I may be wrong, but it sounds as if they suspect heavier than recommended alcohol consumption with subsequent damage to your liver. Not having a beer for two weeks would not get rid of any possible indications as damage, if it is present, takes a bit of time to repair. A similar thing happens with poorly controlled diabetes - a HbA1C test will show the effect of blood sugar levels over the previous month so sticking rigidly to the diet for a week or so before the test in the hope of achieving low levels won't work - it needs to be adhered to all the time. Hope that helps.