Guide

Not always—many CT scans allow normal eating, but contrast or sedation often calls for a short fast set by the imaging center.

No, fasting usually isn’t needed for celiac antibody blood tests; keep gluten in your diet until testing is done.

Yes, fasting is commonly requested for 8–12 hours before this blood draw, with plain water allowed unless your lab tells you otherwise.

Many lipid tests can be done without fasting, but fasting for 9–12 hours is still used when triglycerides need a clearer reading.

Yes—most people stop solid food the day before and stop clear liquids a few hours before, based on the exact cutoff your clinic gives.

No—most cortisol blood draws don’t require fasting, yet morning timing, meds, and recent workouts can shift results more than food does.

You’ll fast 8–12 hours for fasting glucose or an oral tolerance test; A1C and random glucose tests don’t require fasting.

No—most PSA blood tests don’t require fasting, unless the order includes other labs that do.

No fasting is needed for this blood test, so you can eat and drink as usual while avoiding a few activities that can nudge PSA for a day or two.

Alcohol isn’t outright off-limits with GLP-1 medicines, but it can worsen nausea and swing blood sugar, so smaller servings with food tend to sit better.