty of Pharmaceutical Sciences, University of São Paulo, Av. Professor Lineu Prestes, 580, bloco 14, 05508-900, São Paulo, São Paulo, Brazil.

Although many studies have shown that amino acid ingestion acutely stimulates protein anabolism, only few studies have investigated whether long-term supplementation promotes changes in body composition. We therefore tested the hypothesis that l-leucine (LEU) and l-phenylalanine (PHE) supplementation might have a positive impact on the body composition of rats submitted to intermittent periods of food restriction and refeeding (weight cycling or WC). The WC protocol comprised three cycles, each consisting of 1 week of 50% food restriction followed by 2 weeks of ad libitum ingestion. The groups submitted to WC ingested the control diet (WC-CON) or the diet supplemented with LEU+PHE (WC-AA). A pair-fed group receiving the control diet (PF-CON) was used as a reference for the effects of WC. Although food intake was the same in all groups, higher body weight and energy efficiency were observed in the WC-AA group compared to the PF-CON and WC-CON groups although not significantly in relation to the latter. These results were the consequence of a significant increase of lean body mass and body protein content in the WC-AA group compared to the PF-CON and WC-CON groups. The WC-CON and WC-AA groups presented 36.1% and 18.9% more body fat, respectively, than the PF-CON group but this difference was not significant. Neither fasting insulin nor glucose concentration nor postprandial insulin secretion was significantly affected by the supplemented diet. In conclusion, supplementation with LEU+PHE improved the body composition profile of rats submitted to WC, mainly by increasing lean body mass and body protein content.

[Garrett Smith]

That's an impressive study, even if only in rats. I'm interested to see the leucine dosing by bodyweight.