Why can’t you eat past a certain time at night if you have to take a blood test the next morning?

Question

I am supposed to take a blood test in the morning and my doctor told me that I have to do it on an empty stomach, and can’t eat anything after 9pm. I understand how alcohol, for one, could impact blood test results but why food? Asking cause I’m hungry 🙁

In: Biology

Answer 1

Just to piggyback onto OP’s question.

Does fasting *too* long also affect the test? Usually they want you to not eat or drink (except for water) for 12 hours. If you go 17 hours before the test would it also skew the results? When they say 12 hours is that a hard fast rule?

Edit: (Basic cholesterol /triglyceride tests)