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'Can I Drink Coffee While Fasting?'

By Elizabeth Hanes, BSN, RNJuly 6, 2020
From the WebMD Archives

I heard the same question almost every time I gave pre-op instructions to a patient: Once I got to the part about “nothing to eat or drink after …”, nearly every one of them would look at me in anguish and ask, “Does that mean no coffee??”

I feel you.

As a connoisseur of caffeine, myself, I understand that fasting can be difficult enough without giving up coffee to do it. And the good news is: sometimes you don’t have to!

The answer to this question depends on the type of fasting you’re doing. Can you drink coffee while doing …

Pre-surgical fasting? No, you absolutely may not drink coffee (or water – or beverages of any kind) after the cut-off time you’re given. That’s because the medications used in general anesthesia make it easy for stomach contents to regurgitate into the esophagus, where they can be inhaled. Not good. So, you should never eat or drink anything for several hours prior to a surgery with general anesthesia.

Fasting before blood tests? Yes, in most cases, you may drink black coffee before a “fasting” blood test (or black tea if that’s your preference). These beverages generally will not affect the results of common fasting lab tests, like cholesterol (lipid panel), metabolic panel or blood glucose. To be safe, though, you should ask your doctor or call the lab in advance to see if you can enjoy your morning java fix before you get your blood drawn. And what happens if you cheat and add cream or sugar to your coffee before a fasting lab test? Well, it can greatly alter the results, so be sure to alert the lab tech and your doctor. You may be asked to have the blood drawn all over again.

Intermittent fasting? Yes, you can drink black coffee (or tea or pretty much any non-caloric beverage) if you’re doing intermittent fasting (IF). IF is based on a concept called “time-restricted feeding” in which you take in calories only during a small window of time each day. But black coffee does not contain calories, so drinking it won’t break your fast. Now, if you add cream or sugar, then you’ve blown your fast because those things contain calories.

When you’re asked to fast for medical reasons, it’s important to follow your doctor’s specific instructions – even if that means no coffee – because breaking the fast could seriously jeopardize your health. But if you’re fasting to lose weight or just because you think it’s a healthier lifestyle, you don’t have to give up coffee. In fact, you can consider it a little indulgence that might help you get through the fasting period more easily!

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