Intermittent Fasting? Find Out What Really Breaks Your Fast

Diets can get a bit tiresome. All that telling you what you can and can’t eat, right? So maybe you’ve changed tactics, and have settled on an “eating protocol” instead of a diet, which probably means that you’re doing intermittent fasting, or IF. So if you’re on the IF train, you know that this type of eating protocol doesn’t necessarily dictate what you eat (like keto or paleo, for example), although it’s suggested that you should still eat a healthy diet to get the most benefits, it’s instead all about when you eat. Ok, sounds simple enough, but you might still have questions about what you can put in your mouth (if anything at all) during your fasting time, so read on for a handy guide to what breaks your fast. 

Intermittent Fasting Options

While studies are still being done on intermittent fasting, it’s become popular as a weight loss tool, as well as one for boosting health, since the studies we do have suggest that IF promotes ketosis (and thereby increases fat burn), boosts cognitive functioning, reduces inflammation, and might even boost longevity. 

And it’s definitely not one size fits all, which is another reason it’s become so popular. You have different options for how to set up your IF schedule, depending on what works for your body and lifestyle. 

For example, you can try:


  • Time-restricted eating – This eating pattern involves fasting every day for 12 hours or longer and eating in the remaining hours. A popular example is the 16/8 method, which means that you have a daily 16-hour fast and an 8-hour eating window, during which you can fit in 2, 3, or more meals.
  • The 5:2 diet – The 5:2 diet involves eating as you normally do 5 days of the week, and restricting your calorie intake to 500–600 on the remaining 2 days.
  • Eat Stop Eat – Eat Stop Eat involves a 24-hour fast once or twice per week.
  • Alternate-day fasting – With alternate-day fasting, the goal is to fast every other day.
  • Meal skipping – This type of IF is generally good for beginners, since it involves choosing one meal a day to skip.
  • The Warrior Diet – On the other hand, this type of IF is a little more extreme, and probably better for people who have tried other types of IF already. It involves eating minimal amounts of raw fruit and veggies during the day and eating one large meal at night. 

What Breaks a Fast? 

So if one of these types of eating has become your cup of tea, what should your fast look like? Can you, for example, have an actual cup of tea during your fasting window? Let’s look at what actually breaks a fast according to experts, what kind of flexibility you might be able to add to your fasting routine, and what you should definitely avoid.

Can you have any calories during a fast?

First of all, when we say “fast,” how strict are we talking? Can you have more than just water, one of the only true calorie-free things that we consume? Experts are actually a bit split on this question, and tend to talk about this debate in terms of two of the known and sought-after benefits of IF: ketosis and autophagy:

  • Ketosis is a process that happens when your body doesn’t have enough carbohydrates to burn for energy, so it burns fat and makes things called ketones, which it can use for fuel. In other words, putting your body into ketosis (which is also the goal of the “keto” diet), increases fat burn.
  • Autophagy is the body’s way of cleaning out damaged cells, in order to regenerate newer, healthier cells. This process is less on the weight loss side of IF, and more on the health boosting side (although losing weight will boost your health, as well!)

Talking about these processes, which are the goals of IF, is where things get a little unclear when it comes to how many – if any – calories you should be consuming during a fast. Some experts, like Benjamin Horne, Ph.D., a genetic epidemiologist who has published research on the effects of intermittent fasting, say that while “technically, consuming any calories breaks a fast,” ketosis might actually remain active with the consumption of certain macronutrients (or carbs, fat, and protein). According to Horne, “One mechanism that is known to remain active when a small amount of food is consumed is ketosis—as long as you consume less than 50 grams of carbohydrates [in a day].”

Autophagy, on the other hand, seems a little trickier. According to Horne, “In humans, it appears that autophagy does not remain as active when any food is consumed.” He thinks that even the 2-5 calories in a cup of black coffee could throw the process out of whack; other experts aren’t so sure, though.  

