We already know that water’s good for you. Pouring plenty of H₂O may help lower your blood pressure and prevent kidney infections.
But is it OK to drink water when you’re supposed to have an empty stomach? You’ve got questions, we’ve got answers. Here are the deets about whether you can drink water while you’re fasting.
Can you drink water when fasting?
It’s generally OK to drink water while you’re fasting for blood tests, an intermittent fasting diet, and some medical procedures. Surgeries typically restrict water up to 2 hours before, though.
Having something (even water) in your belly when you’re under general anesthesia could cause major probs. Your body loses its natural reflexes when you “go under,” and you might end up vomiting.
That’s why it’s so important to connect with your healthcare professional if you have any questions about your diet for an upcoming test or surgery.
Unless your healthcare professional tells you otherwise, you’re generally allowed to drink water when you’re fasting for a blood test.
Not every blood test requires fasting, but it’s *really* important to follow this rule. Eating before a fasted test could give you inaccurate results.
Common blood tests that require fasting include:
- liver function test (8- to 12-hour fast)
- basic metabolic panel (8- to 12-hour fast)
- glucose test (overnight 8- to 10-hour fast)
- vitamin B complex test (overnight 8- to 10-hour fast)
- renal function panel (8- to 12-hour fast)
- gamma-glutamyl transferase test (overnight 8- to 10-hour fast)
- lipoprotein panel (8- to 12-hour fast)
- cholesterol test (up to 14-hour fast)
- triglyceride level test (up to 12-hour fast)
- serum iron test (up to 12-hour fast)
- vitamin B12 tests (6- to 8-hour fast)
When can I eat again after a blood test?
You can eat right after completing your blood test. Feel free to pack your fave munchies before heading to your appointment!
The American Red Cross recommends eating iron-rich foods after a blood draw to help your body recover faster.
Intermittent fasting (IF) is a diet when you alternate between eating and not eating for a given period of time (usually 8 to 16 hours each day). Unlike other diets that restrict what you eat, IF focuses on when you eat.
A research review showed that fasting may come with health benefits, like lowering your blood sugar and insulin levels.
Water doesn’t affect your blood sugar or insulin levels. So, you can drink it while on IF, but there is one exception: dry fasting. That’s a type of IF when you don’t eat or drink anything for a period of time. And nothing means, nothing. Not even water.
FYI: It’s a good idea to talk with your healthcare professional before trying IF. But it’s super important to clear it with your healthcare professional if you have diabetes. Why? Because IF can affect your blood glucose levels.
The type of medical procedure you’re getting will determine whether you can have water beforehand. Your healthcare professional should give you specific instructions on what’s OK for you to eat and drink, and when. Feel free to reach out and ask them if you have any questions.
Procedures with a general anesthetic
If you’re heading to surgery, your healthcare professional will prob have you fast for 8 to 12 hours. A research review showed that you might be able to drink water when fasting for a surgery, but no closer than 2 hours before. Again, this can vary depending on your situation. So, check with your healthcare professional if you’re unsure.
Longer, more invasive procedures typically use general anesthesia, like:
- back surgery
- gallbladder removal
Procedures with a local anesthetic
For a local anesthetic, drinking water and eating before your procedure is usually OK.
Less invasive procedures tend to use local anesthesia, like:
- dental work
- mole removal
- skin biopsy
- breast biopsy
Bottom line. You’re generally allowed to drink water until 2 hours before surgery. But, you should always follow your healthcare professional’s directions before a procedure and reach out to them if you have questions.
Thirsty for more than just plain water? We’ve got you! The following sips are generally safe to drink when fasting, and will keep you hydrated while your stomach does its thing. Raise your glass, and say cheers!
Drinks that won’t break your fast (other than dry fasting):
- black coffee (not allowed before some blood tests/medical procedures)
- unsweetened tea
- flavored water (sugar free/calorie free)
- sparkling water (sugar free/calorie free)
- lemon water (sugar free/calorie free)
- bone broth (not allowed before some blood tests/medical procedures)
Pro tip: Always be sure to check with your healthcare professional about what counts as a clear liquid, and what you can drink before your surgery or procedure. If you’re going for a lab test that requires fasting or you’re trying to maintain ketosis, all liquids should be clear and sugar free/calorie free.
- It’s fine to drink water before taking a blood test, unless your healthcare professional says not to.
- You’re allowed to drink water during intermittent fasting. The only exception is dry fasting.
- Dry fasting restricts all foods, and liquids (including water) during certain time periods. It can lead to dehydration. So, be careful.
- If you’re prepping for a surgery, or other medical procedure, you’ll prob need to fast for 8 to 12 hours.
- Depending on the type of procedure, you can drink water when fasting until 2 hours before your surgery.
- You can typically sip on water and other calorie-free drinks like black coffee, unsweetened tea, and lemon water while fasting.