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    We often get asked a lot of questions about what you can drink while intermittent fasting, and apple cider vinegar (ACV) — thanks to its celeb endorsements — is a regular in our Q&As. 

    Sipping on apple cider vinegar during intermittent fasting? We’ve got the lowdown on whether it’s a fasting friend or foe.

    Can you drink apple cider vinegar while fasting, or does apple cider vinegar (ACV) break a fast? And if you can drink it, what are the benefits of apple cider vinegar while fasting? Is it as helpful for general health and weight loss as some high-powered names suggest? 

    Let’s dive into what the experts say about apple cider vinegar and fasting. If you’re new to the concept of intermittent fasting, you might want to check out our intermittent fasting for beginners guide first!

    Key takeaways

    • Apple cider vinegar + intermittent fasting can go together and won’t break your fast if you don’t overdo it.
    • … But the evidence with apple cider vinegar, at least so far, is pretty limited in terms of its potential benefits.[1]  
    • Drinking a tablespoon or two per day has been suggested to support weight loss and blood sugar control.[2,3]
    • Due to its high acidity levels, ACV can interact with certain medications, cause digestive issues, or erode tooth enamel.  
    • If you want to try ACV as part of your fasting meal plan, we recommend diluting a tablespoon in a large glass of water. 

    So, will apple cider vinegar break a fast?

    Let’s address the biggie right away: does drinking apple cider vinegar break a fast? 

    The short answer is (drum roll): no, not if you limit it to a tablespoon or two. 

    More good news: it’s unlikely you’d want to guzzle a glass of the stuff anyway. It can be quite, shall we say, potent in taste and smell, so not everyone digs it. 

    And if you’re wondering, “Can I take apple cider vinegar while water fasting?” we don’t recommend water fasting in general. It’s pretty tough on your body, and there’s limited evidence to prove its efficacy. 

    How much ACV is advised while fasting?

    A tablespoon of apple cider vinegar contains only three calories. For a comparison point, the same amount of balsamic vinegar contains 14 calories.

    While the scientific jury is still out in terms of exactly and definitively how many calories will break a fast, it’s generally accepted that fewer than ten calories won’t spike your insulin levels and knock your body out of its fasted state. That’s why a tablespoon or two of apple cider vinegar while fasting is on the table (if you want it to be!). The only time ACV will break a fast is if you have more than a couple of tablespoons. 

    We also recommend diluting that tablespoon or two in a tall glass of water. It may not only help mitigate some of the risks of drinking ACV (we’ll get into those later), but it’s also a heck of a lot more palatable. (Straight shots of ACV? Bleh!)

    When is the best time to drink it?

    When to drink apple cider vinegar while intermittent fasting depends on your personal preferences.

    Having ACV in the morning or during your fasting window may reduce appetite and help you feel fuller for longer,[4] which may support weight loss and fend off hunger pains and cravings. On the other hand, drinking ACV with meals has been shown to have the potential to benefit metabolism and digestion in certain people,[2] but more research is needed to back this one up.

    As with intermittent fasting itself, there’s no universal best fit, so you may want to experiment with different timings and see what feels best for you.

    Apple cider vinegar (ACV) — What is it?

    Like its name suggests, apple cider vinegar is basically a more acidic evolution of apple cider. It’s made by fermenting apple juice and sometimes scraps of apple with yeast. 

    Sadly, it doesn’t exactly retain any apple cider flavors as we know them — no warming fall spices are involved! And it’s definitely not meant to be consumed by the glass as you might with actual cider. 

    As the cider ferments, bacteria break down carbs, sugar, and alcohol and produce acetic acid. This byproduct of fermentation is what gives ACV its potency,[5] both in terms of its classic vinegar taste and its potential health benefits. 

    We say “potential” with an extra dose of caution here. While ACV in small amounts generally won’t do any harm, existing evidence as to its benefits is still pretty limited. As with any dietary change-up you might be considering — especially when intermittent fasting is involved — we always recommend checking in with your primary care provider before adding or subtracting to your daily routine, too.  

    You can also tag us in to help with menu planning around what to eat while intermittent fasting and what breaks a fast. Just take our Simple quiz to give us the lowdown on you and what you want to accomplish with your fast, and we’ll get started on your suggested shopping list. 

    What does it consist of?

    So, we already know a tablespoon (or roughly 14.9 grams) of ACV serves up about three calories, but what does that spoonful of acetic acid actually look like in terms of nutrition? 

    It’s actually pretty simple: it’s just a tiny bit of three things — sugar, potassium, and sodium. 

    A tablespoon of apple cider vinegar contains no fat, protein, dietary fiber, cholesterol, or vitamins. It’s made up solely of 0.1 g of sugar (carbs), 11 mg of potassium, and 1 mg of sodium. 

    Put simply, a tablespoon or two of ACV won’t make even the slightest dent in your calorie or nutrient intake. 

