CD4 and myalgic encephalomeyelitis/chronic fatigue syndrome: Positive studies: (378–389) In healthy people, acylcarnitine levels and, hence, ß-oxidation of fatty acids (main source of ATP during aerobics) rises with exercise. But acylcarnitine falls with exercise in ME/CFS (390). CD4+, CD8+, and NK cells rely more on fatty acid oxidation for generating ATP in people with ME/CFS vs. controls (302).