The same as if you did not eat or drink a lot of water.
How much did you drink and when, and when is the test

I found it easier to avoid the substances and eliminate the worry of the consequences.

As Fr_Chuck asked.. how much did you drink and when is the test?

Having more water probably would help though, if your worried, as would lots of exercise, helps speed up the bodies processes...
Otherwise, I'd personally blame some cough syrup, or a dodgy friend (I asked him for NON alcoholic cider... ) or some other bogus excuse...
Unless of course you're a pilot, or have some other good reason to NOT have alcohol in your blood, in which case, shame on you... :)

Bogus excuses are no way to handle this.
These people do this every day and are not fooled easily.

When you are not suppose to have alcohol in your system , they will tell you it is up to you to know what is in any medication you take.
If it contains alcohol you are not suppose to take it unless ordered by a doctor and you notify them with proof.

It will usually go harder for you if you try to bs them.

Just don't do it.