    Health benefits of drinking apple cider vinegar while intermittent fasting

    A plate full of possibilities! Discover how apple cider vinegar may enhance your fasting experience — from reducing cravings to supporting weight loss. The science is on the table.

    Like we mentioned, there isn’t a lot of evidence that speaks to the health benefits of apple cider vinegar + fasting. 

    For example, there’s some anecdotal evidence that ACV may benefit digestion by improving levels of stomach acidity or reduce bloating by balancing the bacteria in the gut microbiome,[5] but there aren’t any studies to back up these claims yet. Plus, most existing studies are limited in scope and scale, so it’s worth taking these benefits with a grain of “still more research needed” salt. 

    That said, here’s what we know from the science so far. 

    Reduce body fat 

    Acetic acid may boost your ability to tap into stored body fat for energy by reducing your blood glucose levels and improving glycemic parameters.[2,6] 

    Boost metabolism 

    ACV may improve glucose metabolism and insulin sensitivity.[2] (FYI, we often get asked, “Does intermittent fasting slow metabolism?” but actually, fasting in general can support a better metabolic rate, too![7]

    Decrease hunger and cravings 

    Apple cider vinegar may function as an appetite suppressant and help you feel satiated,[4] which is great for any pesky stomach grumbles during a fasting window.

    Support weight loss

    Apple cider vinegar may benefit weight loss,[2] but more research is needed. At this stage, we can’t claim that there is anything magic about taking ACV. To lose weight, you still need to establish an energy restriction, which intermittent fasting can help you achieve. 

    Possible drawbacks of drinking apple cider vinegar while fasting

    Unfortunately, just because you can have apple cider vinegar while fasting doesn’t guarantee that apple cider vinegar during a fast is a good match for you personally. For most people, it’s not harmful to have a tablespoon or two of ACV, with or without a fast involved, but there are still some potential side effects to consider. 

    Interactions with medications

    You might be familiar with the warnings to avoid alcohol when taking antibiotics or operating heavy machinery after a sleeping pill, but all sorts of things might impact the medications you’re taking. That’s one reason why it’s so important to chat with your healthcare provider before modifying your eating habits. In this case, ACV may impact medications like diuretics, laxatives, and insulin.[1]

    Tooth erosion

    Apple cider vinegar is pretty acidic (it has a pH level of around 3 on a scale where 1 is the highest), and acid can eat away tooth enamel [8] … which doesn’t regrow. It may not be as dramatic as horror film uses of acid as a dissolving agent, but frequently drinking ACV (especially undiluted) can erode your enamel and leave you with sensitive teeth.

    Digestive issues

    Beyond the fact that ACV isn’t the most appealing of tastes and may invoke nausea,[9] its high levels of acidity can also throw off the balance of acid and bacteria in your gut. In turn, this imbalance can lead to cramps, bloating, diarrhea, or stomach ulcers. 

    Risk for low potassium

    If you have low potassium levels and consume ACV in large quantities (much more than a couple tablespoons), it could make the condition worse, as seen in this single patient. While we can’t draw conclusions from such a small study, airing on the side of caution and liaising with your healthcare provider before making any changes is always the best move. 

    Tips on taking apple cider vinegar during a fast

    Unlock the benefits of apple cider vinegar during your fast with Simple’s tips. Dilution, timing, and hydration — it’s all in the details!

    Simple’s number one tip for any fast is to start by speaking with your healthcare provider. Whatever you eat or drink, intermittent fasting isn’t safe or right for everyone, especially if you: 

    • have type 1 diabetes;
    • are pregnant, breastfeeding, or trying to conceive; 
    • are prescribed medication (like hypertensives or any medications that need to be taken with food);  
    • have a history of or are currently diagnosed with disordered eating;
    • have a BMI of less than 18.5; or
    • are 18 and under or 80 years or older.

    When it comes to integrating ACV into your fast, here are our recommendations. 

    1. Always dilute your ACV in a large glass of water. It will help make it taste better. You could also try drinking your diluted solution through a straw or rinsing your mouth afterward to limit the exposure to your teeth. 
    2. Stick to the natural stuff. Some people take apple cider vinegar capsules, but these may contain added calories that would break your fast. 
    3. Try taking it at the start of or during your fast. Our users have said it can really help with managing appetite (which subsequently can help weight loss, among other things), even if the scientific research on that potential benefit is limited.
    4. Keep an eye out for tummy troubles. If you experience stomach discomfort, acid reflux, or sudden weight loss, stop taking ACV and speak with your healthcare provider.
    5. Stay hydrated. Drinking enough water is always important — especially when dehydration is one of the major intermittent fasting side effects — so don’t let your glass of ACV be your one-and-done as far as the water bit goes.

    Simple’s expert opinion and final thoughts

    At Simple, we believe intermittent fasting + apple cider vinegar could go hand in hand — drinking it in limited, diluted qualities every so often won’t pose any harm to the majority of people. 