Says Vincent Pedre, M.D., an integrative physician and gut health expert, “I’ve heard good debates about whether coffee can break a fast. We don’t have any good evidence to show either way. I would say if you’re drinking organic black coffee—no cream, no sweeteners—then you should be fine. That said, I would say stick to as close to zero calories as you can during your fasting hours with plenty of clean filtered water; herbal teas are also good.”

Is “dirty fasting” the key to consistency?

water with lime in it
Clean fasting is when you eat minimal calories during your fast.

Unfortunately, we can’t give you any definitive answer about having any calories at all during your fast, but it seems as though getting close to zero calories should be your goal if you want to get the full benefits of your fast. You probably know that already, though, and maybe it’s been holding you back from going no holds barred on intermittent fasting – which in turn is keeping you from getting any benefits at all! 

So, with that being said, some experts actually recommend consuming small amounts of calories from certain foods, if the choice is an all-or-nothing one between water-only fasting and not staying consistent with your IF at all. So, if you’re not sure that “clean fasting” is something you can stick with, you could consider what’s known as “dirty fasting.” Check out the difference:

  • Clean fasting means that you are consuming the minimal number of calories that you can during your fast, by generally sticking to water or other noncaloric beverages. 
  • Dirty fasting is a form of modified fasting that allows the addition of a certain number of calories during the fast. Experts don’t fully agree on what is the best way to do a dirty fast, but many say that you should stick to foods under 100 calories that are high-fat and won’t spike blood sugar. For example, integrative physician Amy Shah says of her own dirty fasting method, “For me, I like to fast as long as possible with just water—that might be 13 or 14 hours of a water fast—then I’ll have my tea with almond milk (the start of my ‘dirty fast’) and end at around 16 hours.”

Dirty fasting is definitely an option if it’ll keep you happy and consistent, just keep in mind that fewer studies have been done on this type of fasting. According to Samantha Cassetty, M.S., RD, nutrition and wellness expert, “keep in mind that there are almost no studies on this form of fasting, and without evidence, we can’t say whether this modified fasting protocol would produce similar benefits as might be experienced through other intermittent fasting protocols.”

If you’re going to consume calories, where should they come from?

If you’ve decided that you are going to consume some calories during your fast to help keep you on the intermittent fasting train, it’s not only important to remember that there are fewer studies on the effects of that type of fasting, but also that you shouldn’t just be grabbing whatever’s in reach. When we say “dirty fast,” we don’t mean it’s time to bust out the Oreos! 

There are some things that have calories (and therefore technically break your fast) that might still allow you to get some of the benefits of IF. For example:

  • Tea and coffee – Yes, these innocuous, water-based hot drinks technically have a few calories! That means they might (MIGHT) throw you out of autophagy, but that’s not even all that clear. In fact, in studies with mice, it looked like coffee actually induced autophagy, so we’re going to give that one a big shrug. And, since these drinks don’t seem to interfere with ketosis, and in some cases, coffee can even have an appetite-suppressing effect, we’re going to give the thumbs up to some black coffee or a comforting cup of tea.
  • Certain fats – Just like you can choose to do a dirty fast, you can also choose to do a “fat fast,” or one that includes hot drinks blended with fats like coconut oil, ghee, or grass-fed butter. This type of fasting is recommended less for weight loss. According to integrative dietician Ali Miller, R.D., “Low body fat levels can drive imbalances in hormones, so a ‘fat fast’ would be appropriate for people looking for moderate body composition changes or maintenance,” But it certainly won’t be bad for your waistline: this type of fasting allows you to push off hunger and cravings (so you don’t eat a full-blown meal) and allows for ketosis, so it is still good for maintaining a healthy weight. Plus a little fat (especially in the morning) helps keep you regular! You might not get the full benefits of autophagy, though, since you will be breaking your fast.person holding a mug full of broth
  • Bone broth – Again, bone broth does have calories, so it will technically break your fast, but even renowned IF expert Jason Fung, M.D. says a bit of bone broth is a great way to keep you on track, while giving you the electrolytes and minerals that your body might need during a longer fast. Consuming water alone, especially if your fast is longer than 16 hours, can reduce electrolyte levels in the body, leading to potential complications such as low blood pressure, confusion, nausea, muscle spasms, and fatigue. Just be careful with too much bone broth, as it seems to interfere with autophagy (as a lot of protein does). 

