Dry fasting – the complete guide

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When you hear the words “dry fasting”, what do you think of? 

Do you wonder if this is a fasting protocol where alcohol is prohibited for 16 hours, and then it’s whiskey, gin, and vodka for the next 8?

Maybe an image of you on a sandy desert, sweating while you fast under the beating sun, pops into your head.

Or you contemplate the kinds of foods you might be “allowed” to eat on a dry fast: cornflakes without milk, crackers, stale bread, sauceless chicken. 

A dry fast is none of these things. 

Dry fasting means you restrict food AND liquid during your fasting periods. Yep, that’s right—no water, no tea, no black coffee, and no food. 

We’d never recommend dry fasting to you (or an alcohol fast, a desert fast, or a cracker fast) as a way to improve your health.

But we do want to help you learn more about it, so you have all the information about what it is, why other people might recommend it, and can make a decision about whether you want to try it or not.

Key takeaways fasting

  • Dry fasting is a fast that restricts everything including water. 
  • “Is dry fasting safe?” remains a question to be answered. It can lead to dehydration and nutrient deficiencies.
  • You can lose weight with dry fasting but likely won’t sustain that weight loss once you return to your previous lifestyle.
  • It’s not clear whether the benefits of dry fasting come from removing water, or simply fasting.

What is dry fasting?

Like ironing, fasting also comes in extreme forms. Dry fasting is one of those extremes because, when you do it, you fast from everything.

Any of the intermittent fasting methods can be done dry. (Except water fasting, obviously.) 

Whether you follow a 16/8 protocol, the 5:2 diet, or alternate day fasting, if you remove all liquid intake from your fasting periods, you’re dry fasting.

During your eating window, you can eat and drink as you wish.  

It’s pretty straightforward. 

But whether it’s safe or effective is questionable. We’ll look at dry fasting’s benefits, risks, and results later. 

How does dry fasting work?

Unlike other fasting protocols, dry fasting means that in addition to food, no liquid (even H2O) is allowed during your fasting window.

There are no set dry fasting rules, stages, or guidelines. 

Here’s the essence: 

  • restrict liquids and food during your fasting window
  • eat and drink as you typically would during your eating window

It’s no more complex than that.   

One popular argument for how dry fasting works is that, when you go without food or water for a period of time, your body increases fat metabolism to access the water in your fat cells, and you lose weight. 

But, there’s a lot more evidence that drinking water assists weight loss. For instance: 

A systematic review, which showed that increasing total water intake and drinking water before meals can support weight loss [1], and another systematic review which showed that increased water consumption while following a weight-loss program reduced body weight after 3-12 months—compared to following the weight-loss program alone.[2]

This is one reason why a plentiful water intake helps you succeed at reaching your weight loss goals through intermittent fasting (and why not drinking enough is one of our top intermittent fasting mistakes).

The best way to prepare for dry fasting

To prepare yourself for dry fasting, there are a few steps you can take. 

  1. Talk to your healthcare provider. 

Before you start, talk to your healthcare team about dry fasting. They will have some insights on how this might interact with your health, and can guide you on whether it’s safe for you to try it. 

  1. Get comfy with intermittent fasting. 

Start by following a regular intermittent fasting protocol for a few days or weeks. Practice drinking enough and eating plenty of fruit and veg during your eating window, to help you get used to:

  • eating fewer calories
  • the act of fasting itself
  • getting enough hydration in a shorter period of time

If this is where you’re at, we can help. Head to our SIMPLE quiz to get started with an easy intermittent fasting protocol—we’ll recommend the one that’ll work best for you. 

  1. Make sure you are hydrated in the days leading up to starting your dry fasting protocol. 

Before you start dry fasting, focus on being fully hydrated, by:

  • drinking plenty of water 
  • cutting out caffeine and alcohol

This will make sure you’re in a good place to kick off. 

How long can and should you dry fast?

Studies on dry fasting tend to focus on Ramadan, where the fast periods—i.e., the unbroken length of time someone goes without food or water—can be between 10-19 hours, and intermittent dry fasting is done for 30 days. 

We don’t have any real evidence that it is safe to dry fast for longer than this if you’re doing it at home, without the care and supervision of a medical professional. 

The best way to break your dry fast

To break your dry fast, start with a big ol’ glass of water and follow that up with something your stomach can easily digest, like a green smoothie, to give your body energy.

When you come to break your fast, start out with a glass of room-temperature water, then eat something that’s easily digestible and nourishing. Try eating light foods that release energy steadily, like:

  • a veggie bean salad
  • chicken broth 
  • a smoothie with berries and live yogurt 

Important note: If at any point during your fast you feel:

  • dizzy
  • light-headed
  • spaced out
  • exhausted
  • sick 

… break your fast. 

These are your body’s ways of telling you to eat and drink. Stay checked in, pay attention to how you feel, and follow your body’s signals.

Dry fasting and weight loss

Intermittent fasting is a reliable method of weight loss, but whether dry fasting brings any benefits to the party, over and above those of regular intermittent fasting, is unclear.

