What Causes Elevated ALT Levels?

Hi while taking medication for gout in October last year 2010, the doctor thought it best to check my liver enzymes before prescribing the relevant NSAID. At that time I showed slightly raised AST/ALT levels but not enought to prevent prescription of NSAID (AST-42 / ALT-65). After about taking NSAID for a little more than a month and periodic gout attacks in between, I took the last prescription in Dec 2010 for around one week. In Jan during a follow up when we checked on the liver enzymes, the AST had slightly come down but ALT was up to 70. I also took Colchicin from Jan till around Feb 15. Now, last week (Mar 2011) I had a retest on my liver but with all functions - in this AST is 57 and ALT is 99. However, all other liver function blood tests are absolutely within normal range. Is this something to be concerned about? How do I reduce AST and ALT? I am currently taking an herbal drug called LEGALON which is said to prevent liver damage. I have also had an abdominal USG done at which time other than a gassy colonic area I was shown to have grade 2 fatty liver. I used to drink a lot - but in July 2010 I quit alcohol and did so until Dec 2010. I restarted in Jan 2011 but my consumption is minimal - maybe a couple of pegs per week. I am also on a diet and exercise regularly for 1.5 hrs everyday. I am overweight / obese at 115kgs. I am concerned about the trend in my ALT from 65 to 70 to 99 when my diet has been brought to some level of control and coupled with exercise as well. I have increased proteing intake and am told this could be a reason as well? Could you throw any light on this?