Is there anything you definitely shouldn’t have? 

A lot of things are off the table during your fasting window, but there is one little thing that you might not even be worrying about, which experts say to avoid on IF: artificial sweeteners. Yes, they technically have zero calories, but experts pretty much agree that just because something doesn’t have any calories, doesn’t mean it doesn’t affect your body. 

According to Miller, “Just because something is noncaloric doesn’t mean it is free of metabolic influence. The taste of sweet impacts GLP-1 receptors on the tongue, which enhances insulin release—this is not ideal, as insulin has a negative impact on fasting and may drive blood sugar drops.” And blood sugar spikes are exactly what you’re trying to avoid while fasting!

If you’re doing intermittent fasting, hopefully it’s feeling like the right alternative to traditional diets to you, and you’re feeling good! But if you’re also feeling confused about the “right” way to do it, know that there is some flexibility – and also remember that the way you choose to eat should make you feel good. If you feel like you can’t do the whole full-blown water fast thing, you can try one of the above alternatives if it’ll keep you happy and consistent. But you can also try tweaking what you’re doing during your feeding window: make sure you’re eating enough and eating the right foods. Bottom line: do what works for you! And make sure you tell us how your IF journey is going!

Co-written by Joanna Bowling

Intermittent Fasting 101

Intermittent fasting has become a popular trend over the past couple of years. Why? Well it has so many benefits, such as helping shed extra pounds, improving health, and helping you live longer! Contrary to popular belief, your body does not go into “starvation mode” or store fat when you go without eating for hours. A lot of studies show that intermittent fasting has many benefits for your body. So how do you go about starting and easing into intermittent fasting?

Types of Intermittent Fasting

different colored clocks of all sizes layered on top of each other
There are different kinds of intermittent fasting, and you can choose the time you want to start fasting and end it.

There are several ways of doing intermittent fasting. Some do it daily, while some people do it weekly. Here are the most popular forms of intermittent fasting:

  • 16/8– This is also called the Leangains protocol. For this kind of fast, you fast for 16 hours, and then consume all of your calories during the 8 hour window that you are not fasting. For example, you can begin fasting from 8pm until 12pm the next day (16 hours), and then can eat from 12pm-8pm. You can choose which hours work best for your schedule.
  • 20/4– The same concept applies as the 16/8 method, except you fast for 20 hours and eat during a 4 hour window.
  • East Stop Eat– This form of intermittent fasting requires more discipline. You fast for 24 hours for one or two non-consecutive days per week. The easiest way to do this kind of fasting is to fast from one day’s dinner to the next. You can do this from lunch to lunch, or breakfast to breakfast.
  • The 5:2 Diet– This diet focuses on the amount of calories you consume for the day. You limit caloric intake to 500-600 on two non-consecutive days of the week. Generally for this diet women should consume 500 calories, and men consume 600 calories. During the other 5 days you would eat normally.
  • Alternate Fasting– This is also called the ADF protocol. This is when you alternate between days of eating normally and days of fasting. You fast every other day, which may be harder for some to do. Studies have shown people are more likely to abandon their diet.

Can You Eat At All During Fasting?black coffee in a white mug on top of coffee beans

tea cup with tea in it and a daisy

Generally no. When you are fasting, all you can have is water, black coffee, tea, and other non-caloric beverages. The goal is not to consume any calories during the fast. When you fast, your body adjusts hormone levels to make stored body fat more accessible. 

Health Benefits

Reduced Insulin Resistance– During the fasting period, lower insulin levels improve fat burning in the body. Not only will it improve fat burning, but the lowered insulin levels will help encourage muscle growth. Studies show that fasting reduces insulin by 20-31%.

Detox The Body– When you fast, your body removes toxins. One way this occurs is from shedding weight. When you intermittently fast, your body will burn fat, using it for the energy it’s not getting from food. The fat cells are the usual culprits for toxin storage, keeping it from what we eat and breathe.