    But as far as whether combining the two actually adds up to any health benefits? We don’t have enough research to support a strong recommendation. 

    As always, check in with your healthcare provider before making any significant changes to your eating routine, and be especially cautious about ACV if you’re on insulin or diuretics. 

    Then, if you need extra support in taking the next steps in your fast — whether or not apple cider vinegar is part of the plan — we’re here to be on your team. From getting started and staying motivated to troubleshooting intermittent fasting mistakes and circumventing “intermittent fasting not working” roadblocks, we’ve got everything you need to get to where you want to go. Just take our Simple quiz to let us show you what we’ve got. 

    Frequently asked questions about apple cider vinegar and intermittent fasting

    As long as you only have a tablespoon or two, apple cider vinegar doesn’t break ketosis — nor does apple cider vinegar stop autophagy. Anything fewer than 10 calories won’t break you out of a fasted state, and each tablespoon of ACV contains just three calories.

    Although there is some limited evidence to suggest ACV may support better blood sugar control and better glycemic responses, apple cider vinegar isn’t a carb blocker.[10] It doesn’t reduce or limit the amount of carbs your body digests.[11]

    There aren’t really any strict no-nos as far as what you shouldn’t do after drinking ACV, but it may be helpful to follow the usual recommendations for after eating, which include not going to bed or lying down right after. Wait 20–30 minutes for the acid to settle, and if you’re going to eat, avoid foods that stimulate acid, like sugar, processed foods, and sweetened sodas and juices. Don’t forget to drink lots of water without the ACV, too!
    ACV may have a pop culture rep for being a good detox supplement, but we don’t have substantive reason to believe apple cider vinegar can clean out your liver.

    There is some very limited evidence that ACV can affect hormones in specific circumstances,[12] but so far, we don’t have enough info to understand if, when, and how apple cider vinegar may impact hormonal balance. So, the answer for now is no.

    1. Launholt TL, Kristiansen CB, Hjorth P. Safety and side effects of apple vinegar intake and its effect on metabolic parameters and body weight: a systematic review. Eur J Nutr. 2020 Sep;59(6):2273–89.
    2. Petsiou EI, Mitrou PI, Raptis SA, Dimitriadis GD. Effect and mechanisms of action of vinegar on glucose metabolism, lipid profile, and body weight. Nutr Rev. 2014 Oct;72(10):651–61.
    3. Lim J, Henry CJ, Haldar S. Vinegar as a functional ingredient to improve postprandial glycemic control-human intervention findings and molecular mechanisms. Mol Nutr Food Res. 2016 Aug;60(8):1837–49.
    4. Hasan F, Hamilton K, Angadi S, Kranz S. The Effects of Vinegar/Acetic Acid Intake on Appetite Measures and Energy Consumption: A Systematic Literature Review. Current Developments in Nutrition. 2022 Jun;6(Suppl 1):285.
    5. Martini N. Potion or Poison? Apple cider vinegar. J Prim Health Care. 2021 Jun;13(2):191–2.
    6. Hadi A, Pourmasoumi M, Najafgholizadeh A, Clark CCT, Esmaillzadeh A. The effect of apple cider vinegar on lipid profiles and glycemic parameters: a systematic review and meta-analysis of randomized clinical trials. BMC Complement Med Ther. 2021 Jun 29;21(1):179.
    7. Adafer R, Messaadi W, Meddahi M, Patey A, Haderbache A, Bayen S, et al. Food Timing, Circadian Rhythm and Chrononutrition: A Systematic Review of Time-Restricted Eating’s Effects on Human Health. Nutrients [Internet]. 2020 Dec 8;12(12).
    8. Anderson S, Gonzalez LA, Jasbi P, Johnston CS. Evidence That Daily Vinegar Ingestion May Contribute to Erosive Tooth Wear in Adults. J Med Food. 2021 Aug;24(8):894–6.
    9. Darzi J, Frost GS, Montaser R, Yap J, Robertson MD. Influence of the tolerability of vinegar as an oral source of short-chain fatty acids on appetite control and food intake. Int J Obes . 2014 May;38(5):675–81.
    10. Cheng LJ, Jiang Y, Wu VX, Wang W. A systematic review and meta-analysis: Vinegar consumption on glycaemic control in adults with type 2 diabetes mellitus. J Adv Nurs. 2020 Feb;76(2):459–74.
    11. Salbe AD, Johnston CS, Buyukbese MA, Tsitouras PD, Harman SM. Vinegar lacks antiglycemic action on enteral carbohydrate absorption in human subjects. Nutr Res. 2009 Dec;29(12):846–9.
    12. Wu D, Kimura F, Takashima A, Shimizu Y, Takebayashi A, Kita N, et al. Intake of vinegar beverage is associated with restoration of ovulatory function in women with polycystic ovary syndrome. Tohoku J Exp Med. 2013 May;230(1):17–23.