For the last year I haven't been able to regain any reasonable amount of fat to help hide my tendons and ligaments on my hands and wrists. I took acetyl l carnitine out of desperation to help gain energy but this may have contributed to my biotin deficiency. Once I added mb12 then the fat really went away. Biotin is a component of the acetyl CoA carboxylase enzyme. This enzyme converts acetyl coA to Malonyl-CoA. http://en.wikipedia.org/wiki/Acetyl-CoA_carboxylase Malonyl-CoA is a highly-regulated molecule in fatty acid synthesis; as such, it inhibits the rate-limiting step in beta-oxidation of fatty acids. Malonyl CoA inhibits fatty acids from associating with carnitine by regulating the enzyme carnitine acyltransferase, thereby preventing them from entering the mitochondria where fatty acid oxidation and degradation occur. So to limit the use of the carnitine induced oxidation, malonyl-CoA is trying to prevent the fatty acids from being oxidized. The biotin is used to help create the malonyl CoA. It sounds like that this reaction would be enough to create a biotin deficiency honestly. You are feeding fatty acids into b oxidation thru the use of carnitine all the while your body may be trying to hold onto the fatty acids thru the use of a biotin related enzyme. Another point to make is the reactions with pyruvate. Pyruvate carboxylase is a biotin dependent enzyme that is used in the first chain of gluconeogenesis reactions. This probably isn't the best reaction for us to make, but I think because of the high ketones that I saw on my test results it is probably used extensively just trying to survive sometimes. But, the drawback too is this enzyme is used to help control blood glucose levels and other things. I doubt it would explain my hypoglycemic symptoms but it could play a role in it.