When you cleanse your body from toxins, you will find that you have more energy, stamina, clear skin, better brain function, and restful sleep patterns. 

Lose Weight– Because your body lowers it’s insulin levels, your body burns\ the fat for fuel, and it no longer receives the signal to store extra calories as fat. Intermittent fasting can increase norepinephrine, a hormone and neurotransmitter that can boost your metabolism! That way, your body will burn calories throughout the day.

caucasian belly with hands over the button in a heart shape, and a daisy over the belly button
Fasting boosts gut health and mood.


Improved Gut Health & Mood– Not only does your body burn more, but your gut health improves. Your mood and mental health go hand in hand with your gut microbiome. So, when your gut reboots due to intermittent fasting, your stomach and your mood are overall happier.

Heart Function– At least one study indicates that people who follow a fasting diet may have better heart health than people who don’t. When you fast, your levels of hemoglobin, red blood cell count are affected, in a good way. This improves heart health. 

Autophagy- The process of cells eating themselves to get rid of damaged cells, and recycle into better, more youthful ones is called autophagy. Viruses, bacteria, and other pathogens are destroyed in this process. The simple way to activate this is by fasting. Damaged cells are removed, and cellular and tissue rejuvenation occur.

Brain Function– Your body will burn glucose reserved in your blood and liver when you are fasting. The liver will turn the fat into ketones and use them for fuel. Your brain prefers ketones over glucose, and in turn, will work better and increase your ability to learn and think.

How It Affects Your Cells

Some of the changes your body will go through are:

  • Cellular Repair– Also known as autophagy, your cells break down and recycle old proteins that accumulate within cells, and make new healthy cells. Viruses, bacteria, and other pathogens are destroyed in this process. Damaged cells are removed, and cellular and tissue rejuvenation occur.
  • Growth Hormone– The levels of growth hormone increases by 5 times or more. This growth hormone aids in fat loss, and muscle gain.
  • Metabolic Rate– Your metabolic rate boosts as much as 3-14%when you are fasting for two days. However, other studies suggest that if you fast for longer than 48 hours, then you will slow down your metabolism.
  • Insulin– When fasting, your insulin levels stay low. Low insulin levels means that fat burning is increased. 

Easing Into Intermittent Fasting

It can be easy to begin fasting, but most people will give up within the first week, because they are not prepared. Some tips to make the transition easier:


  1. Start Slow– The easiest way to start fasting is by skipping a meal. Skip a meal, breakfast for example, and have water or coffee instead. You can eat lunch, which will break the fast.

    water bottle pouring water into a cup
    Drink a lot of water and electrolytes.
  2. Stay Hydrated– Drink a lot of water and electrolytes. This is very important for cognitive function. A plus is that water can help you feel full when you are hungry.
  3. Eat High-Quality Foods– When it comes time to break your fast, make sure to eat foods that are beneficial and essential to your health. Try to avoid junk food. Eat foods full of vitamins, minerals, and protein so you can fuel your body correctly. 
  4. Plan & Prepare– When you know when you are going to eat, it will make you obsess over the thought of food less. There are apps you can download that help you keep track of your fasting hours and send you notifications of when to start fasting, and when you have completed fasting and can eat. The app will have a timer to show how long you have been fasting, and how much longer you have 
  5. caucasian woman sleeping in a bed with white sheets and pillowcase
    Sleep is very important for cognitive productivity, fat loss, and metabolic reasons.

    to go.

  6. Sleep!– Get an adequate amount of sleep! Sleep is very important for cognitive productivity, fat loss, and metabolic reasons. When you do not sleep enough your hormones are affected as well as your insulin sensitivity. The less sleep you get, the hungrier you are. 

Consult With Your Doctor About Fasting If You:

  • Are underweight or have a history of eating disorders
  • Are pregnant or trying to conceive
  • Have a medical condition
  • Have diabetes
  • Have low blood pressure
  • Take medications