Abstract: A method for measuring more accurately Fatty Acids and Essential Fatty Acid (EFA) Deficiencies (EFAD). The invention includes a disease diagnostic method for the diagnosis of lipid and fatty acid biochemical abnormalities found through the analysis of tissues of a test subject, deriving indices of lipid and fatty acid biochemical status, and analytically comparing patterns or domains obtained from indices of a subject with similar indices derived from tissues of subjects with normal and abnormal biochemistry, for the purposes of diagnosing abnormalities. A specific mixture of nutrients (test mixture), prepared according to this invention, is given to a test subject to modify the tissue composition of said test subject in order to verify or modify a diagnosis, including mixtures of w3 and w6 fatty acids. Another specific mixture of mixture of nutrients (treatment mixture), prepared according to this invention, is given to a test subject to correct lipid and fatty acid abnormalities found in said test subject.