It's very hard to find good information on Fatty Liver disease in reptiles.  Even my Mader's Reptile Medicine and Surgery (first edition) didn't discuss this problem.

   Fatty liver disease or hepatic lipidosis, is really is a symptom of other disorders that might affect reptiles.  It's a metabolic disease. The liver is a very important organ - and when it starts to fail other organs start to fail, including the heart.

       80% of the liver is made up of Hepatocytes which are the chief functional cells of the liver and perform an astonishing number of metabolic, endocrine and secretory functions. Roughly 80% of the mass of the liver is contributed by hepatocytes. 

     Often, during necropsy, when an animal is diagnosed as passing away from a secondary cause of fatty liver disease the hepatocytes cells are found to have fatty changes.   Occasionally during necropsy, a pathologist might find signs of Xanthomatosis, which is a condition in which fatty deposits occur in various parts of the body. These fatty deposits are called xanthomas or xanthomata and appear as yellowish firm nodules in the skin. Xanthomas are in themselves a harmless growth of tissue. However, they frequently indicate the presence of underlying diseases such as diabetes and disorders of fats (lipid disorder or hyperlipidemia). Under the microscope, a xanthoma consists of lipid-laden foam cells. These cells, termed histiocytes, contain lipid material in their cytoplasm (the nonnuclear zone of the cell).

   Long periods of anorexia (not eating) can cause the liver to metabolize fats poorly once the animal begins to eat again. when the liver can't metabolize fats in the diet properly it becomes fatty and begins to function poorly.

   My gut feeling is that with our reptiles, extended periods of anorexia is the leading cause of fatty liver disease.  When our animals become sick with parasite infections or when they become gravid they tend to not eat.  If they remain sick for long periods I think the chances of them developing some liver problems when they start to eat again is good- especially if they are being fed diet items that are high in fat.

    My suggestion is that when your reptile is recovering from an illness that has caused it to stop eating for a period of time, please start the herp on a low fat, low protein diet.  

    Many people give their reptiles food items that are known to be high in fat- such as  waxworms when they aren't eating well or when they are recovering from illness. They often do this in an attempt to put the weight back on the animal quickly, but what they really might be doing is harming the reptiles liver.

  Please start off with items such as earthworms or low fat, low protein slurries until the animal is starting to do better.  Then gradually get it back to it's normal diet.  If we are careful about how we start them back on food we may lessen the chances of them developing liver problems simply from beginning to eat again.