R-ALA is not a carb source it is used in conjunction with carbs. From what I have read and believe: as we all know simple carbs cause an insulin spike, this insulin spike causes glucose and other nutrients to be more readily uptaken by all body cells, including fat and muscle cells. Adding R-ALA channels this glucose into muscle cells, only, thereby, evading fat cells in the process so no "carbs/glucose" can be stored as fat until all of your glycogen stores are full.
I use ala/biotin with every meal containing carbs for this reason.
I believe for every 40g of carbs you ingest, you require at least 100g R-ALA for this process to be efficient. Many CKDers even claim that they can eat carbs and still remain in ketosis via the use of ALA.