- People use water fasting to lose weight quickly, “detox” their bodies, slow aging, and get healthier.
- Water fasting will help you lose weight and fat quickly, but most of the weight loss will be from water and you’ll lose muscle in the process.
- Water fasting doesn’t “detox” your body, slow aging, or offer any health benefits that you can’t get from safer, more enjoyable forms of weight loss.
Fasting is becoming more and more popular.
You have intermittent fasting, alternate day fasting, 24-hour fasting, the 5:2 diet, and endless other variations.
And they all more or less follow the same script:
Instead of spacing your meals throughout the day, you eat all of your calories in a shorter period of time (usually 4 to 10 hours) and fast the rest of the time.
According to some, though, there’s a better mousetrap out there–water fasting.
As you can guess, water fasting involves abstaining from all forms of food or drink except water, and you keep this up for anywhere from a day to several weeks.
You don’t have to look far to find stories of people who swear that water fasting offers all kinds of benefits, including:
Sounds good so far.
The most appealing part is that water fasting is so . . . simple.
All you have to do is stop eating and drinking anything except water, and you’ll look sexier, feel better, be healthier in a few days.
Sure, you’ll be hungry some of the time, but you can handle it. You’re ready.
At least that’s what everyone on the Internet tells you.
You have your doubts, though, too.
It has the stamp of “too good to be true” written all over it, and if it doesn’t deliver on these promises you’ll have suffered for no reason.
And yet . . . what if it only helped you lose a few pounds, or have slightly clearer skin, or gives you a little more energy, wouldn’t it be worth it?
Well, in a word, no.
Water fasting will help you lose weight, but not because there’s something unique about only drinking water for a few days. Chances are also good that you won’t be happy with how you look at the end of your self-imposed starvation experiment.
It’s also not going to “detox” your body, improve your skin complexion, or do much of anything else for you except make you really, really hungry for a few days.
In this article, you’re going to learn why water fasting is an unhealthy way to lose weight and what you should do instead.
Let’s get started.
What Is Water Fasting?
Water fasting involves avoiding any form of food or drink except water for a period of time.
How long depends on who you ask.
Some only do it for a day, others for 3 to 5 days, and still others fast for a week or more.
Unlike intermittent fasting, where you avoid food for a shorter chunk of time (typically 14 to 24 hours), and practice the fast every day or every other day, water fasting typically entails one prolonged fast of several days or more.
It’s normally sold as a kind of “metabolic reset” that you’re supposed to do when you need to kick start fat burning, feel more energized, and make up for whatever other diet and lifestyle sins you’ve made over the past few months.
Use this workout and flexible dieting program to lose up to 10 pounds of fat and build muscle in just 30 days…without starving yourself or living in the gym.
Why Do People Try Water Fasting?
The three main reasons people practice water fasting are as follows:
- To lose weight.
- To “detox” their bodies.
- To slow aging, avoid disease, and improve their health.
It’s obvious that if you don’t eat anything, you’re going to lose weight, but proponents of water fasting claim it offers unique fat burning effects.
Second, like many kinds of fasting, people say that it detoxes your body, improves cellular health, and even fights aging.
Finally, some people do it to avoid disease, live longer, and feel better on a daily basis.
Let’s unpack each of these claims.
Water Fasting Can Help You Lose Weight, But…
Water fasting is often seen as a healthier form of crash dieting.
Now, if you know anything about how your metabolism works, you know that if you forgo any source of calories for a few days, you’re going to lose weight.
Advocates of water fasting say there’s more to the story, though.
They claim that if you want to lose fat as quickly and efficiently as possible, you need to put your body into a state of ketosis, and water fasting is one of the best ways to do this.
And as you’ll see, that’s just plain wrong.
Ketosis is a metabolic process wherein your body gets energy from ketones instead of blood sugar (glucose).
Now, there are two ways to increase ketone production:
- Following a very low-carb diet (typically <30 grams of carbs per day).
- Stop eating for several days.
In both cases, your body has to burn fatty acids for fuel instead of glucose.
What’s more, when most people enter ketosis, they experience rapid weight loss. We’re talking 5 or 10 pounds in a matter of days.
This is why many people believe that water fasting is a better way to lose weight than just restricting calories.
And they’re wrong.
Ketosis doesn’t offer any fat loss benefits over traditional, calorie-restricted diets, and the rise in ketone production during water fasting is just a side effect of extreme calorie and carbohydrate restriction.
In other words, the reason water fasting helps you lose weight isn’t because it increases ketone production, it’s because it decreases your calorie intake.
Okay, fine, you might be thinking, but what about the stories of people losing 5, 10, or more pounds after a few days of water fasting? Some of that must be fat, right?
