Here are some studies that might relate to why eating a very low carb /zero carb diet is good for this condition:
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1867088/Mitochondrial Biogenesis in the Anticonvulsant Mechanism of the Ketogenic Diet
These data show that a calorie-restricted KD enhances brain metabolism. We propose an anticonvulsant mechanism of the KD involving mitochondrial biogenesis leading to enhanced alternative energy stores.
http://linkinghub.elsevier.com/retrieve/pii/S0304416509000026The effects of a ketogenic diet on ATP concentrations and the number of hippocampal mitochondria in Aldh5a1?/? mice
http://www.mitochondrial.net/showabstract.php?pmid=19049599"We found a coordinated up-regulation of transcripts encoding energy metabolism enzymes and a dramatic 46% increase in the density of mitochondria observed in neuronal processes."
http://www.mitochondrial.net/showabstract.php?pmid=15048898The ketogenic diet increases mitochondrial uncoupling protein levels and activity.
This above is interesting considering one measure of CFS is a certain level of mitochondrial dysfunction:
http://www.ijcem.com/812001A.htmlWith the consent of each of 71 patients and 53 normal, healthy controls the 5 factors have been
collated and compared with the Bell Ability Scale. The individual numerical factors show that patients have different combinations of
biochemical lesions. When the factors are combined, a remarkable correlation is observed between the degree of mitochondrial
dysfunction and the severity of illness (P<0.001).
So, to me it would appear that two important areas of exploration for CFS/ME would be (1) enhancing the function of the HPA axis and thyroid gland through eating glands and/or finding ways to stimulate their activity and (2) eating a very high fat, low carb diet so as to increase the density and function of the mitochondria