A fatty acid oxidation disorder is a condition that impairs the body's ability to oxidize the fatty acids into energy. This can lead to serious problems affecting the heart, liver, eyes, and general muscle development. These disorders can remain hidden, until brought on by high fever or periods of fasting, both of which alter the rate of metabolism within the body. Once brought on, patients may experience altered consciousness, decreased activity, and can conceivably progress to lethargy. They often include repeated bouts of vomiting. Early signs can include carnitine deficiency or poor (low tone) muscle development.