Well, yes, but not as much as you’d think.
You see, when you cut your carb intake, which is what happens when you go on a water fast, there’s a rapid drop in your whole-body glycogen stores. Glycogen is a form of glucose that’s stored in muscle and liver tissue, and when you stop eating carbs, glycogen levels plummet.
That will cause a small drop in body weight by itself, but here’s why you see such big swings:
Every gram of glycogen is stored with about 3 grams of water. The average man can store 15 grams of glycogen per kilogram of body weight, and regular exercise also increases the glycogen storage capacity of muscle.
So, when you do the math you can see how this could cause rapid, but fleeting, weight loss.
If I were to maximize my carb intake with a few days of refeeding, my body could store close to 1,200 grams of carbohydrate. For argument’s sake, though, let’s say it’s holding more like 800 grams of glycogen, which means I’m also carrying an additional 2,400 grams of water.
All told, that’s about 3.2 kilograms of extra body weight, or around 7 pounds.
And if I were to slash my carbohydrate intake with a ketogenic diet or a water fast, I could lose that much in a few days.
If that weren’t enough, research also shows that carbohydrate intake can influence fluid retention in other ways. Ketones can have a diuretic effect as well, causing you to lose even more water weight than you’d expect from restricting your carb intake alone.
The bottom line is that, on the whole, the more carbs you eat, the more water you’re going to store, and the the more you restrict your carbohydrate intake, the faster you’ll lose weight.
Then, add to that the fact that you won’t have any fiber or other food in your system, which can add up to several pounds, and you can see how water fasting for several days could make you lose over 10 or more pounds of body weight.
That can be gratifying in the short-term, but it doesn’t mean this style of dieting is going to give you the body you want.
Here’s the rub with water fasting:
You will lose some fat, but most of the weight you lose during your fast is going to be water weight, and it will come right back when you start eating normally again.
As soon as you increase your calorie, and especially your carb intake, you’re going to gain weight just as fast as you lost it.
That’s disheartening in and of itself, but the bigger issue is what this does to your body composition over time.
Every time you embark on a multi-day water fast, you’re going to lose some muscle.
It’s hard to say exactly how much, but what we can say is that the longer you fast, the more muscle you’re going to lose.
You can probably get away with water fasting for a day or so without losing any appreciable amount of muscle, but once you push things past about the 24 hour mark muscle loss becomes more of an issue. The longer you go without food after that point, the more muscle you risk losing.
The problems don’t end there, though.
The most glaring problem while water fasting is hunger.
It’s easy to tell yourself that you’ll suck it up. You’ve been hungry before, so you can hack it for a few days.
That’s what everyone says, and that attitude usually comes back to bite them in the end.
Nine times out of ten, forays into extreme calorie restriction end in a massive binge where you gain back all of the fat you lost and then some. At the very least, you’ll wipe out the progress you’ve made, leaving you more frustrated, defeated, and fat than ever.
This isn’t something Youtubers, fitness gurus, or social media “influencers” like to talk about, but it’s a hard reality of extreme calorie restriction.
When you cut your calories low enough for long enough, all you’re going to want to do at the end of that period is stuff your face with as many goodies as you can.
In other words, starving yourself too hard to lose weight in the short term (typically to no avail), can make it harder to stick to future diets in the long run, which is what really moves the needle.
So, the bottom line is that water fasting will help you lose weight, a little of it will be fat, most of it is going to be water, and a lot of it will be muscle.
And when it’s all said and done, chances are good that you’ll have gained back the modicum of fat you lost.
Repeat this process over and over–starving yourself, losing some muscle and fat, and then going back to your normal eating habits, and over time you’ll take on that amorphous “skinny fat” look.
That’s not what you want.
Turns out it’s a lemon in that department, too.
Does Water Fasting “Detox” Your Body?
To answer that question, we have to start at the beginning:
What are “toxins” and how does our body process them?
Well, toxins are poisonous substances that you ingest or inhale. Plenty are manmade, but nature is rife with them, too
For example, caffeine and alcohol are toxins, the atmosphere contains toxins like ozone and nitrogen dioxide, and natural sources of water contain a whole host of dangerous contaminants like arsenic, fluoride, mercury, and cyanide.
The reality is modern living bombards your body with toxins every day, and if it didn’t have an effective way to dispose of them, you wouldn’t last long.
Fortunately, we have an arsenal of complex organic and chemical systems that eliminate harmful substances from our bodies and thus protect against disease and dysfunction.
The liver is the first line of defense because one of its primary jobs is transforming harmful chemicals in the body into harmless ones that can be excreted through urine, sweat, and feces. The kidneys help the body remove toxins and waste products as well.
