pete69
10-14-2006, 04:06 PM
I've been really interested in trying intermittent fasting, but am worried about losing muscle that i've worked hard to build up. In starvation studies, there is an initially rapid loss of muscle through gluconeogenesis of the BCAA's, taken from muscle tissue. Over a 3 week period, as the body adapts to ketosis and it's glucose requirements lessen, this drops to a very low level of muscle breakdown.
The BCAA's (leucine, isoleucine and valine), as well as alanine and glutamine are the main AA's that are released into the blood. Some studies have suggested infusion of the BCAA's have a muscle sparing effect during starvation as well as with fasting hospital patients. I've been contemplating doing a diet of fasting every other day, with the inclusion of BCAA's and glutamine on fasting days, to prevent the depletion of amino acids from muscle, while still getting all the other physiological effects of fasting.
The following studies are infusion studies with BCAA's, but since BCAA's are rapidly absorbed when ingested orally, it seems they would provide similar benefit in sparing muscle while fasting.
Nitrogen sparing induced early in starvation by infusion of branched-chain ketoacids.
* Sapir DG,
* Walser M.
The alpha-ketoanalogues of the branched-chain amino acids were administered to fasting subjects to determine whether or not they promoted nitrogen sparing. Two fasting studies were carried out in each subject. During the first week of one of the two fasts 4.7 g of a mixture of the alpha-ketoanalogues of valine, leucine, and isoleucine were infused daily. No infusions were administered during the other fast, which served as a control. Urinary urea and calculated total urinary nitrogen were significantly lower during both the week of infusions and the ensuing week of fasting after the infusions were discontinued. Immediately after ketoacid infusions, plasma branched-chain amino acids, including allosioleucine, rose, while alanine and several other amino acids (but not glutamine) fell. There were no differences between the two fasts with respect to ketone bodies, free fatty acids, glucose, insulin, or glucagon concentrations. We conclude that branched-chain ketoacids spare nitrogen early in fasting and that this effect persists after they are metabolized.
Infusion of the Branched Chain Amino Acids in Postoperative Patients: Anticatabolic Properties
Herbert Freund, Herbert C. Hoover, Jr., Susan Atamian, and Josef E. Fischer
Postinjury metabolism is characterized by breakdown of muscle protein as substrate for energy production and gluconeogenesis and by the resultant loss of lean body mass and weight loss. The branched chain amino acids (BCAAs) which are principally oxidized by the skeletal muscle have been implicated in recent in vitro and in vivo studies as having special anticatabolic and regulating effects in skeletal muscle. We studied the anticatabolic effects of the BCAAs in 35 patients undergoing operative injury of moderate severity. In a prospective randomized and blinded manner patients were infused for five days starting immediately after surgery with either 5% dextrose or 5% dextrose with an amino acid solution containing 22, 35 or 100% BCAAs. All patients survived and there were no major postoperative complications. Mean hospital stay was 17 days for patients receiving amino acids and 19 days for patients receiving 5% dextrose only (p = ns). All three groups receiving amino acid solutions were in nitrogen equilibrium or in a slight positive nitrogen balance, while the group receiving 5% dextrose only was in a mean negative nitrogen balance of 6.6 ± 0.6 gN/day. The differences between the three groups receiving amino acids were slight and not significant. Weight loss was 2 ± 0.7 kg in the 5% dextrose group, 1 ± 0.7 kg in the 22% BCAAs group, 0.5 ± 0.5 kg in the 35% BCAAs group and the 100% BCAAs group gained 0.4 ± 1.8 kg. Blood chemistries in the different groups and during the study period remained within normal limits except for ammonia levels rising significantly in the 5% dextrose group and SGOT levels rising in the 22% and 35% BCAA groups. With mild variations the plasma amino acid patterns in all groups were similar to the normal pattern, even in the 100% BCAAs group receiving an unbalanced amino acid solution, suggesting the complete cessation of amino acid efflux from muscle, the muscle depending solely on the exogenous supply of BCAAs to satisfy its metabolic requirements. The results suggest that early nutritional suppport in the postoperative period will result in nitrogen equilibrium and that the infusion of the three BCAAs only in the postoperative state is as effective in preventing muscle catabolism as other more balanced amino acid solutions. In the postinjury state balanced amino acid solutions rich in BCAA may prove beneficial.