A 2013 study found that 240 healthy adults, who intermittently dry fasted for at least 20 days during the month of Ramadan, decreased their body weight and BMI.[3]

A scientific review suggests dry fasting during Ramadan has similar benefits on weight loss as time-restricted fasting (like 16/8).[4]

But dry fasting during Ramadan is short term (it takes place over 30 consecutive days) and its results are too, meaning the weight loss you achieve likely won’t be sustained once you stop dry fasting. 

Currently, there isn’t enough evidence to demonstrate how effective dry fasting is for weight loss over the long term. 

Health benefits of dry fasting

Is dry fasting good for you? That’s a good question!

There are some potential benefits of dry fasting. 

However, bear in mind that these benefits are also found in studies of other intermittent fasting methods, and there are no studies that compare regular intermittent fasting methods with dry fasting. 

Just as with weight loss, we can’t know whether dry fasting offers any benefits beyond those of intermittent fasting in general.  

Fat loss

In a 2016 study, those who dry fasted during Ramadan lost weight, and lost body fat, while keeping their muscle mass.[5]

Better blood sugar

A meta-analysis found blood glucose was decreased after dry fasting [6], and another review found similar effects, as well as increased insulin sensitivity.[7]

Decreased inflammation

Dry fasting could help reduce the concentration of inflammatory markers TNF-a, CRP, and IL-6.[8,9]

That said, a systematic review found that the effects of dry fasting on the immune system were small, and temporary.[10]

Lower cholesterol levels

A study found that dry fasting could improve both LDL and HDL levels.[6]

Improved bone health

Dry fasting could have a positive impact on bone health, according to the 2015 study.[11]

Health risks of dry fasting

And, of course, there are risks. 

Nutrient deficiencies

One of the tricky things with dry fasting is making sure you get enough water in during your eating window. 

How easy or tough this is depends on the method of intermittent dry fasting you choose. 

If you did 16/8, for instance, you could drink enough water during your 8-hour eating window. 

But, if you went for a more restrictive fasting plan like the warrior diet, trying to drink enough water in such a short period would take up so much room in your stomach, you wouldn’t be able to eat enough whole, nourishing foods, and that would leave you short on nutrients and energy. 


If you don’t drink enough to replace the water you lose, you become dehydrated. That’s a serious issue that can cause: 

  • a buildup of waste in your kidneys (as you’re not excreting it out through the urine) 
  • an increased risk of kidney stones and urinary tract infections [12,13]
  • slower, more muddled thinking
  • low mood 
  • headaches 
  • dizziness 
  • orthostatic hypotension (when your blood pressure drops when you change position and makes you feel faint or unsteady)

In a 2019 study, not drinking water for 36 hours caused fatigue, short-term memory loss, reduced attention, and reduced reaction time.[14]

To make sure you’re hitting your hydration goals (and, more importantly, avoiding those dehydration risks), take our SIMPLE quiz and get your hands on our hydration tracker (as well as a fasting buddy). We’ll send you reminders to drink, so the only thing you’ll have to worry about is whether you’re adding some lemon or mint to that next glass of water.


All fasting involves hunger, yet dry fasting makes that hunger harder to handle. 

There are many ways to hack hunger while fasting. One of the best:

Drink water. 

Without that option, hunger will persist longer and feel more intense. 

It’s not just dehydration that leads to fatigue, crankiness, difficulty focusing, and headaches. Hunger can cause all those things too. 

Is dry fasting safe?

At SIMPLE, we don’t consider dry fasting to be safe. We wouldn’t recommend it as a health-improvement practice. 

And, there are some groups in particular who should stay away from fasting altogether. If you fall into any of these groups, only fast if you have the support and permission of your doctor:

  • you’re underweight according to your BMI (body mass index)
  • you have anemia
  • you have (or are at risk of having) an eating disorder, or a history of one
  • you have a health condition like diabetes or hypothyroid / hyperthyroid
  • you’re on medications (especially those which affect blood glucose or blood pressure)
  • you’re pregnant, breastfeeding, or trying to conceive
  • you’re very active 
  • you’re below 18 years old, or over 65

If you have to avoid fasting or you’re concerned about the safety of dry fasting, don’t worry. There are plenty of safe ways to lose weight and improve your health. Have a chat with your doctor about what might be right for you. 

Pros and cons of dry fasting

Straightforward to do Insufficient research to determine safety / efficacy
Weight loss can occur Weight loss may be short-lived
May have health benefits There are several risks to health
Unpleasant side effects


Dry fasting isn’t complex to do: Remove any liquid intake from your fasting periods and you’re there. It might help you to lose weight and enjoy better health. 


Or it may not. There’s not enough evidence to really know whether dry fasting is safe or effective. Any results you see are likely to be short term, and dry fasting can actually damage your health, as well as lead to side effects like fatigue and dizziness. 

Is dry fasting right for you?

If the thought of going without any food or liquid for an extended period sounds a bit extreme, then dry fasting probably isn’t for you. That’s ok, though, since there are other fasting protocols out there that might be a better fit.

You’re the boss of you, and your actions are always your choice. Ultimately, it’s your decision whether to try dry fasting or not. 