Champions of water fasting claim that it either helps these processes run smoother, or helps remove toxins from the body through other means.
The fact is, though, that there is absolutely zero evidence for any of these ideas, nor any plausible reason to think that starving yourself for a few days would help remove toxins from your body.
Does Water Fasting Fight Aging?
It won’t help you get the body you want.
It won’t remove toxins from your body.
But, for something so difficult, it must have some benefits, right?
Depending on who you ask, it’s said that water fasting can delay aging, improve your skin tone, and increase your energy levels.
The “proof” for these claims is based on a little-known phenomenon called autophagy, a process where your body breaks down and recycles old parts of your cells that aren’t performing up to par.
In other words, when your body is scrambling for energy, it starts rooting through the “garbage” in your cells for scraps.
And according to many fitness gurus, this slows aging, wards off disease, and improves your health in just about every way you can think of.
What’s the science say about this, though?
Despite the brouhaha about autophagy in some corners of the Internet, we don’t know how much fasting really influences this process in humans, or if it does, how much of an effect that would have on your health over the long term.
Here’s what we know:
Autophagy is going on all of the time anyway, and right now, there isn’t a single study on people showing that fasting is the best way to increase autophagy, or that this offers any health benefits.
Nobody knows, but with so little evidence it’s patently false to say that fasting “slows aging” or offers any other health benefits.
Is Water Fasting Dangerous?
The other side of the aisle says that water fasting is completely safe and you have nothing to worry about.
Both of these groups are wrong.
Short fasts of a day or less probably don’t pose a serious risk to your health or muscle mass, but longer water fasts of several days or more can be dangerous.
The main things you need to pay attention to are:
As long as you drink when you’re thirsty this shouldn’t be an issue, but it could cause problems if you aren’t paying attention.
When some people embark on a water fast, they sometimes go to the other extreme and compensate for their lack of food intake by drinking absurd amounts of water.
While this seems harmless, it can dilute the level of sodium in your blood, causing a condition known as “hyponatremia.”
As long as you drink when you’re thirsty and stop when you aren’t, you probably won’t run into this issue, but it’s a possibility.
If you’re otherwise healthy, you shouldn’t experience major swings in blood sugar during a water fast.
So, if you fall into those groups, don’t try it. Mkay?
Even if you don’t fall into one of those groups, there are better ways to lose weight.
A Better Way to Lose Weight Fast
Losing weight fast is easier than most think.
Eat as little food and do as much cardio as you can for the next month or two, and voila, the pounds fall off.
You may be disappointed in the end, though, even if you can suffer through it.
Well, for the reasons we discussed above. You might be pleased with the number on the scale, but the mirror will paint a different picture.
You may not look as fat as before, but you’re going to look more skinny fat, and that’s not the goal.
That’s why your goal shouldn’t be to “lose weight,” but to “lose fat and not muscle,” and that boils down to just five steps:
Let’s go over each.
1. Use an aggressive (but not reckless) caloric deficit.
Studies show that the only way to lose a significant amount of fat is to eat fewer calories (less energy) than you burn.
You see, the reason you’re carrying excess body fat is, over time, you consistently ate more calories than you burned. And the only way to get rid of that excess fat is to do the opposite: eat less than you burn.
When you do this, you’re in a “caloric deficit” because, well, your energy intake is falling short of your body’s needs. It must get that energy from somewhere, though, and its go-to is body fat.
Now, the larger the caloric deficit, the faster the weight loss, but if you make it too large (by eating too little), you’re going to run into various problems related to “starvation dieting.”
You want to avoid that, but you also want to push the envelope as much as you can. That is, you want to be aggressive in your fat loss efforts, but not reckless. (And you can push things more than you many claim).
To put yourself in that sweet spot, set your calorie deficit at 20 to 25% (eat 20 to 25% fewer calories than you burn every day).
Research shows that this will allow you to lose fat rapidly without losing muscle.
Sure, you might feel twinges now and then, but nothing like what you’d experience with water fasting.
Want to learn more about how to calculate how many calories you should eat? Check out this article.
2. Eat a high-protein diet.
Studies show that eating adequate protein helps you…
The bottom line is high-protein dieting beats low-protein in every way, really, and especially when you’re cutting.
So, what’s the right amount of protein then?
Well, when you’re looking to lose fat, then you should eat about 1 gram of protein per pound of body weight per day.
And if you’re very overweight (25%+ body fat in men and 30%+ in women), then this can be reduced to around 1 gram of protein per pound of lean body mass per day, or 40% of your total calorie intake (whichever number is lower).
Want to know more about how much protein you should eat? Check out this article.
3. Do a lot of heavy compound weightlifting.
When the goal is maintaining (or gaining) muscle mass while losing fat, nothing beats heavy compound weightlifting.
