Is Unusual Weight Gain A Symptom Fatty Liver?

I had bloods test done twice with 3 day interval in between. For my first test, i had an alt of 65 (normal is 10 to 39) at my lab and 32 ast(upper end but normal at my lab). I did not have billirubin tested Following this I had abdominal ultrasound done 3 days after and was normal including liver although due to apparent bowel gas pancreas is not entirely clear but from what seen there is no problem. I then had another blood test on same day of ultrasound, tested negative for hepatitis B and C and this time tested for billirubin. My alt this time was 48 and ast 25 which was lower than before but billirubin was 1.8 (norm is 0.1 to 1.0) In my first blood test my wbc was slightly high 11.14x 10^3 , platelet and everything normal includig individual wbc types. Recently i just finished my exams and during this period I did no exercise and ate quite a lot gaining 6kg in around 1 or 2 month, could this be the cause? Could it be fatty liver although not obvious in ultrasound? I am considering to do an abdominal ct, would that be necessary. If helpful I am 20 years old. Thank you