The definition of a fast, according to the dictionary, is this: "to abstain from all or some kinds of food or drink, especially as a religious observance." Not very helpful, right? "all or some"? What foods and drinks can you eat and drink while you're fasting?
The answer is, unfortunately, not very easy. It all comes down to two things: what type of fast you're doing, and how strict you are about observing it. In other words, it's all about the limitations of the fast itself, where they come from, and how well you can stick to them.
If you're looking for foods that you can eat that won't break a fast, sadly, there actually aren't any. There are a few liquids that you can have that won't break a fast, though:
- Black coffee
- Plain tea
- Salt water
- Non-sweetened electrolyte water
- Non-sweetened sparkling water
- Lemon juice (1 tbsp or less)
- Apple cider vinegar
That's about it.
Of course, some fasts don't allow liquids of any kind as well. So, if you're interesting in learning more about fasts and when (and what) you can eat and drink, we'll learn about the different kinds of fasts you might be observing.
Starting from the most restrictive, you have:
The Full Fast
The full fast is by far the most restrictive and difficult kind of fast out there. This is the kind of fast you see promoted by strict religious people, as it was seen in the bible a few times.
The restrictions on a full fast are complete. You cannot eat anything, and you cannot drink anything, not even water. These fasts lasted about three days in the bible, though modern science indicates that three days is just about the limit for how long a human can live without water. There's no way you can perform a full fast for more than three days without suffering extreme consequences and potentially death.
As such, we absolutely do not recommend performing a full fast without a ton of preparation, medical supervision, and backup plans to abandon it as necessary. Total fasts like this are meant to be an extreme statement, and even in the best case scenario, they lead to extreme dehydration. This can cascade into all manner of issues throughout the body as it starts to consume itself to stay alive. Just don't try it without an extremely good reason.
A variation on this kind of fast, called a medical fast, is typically a precursor to any surgery or medical procedure that involves the digestive system, the bloodstream, or anesthesia. Typically, doctors will ask you to fast for the night before your procedure. This allows things like oral contrast to work its way through your digestive system fast enough for imaging, and it helps prevent vomiting while under anesthesia, which can lead to aspiration, infection, and in extreme cases even death. Unlike a more religious-based fast, though, a medical fast is typically never longer than 6-12 hours.
The Water Fast
The water fast I similar to the full fast, in that you cannot eat or drink anything. The exception is right there in the name: water. You can drink water, both to keep yourself hydrated (and alive), and you avoid everything else.
These are traditionally short fasts because, again, it can be dangerous to avoid eating or drinking much of anything for a long period of time. This kind of fast can keep you alive longer than a full fast, since your body needs water more than just about anything, but it's still not going to be comfortable.
These kinds of fasts are typically performed in short bursts of 1-2 days as part of an overall intermittent fasting plan, which we'll talk about later. They're also not recommended outside of that context.
The Liquids Fast
This kind of fast is similar to the water fast, except it can be expanded to other kinds of liquids. For example, you might cut out solid foods, but drink juice and coffee to get your nutrients and your energy. Others might use something more like broth to get their nutrients. This is what the "breatharian" practice largely does, though it's not so much a fast.
Liquid fasts can wreak havoc on your digestive system, which will have nothing solid to process. This means bathroom breaks are a lot more frequent, food passes through you very quickly, and you'll feel hungry pretty quickly after you "eat" your beverage-based nutrition. As such, some extended liquid fasts use protein powder and fiber supplements to try to suppress appetite and make it easier to resist the urge to break the fast in other ways.
The Religious Fasts
Plenty of different religious traditions around the world use fasting in various ways and in various forms. The bible, as mentioned, has a few examples of individual pursuing a total fast for a few days to make a point of faith. More commonly, though, you have religious fasting events, such as the Christian Lent, the Islamic Ramadan, the Jewish Yom Kippur.
Different kinds of religious fasts have different rules. For example, Lent is a fast that the individual can pick what they want to give up. Many people choose a treat like chocolate or sugar more generally. Some pick a particular kind of protein or meal they would otherwise enjoy normally. Many also pick non-food items and the fasting doesn't interrupt their diet at all, like a TV or Internet fast. Obviously, if you're giving up the Internet for Lent, you can eat whatever you want.
Yom Kippur is a single day of fasting lasting 25 hours and is a total fast, refraining from food and drink including water. It can be very harsh on the system, of course, but for a single day it's rarely truly dangerous for those who don't have other health issues that could exacerbate it. The Jewish faith has several other religious fasts as well, peppered throughout the year.