What do I mean by “heavy compound” lifting, though?
And by “heavy,” I mean lifting weights that are above 75% of your one-rep max (weights that you can do 12 reps or less with before failing).
The main reason heavy compound weightlifting is so effective is it’s the best way to overload your muscles, which is the primary trigger for muscle growth.
By lifting heavy weights (and progressing to heavier and heavier weights as you get stronger), you create tremendous amounts of tension in your muscles, and this tells them to grow.
I think you can figure out how this benefits you when you’re restricting your calories for fat loss.
In short, it allows you to minimize muscle loss while dieting, or, depending on your circumstances, even gain muscle while you’re losing fat.
Want to know how to build an effective weightlifting routine? Check out this article.
4. Use high-intensity interval training to burn fat faster.
High-intensity interval training (HIIT) is a type of cardio that involves short, maximum effort sprints, followed by short periods of recovery.
The main benefit of HIIT is that it allows you to lose more fat in less time than traditional slow steady-state cardio.
Another major benefit of HIIT is that it helps preserve muscle better than low-intensity cardio, mainly because you don’t have to do nearly as much to keep making progress.
To be specific, just 2 to 4 HIIT workouts per week, with each lasting just 20 to 25 minutes, is all you need to significantly boost your fat loss.
Want to learn more about high-intensity interval training? Check out this article.
5. Take fat loss supplements that actually work.
I saved this for last because it’s the least important.
Unfortunately, no amount of weight loss pills and powders are going to give you the body you want.
In fact, most fat loss supplements are completely worthless.
But, here’s the good news:
If you know how to drive fat loss with proper eating and exercise, like we’ve just covered, then certain supplements can help speed up the process.
And here are those supplements:
3 to 6 milligrams of caffeine per kilogram of body weight per day.
You can get your caffeine from any source, but if you’re looking for a convenient option that includes several other ingredients proven to boost workout performance, then you want to try PULSE.
0.1 to 0.2 milligrams of yohimbine per kilogram of bodyweight before fasted exercise.
If you like to train fasted, there’s evidence that yohimbine can help increase fat burning during your workouts.
The problem with fasted training is that it can also accelerate muscle loss and take some of the “oomph” out of your workouts, which is why it’s helpful to take something that helps you maintain focus and reduce muscle breakdown before your workouts.
And that’s where FORGE enters the picture. Along with a clinically effective dose of yohimbine, it contains two other ingredients proven to decrease muscle breakdown and help you maintain the intensity of your workouts.
So, if you want to get leaner faster, and especially in the “hard to lose” spots like the hips, thighs, and belly, then you want to try FORGE today.
1 to 2 servings of PHOENIX per day.
Do you want to lose fat faster without giving up coffee and pre-workout?
And without upset stomachs, jitters, nausea, or the dreaded post-workout crash?
Well, PHOENIX is a 100% natural and caffeine-free fat burner that helps you lose fat faster in three ways:
- It increases your metabolic rate.
- It amplifies the power of fat-burning chemicals produced by your body.
- It increases the feeling of fullness from food.
In short, it speeds up your metabolism, helps your body burn fat more efficiency, and helps you control hunger and cravings and maintain high energy levels.
It also contains no artificial food dyes, fillers, or other unnecessary junk.
So, if you want to burn more fat every day and have an easier time sticking to your diet without having to pump yourself full of harsh stimulants or potentially harmful chemicals, then you want to try PHOENIX today.
The Bottom Line on Water Fasting
Water fasting is, at bottom, a dressed up version of crash dieting.
It will help you lose weight quickly, but most of what you lose will be water weight, some will be fat, and a lot will be muscle.
Water fasting doesn’t “detox” your body, slow aging, or help you avoid disease, and it poses a few health risks that the proponents like to downplay.
The good news, though, is that you absolutely can lose weight quickly, safely, and healthily. All you have to do is follow the advice in this article:
- Use an aggressive (but not reckless) caloric deficit.
- Eat a high-protein diet.
- Do a lot of heavy compound weightlifting.
- Use high-intensity interval training to burn fat faster.
- Take fat loss supplements that actually work.
Stick to that plan, and you’ll be much happier with how you look and feel than if you were to try water fasting.
What’s your take on water fasting? Have anything else to share? Let me know in the comments below!
Armistead Legge is the Editor-in-Chief for Muscle for Life and Legion Athletics. He has completed over 100 triathlons and cross-country, cycling, and adventure races, and has researched and written for over a dozen organizations, including the National Institutes of Health. When he isn’t helping people get into the best shape of their lives, he’s lifting weights, riding his bike, hiking, camping, reading, and making delicious food.