Before you decide, check in with yourself:

  • Are you fully aware of the risks?
  • Are you comfortable with those risks?
  • Do you know the signs that mean it’s necessary to break your fast and drink / eat something? 
  • Are you confident that intermittent dry fasting would suit you better than regular intermittent fasting? 

If you’re a yes to all these, take care and stay tuned in to your body as you fast.

If you’re a no to any of the above points but intermittent fasting sounds good to you, why not try the regular kind—i.e., when you fast, you don’t eat but you do drink calorie-free drinks—in any of the styles below:

  • Time-restricted feeding (TRF)

The most popular options here are:

For each of these, the first number is the amount of hours you’ll fast each day. The second number is the amount of hours you get to eat. With 16/8 intermittent fasting, for example, you’d fast for 16 hours and eat within 8 hours. 

These are SIMPLE, accessible options. Great for beginners, especially if you start with 12/12 and work your way up to longer fasts if you feel good. 

This is particularly relevant if your body is estrogen and progesterone dominant, as you might find that intermittent fasting interacts in a funky way with those hormones. Starting with a shorter fast helps your body adjust better. 

  • The warrior diet 

The warrior diet is also a time-restricted feeding option, where you fast for 20 hours and eat within 4. The hunger can be quite intense, though, and it’s not super easy to get all the food you need into that 4-hour time slot. 

If you like the sound of this one, again, start with a shorter fast and extend over time. 

  • Alternate day fasting (ADF) 

Just like it sounds, with alternate day fasting you eat one day, fast the next. On your fasting days, you’d eat 500/600 calories so it’s not a total fast, and that can make the hunger more manageable.

That said, fasting every other day is quite a tall order, so if you like the idea of this one, start with 5:2. (Keep reading; we’ll tell you about that next.)

  • The 5:2 diet

On the 5:2 diet, you’ll follow a modified fast of eating only 500/600 calories for 2 days. On the remaining 5 days of the week, you eat as you usually would. Another good option if you’re just starting out. 

  • Water fasting

Water fasting is a short fast—1-3 days tops—where you drink only water and eat no food.

We’ll be honest: if it’s a toss up between dry fasting vs water fasting, we’d choose… neither. 

For fat loss and health benefits, whether you’re male, female, or somewhere else on the sex and gender spectrum, regular intermittent fasting beats both dry and water fasting at delivering better, more long-lasting results, and is a safer option that’s kinder to your body and mind. 

Simple’s expert opinion and final thoughts 

At SIMPLE, we don’t rate dry fasting as a health-improvement method, and we’d recommend you don’t try it. (You’re probably very aware of this by now!)

Bodies fundamentally need water. We can’t survive long without it. 

And, if you’ve read any of our other fasting articles, you’ll know that we encourage a plentiful water intake during your fasts to help curb hunger, and to keep you hydrated.

If you’re feeling a bit bamboozled by choosing an intermittent fasting method, no worries. Try our SIMPLE quiz and we’ll help you get started

If you do try dry fasting, here’s what we’d say.

  1. Take very good care to hydrate when you’re not fasting. 
  2. Have a health professional support you through the process. 
  3. Bear in mind that the benefits you experience from dry fasting will depend on lots of factors, like:
    • your overall health,
    • how active you are, 
    • your age
    • how often you do it
  4. Listen to your body. It has wisdom that will guide you well, if you pay attention. 

Frequently asked questions about dry fasting

What happens if you dry fast for a week?

If you dry fast—i.e., went without water and food—for a week, you’d be putting your body into a very dangerous position. Our bodies are around 60% water. We need water to do bodily tasks, like flush out toxins and move nutrients around. Our energy, mental clarity, digestion, mood, etc., all need water to function at their best. 

Can I brush my teeth while dry fasting?

A “soft” dry fast (which is the kind we’re talking about in this article) can include brushing your teeth, taking a shower, and washing your face. A “hard” dry fast means zero contact with water. 

You can brush your teeth while dry fasting if you are “soft” dry fasting. 

What does dry fasting do to the brain?

It’s a good question: What does dry fasting do to the brain? Some think it delays aging and stimulates cell regeneration. However, the science doesn’t really support this. On the other hand, we do know for sure that dehydration—which is a real risk of dry fasting—impairs your cognitive abilities.  

Can you exercise while dry fasting?

You can exercise while dry fasting, but be careful. Without the ability to drink during your exercise session, you’re at greater risk of dehydration. If you want to exercise, do it during your eating window, and make sure to increase your fluid intake to cover the water you lose through sweat and breathing hard. 

Can I drink water during dry fasting?

You can only drink water during dry fasting when you are not fasting. You can drink during your eating window but otherwise, fluids of any kind are off the table.

Can you drink coffee on a dry fast? 

Again, you can only drink coffee during dry fasting when you are not fasting. You can drink during your eating window but otherwise, no fluids of any kind.

Does dry fasting burn fat?

Dry fasting can burn fat, according to some studies. Whether this effect is due simply to fasting or specifically to dry fasting, though, is unclear.

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