Does apple cider vinegar break a fast? Explained by Simple

Written by Aly Owen

Medically reviewed by Louise Bula, RD

Published on January 9, 2024 | Updated on June 14, 2024

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. 

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!

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

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

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.

Written by Aly Owen

Medically reviewed by Louise Bula, RD

Published on | Updated on June 14, 2024