The BCAA's (leucine, isoleucine and valine), as well as alanine and glutamine are the main AA's that are released into the blood. Some studies have suggested infusion of the BCAA's have a muscle sparing effect during starvation as well as with fasting hospital patients. I've been contemplating doing a diet of fasting every other day, with the inclusion of BCAA's and glutamine on fasting days, to prevent the depletion of amino acids from muscle, while still getting all the other physiological effects of fasting.
The following studies are infusion studies with BCAA's, but since BCAA's are rapidly absorbed when ingested orally, it seems they would provide similar benefit in sparing muscle while fasting.
Nitrogen sparing induced early in starvation by infusion of branched-chain ketoacids.
* Sapir DG,
* Walser M.
The alpha-ketoanalogues of the branched-chain amino acids were administered to fasting subjects to determine whether or not they promoted nitrogen sparing. Two fasting studies were carried out in each subject. During the first week of one of the two fasts 4.7 g of a mixture of the alpha-ketoanalogues of valine, leucine, and isoleucine were infused daily. No infusions were administered during the other fast, which served as a control. Urinary urea and calculated total urinary nitrogen were significantly lower during both the week of infusions and the ensuing week of fasting after the infusions were discontinued. Immediately after ketoacid infusions, plasma branched-chain amino acids, including allosioleucine, rose, while alanine and several other amino acids (but not glutamine) fell. There were no differences between the two fasts with respect to ketone bodies, free fatty acids, glucose, insulin, or glucagon concentrations. We conclude that branched-chain ketoacids spare nitrogen early in fasting and that this effect persists after they are metabolized.
Infusion of the Branched Chain Amino Acids in Postoperative Patients: Anticatabolic Properties
Herbert Freund, Herbert C. Hoover, Jr., Susan Atamian, and Josef E. Fischer
Postinjury metabolism is characterized by breakdown of muscle protein as substrate for energy production and gluconeogenesis and by the resultant loss of lean body mass and weight loss. The branched chain amino acids (BCAAs) which are principally oxidized by the skeletal muscle have been implicated in recent in vitro and in vivo studies as having special anticatabolic and regulating effects in skeletal muscle. We studied the anticatabolic effects of the BCAAs in 35 patients undergoing operative injury of moderate severity. In a prospective randomized and blinded manner patients were infused for five days starting immediately after surgery with either 5% dextrose or 5% dextrose with an amino acid solution containing 22, 35 or 100% BCAAs. All patients survived and there were no major postoperative complications. Mean hospital stay was 17 days for patients receiving amino acids and 19 days for patients receiving 5% dextrose only (p = ns). All three groups receiving amino acid solutions were in nitrogen equilibrium or in a slight positive nitrogen balance, while the group receiving 5% dextrose only was in a mean negative nitrogen balance of 6.6 ± 0.6 gN/day. The differences between the three groups receiving amino acids were slight and not significant. Weight loss was 2 ± 0.7 kg in the 5% dextrose group, 1 ± 0.7 kg in the 22% BCAAs group, 0.5 ± 0.5 kg in the 35% BCAAs group and the 100% BCAAs group gained 0.4 ± 1.8 kg. Blood chemistries in the different groups and during the study period remained within normal limits except for ammonia levels rising significantly in the 5% dextrose group and SGOT levels rising in the 22% and 35% BCAA groups. With mild variations the plasma amino acid patterns in all groups were similar to the normal pattern, even in the 100% BCAAs group receiving an unbalanced amino acid solution, suggesting the complete cessation of amino acid efflux from muscle, the muscle depending solely on the exogenous supply of BCAAs to satisfy its metabolic requirements. The results suggest that early nutritional suppport in the postoperative period will result in nitrogen equilibrium and that the infusion of the three BCAAs only in the postoperative state is as effective in preventing muscle catabolism as other more balanced amino acid solutions. In the postinjury state balanced amino acid solutions rich in BCAA may prove beneficial.