Ramadan, meanwhile, is an interesting religious fast that is in some ways similar to intermittent fasting. For the month-long observation of Ramadan, participants are not allowed to eat or drink – or engage in sensual activity – between dawn and sunset. It's a total fast for half of the day, but allows for whatever food and drink the individual wants after sunset.
Religious fasts all vary as much as the individual participating, the tradition they follow, and the personal level of observance they practice. Religious fasts also tend to make allowances for those with health issues or situations that otherwise mean they wouldn't be able to fast without complications; after all, it's about faith and observance, not about suffering.
The Intermittent Fast
Intermittent fasting is fasting that, similar to Ramadan, takes place for part of the day. The idea is to restrict when you can eat rather than what you can eat, so you're less likely to sneak in hundreds of calories in snacks. Cutting out some eating through fasting can help the faster lose weight, but many people tend to pick a type of fast that doesn't quite challenge them, leading to less than stellar results.
There are a bunch of different kinds of intermittent fast, with different restrictions on them. All of them are more based on time than on particular foods, though.
- The 12/12 fast. This is a fast for 12 hours of the day, and allows you to eat freely during the other 12. For example, you might eat breakfast at 6am, and dinner at 5pm, and fast from 6pm to 6am the next day.
- The 16/87 fast. This is slightly more restrictive than the 12/12 fast, where you fast for 16 hours per day and allow yourself to eat only in the remaining 8 hours. For example, skipping breakfast means you eat your first meal of the day around 11am, eat dinner five or six hours later, and then eat nothing from 7pm to 11am the next day.
- The 5/2 fast. This is a fast that stretches the time scale to days rather than hours. Instead of dividing up the days, you divide up the weeks. This is a "five days on, two days off" fast, where you pick two non-sequential days of the week to fast for the full day. Sometimes this fast is a total fast, but more often it's just an intense caloric restriction, limiting you to around 500 calories for the fasting days.
- The alternate day fast. This is a type of fast where you alternate days, one day on, one day off. Again, this tends to use a caloric restriction rather than a total fast, but which you choose depends on your own desires. This is usually an ongoing day on, day off pattern with no accounting for the odd number of days per week, thus making it a two-week cycle.
- The weekly fast. This is similar to the 5/2 fast except instead of picking two days off, you only pick one. You can also call it the 6/1 fast. Picking a single day to total or near-total fast can help cut calories, but you need to avoid making up for it the next day.
- The Meal Skip. This isn't a "fast" so much as just a way to cut calories. The idea is to just pick one meal a day to skip, which can vary depending on the day. Feel hungry in the morning? Eat breakfast and skip lunch. Feel like you don't need the pick-me-up? Skip breakfast and only eat lunch and dinner.
- The Warrior Fast. This is an extreme fasting plan where you limit yourself to only small portions of low-calorie foods like fruit during 20 hours of the day, and in the remaining 4 hours, you eat a single large meal. This helps limit how much you eat because that one meal won't pack in three meals worth of food, due to satiation limits, but still gives you enough energy to keep going.
Intermittent fasting rarely puts specific dietary restrictions on the participant, because it's usually a diet plan picked up by people who have been otherwise unable to follow diets. The idea being to change the times you eat rather than the foods you eat, so you can still enjoy what you want out of your food while maintaining a caloric deficit.
The trouble many people run into is that they fast for part of the day, and then they simply eat more during their eating periods. An intermittent fast is only going to work for weight loss if you maintain that caloric deficit, so if you just eat 2x2,250 calorie meals a day instead of 3x1,500 calorie meals a day, you're not actually doing anything beneficial.
Many intermittent fasts can work well when paired with a Lent-style ingredient fast as well. If you decide to limit when you eat, and also limit how much of a certain ingredient, like sugar, that you eat, you can combine the effectiveness of both kinds of fast.
That said, however, the intermittent fasting plan doesn't actually restrict what you can eat; it's all down to your other kinds of restrictions.
So, what can you eat without breaking your fast? It's a hard question, because the answer could be anything or it could be nothing. You have to recognize the reason you're fasting, and analyze whether or not the food you want to eat is going to work against your goals. In other words, it's entirely up to you.
The one similarity between each of these types of fasting is that, while fasting, you aren't supposed to have any food at all, and depending on the type of fasting, no liquid either.
Intermittent fasting is increasing in popularity, so if you're here for that, you are limited to the liquids that we mentioned at the beginning of this article.
Have you tried fasting before, for a religious observance, for a weight loss goal, or for any other reason? If so, please, tell us about it in the comments. What were your experiences with the fast? How did it make you feel, and what did it accomplish for you?