Welcome to HealthcareMagic forum.
The rise in ALT is more specific to your liver function. It can rise even in people who do not drink alcohol and are not on any drugs too. the causes being Viral hepatitis
fatty liver,Autoimmune hepatitis
, Herbal toxicity,Genetic liver diseases,Liver tumors
Regarding the GGT values, they are more indicative of a gall bladder disease
as in cholestatic diseases,like gall bladder stones, infections of the same,primary biliary cirrhosis
as in your case it could be a fatty liver or even a non alcoholic fatty liver disease to be more specific
It needs to be evaluated further and treated accordingly with simple diet management and few drugs if needed
Wishing you good health.