Those colorful, expensive bottles of juice look healthy. But are detox diets good for you? Here’s what the science says — and how a juice cleanse landed one of our nutrition experts in the ER.
Not too long ago, the only people who went on detox diets were Hollywood stars and trend-obsessed editors at fashion and lifestyle magazines.
These days, everyone knows someone who just finished a juice cleanse.
Whether you’ve tried one, you’re considering one, or you’re a trainer (and wondering what the heck to tell your clients when they ask), the big question is:
Are detox diets good for you?
The short answer… maybe, minimally. (And probably not for the reasons you think).
Even more importantly: When researching and writing this article, my wife and I tested a three-day juice cleanse.
Two visits the emergency room later, I can say this with certainty: Any small benefit you might get from a detox diet could be overshadowed by the risk.
More on the emergency room fiasco in a bit. For now…
What is a detox, anyway?
Like other health buzzwords such as “moderation” and “clean”, “dietary detox” has no universal definition.
That’s partly because “nutritional detoxing” doesn’t have a scientific basis.
We’ve seen throughout history that in the absence of science, people are usually left with confusion, superstition, and myth (plus charlatans ready and willing to take their money).
This trend is no different: Despite a lack scientific support for any “detoxifying” dietary process, many “detox diets” have emerged. They take various forms, but most prescribe:
- certain foods,
- special juices,
- “detox teas”, and/or
And some simply promote fasting.
Of course, the imagined purpose of these interventions this is to purge would-be toxins (dirty, yucky, poisonous chemicals) from our bodies. Presumably in the interest of better health.
But, what is a toxin?
By definition, toxins are small molecules, peptides, or proteins capable of causing disease on contact with (or absorption by) body tissues.
Toxins vary greatly in severity, ranging from minor (like a bee sting) to immediately deadly (such as botulinum toxin).
While avoiding bees and deadly bacteria is an obvious best practice, many people in health and fitness are concerned with lifestyle practices that aren’t as clearly threatening.
In the natural world, it’s not as simple as “toxic” vs. “nontoxic”.
Most everything is toxic at some level. We can’t avoid it.
And we shouldn’t try to. Otherwise we’d either eat nothing (because everything contains some level of toxic chemical) or we’d miss out on beneficial toxins.
Wait, what!? That’s right: In relatively small amounts, many toxins can be processed easily — in fact many are actually good for us.
Vitamin A: Overconsumption of this nutrient can cause headaches, drowsiness, and anorexia, among other problems. Of course, in relatively low amounts it’s essential to your health, and especially your vision.
Vitamin B: Get too much, and your neurological and liver function will suffer. In normal amounts, vitamin B helps us convert food into energy.
Phytochemicals: Found naturally in plants, high doses of these compounds may be toxic to the liver, kidney, and intestine. Normal doses of phytochemicals, of course, are celebrated for their anti-cancer and other health-protecting properties.
Lectins: These proteins, which are found in grains and legumes, can bind to cell membranes and damage intestinal tissue if consumed in very large amounts. But in smaller quantities (which you achieve by cooking the food), lectins support basic cell functions, help control inflammation, and may even decrease your risk of certain diseases.
Glucosinolates: Found in cruciferous vegetables like broccoli, Brussels sprouts, and bok choy, high consumption of these sulfur-containing chemicals have been shown to contribute to hypothyroidism. But in reasonable amounts, glucosinolates may protect against cancer in a variety of ways.
Sugar: Too much sugar could become toxic, as measured by blood sugars and triglycerides. In small amounts, sugar is our primary source of energy (plus offer special enjoyment… so go ahead and eat that cookie).
Alcohol: Heavy drinking can increase your risk of many health problems. But generally you can enjoy a glass of wine a day without worrying about toxicity.
Fortunately, the body “cleanses” itself.
If we can’t ever avoid toxins, doesn’t it then make sense to do some sort of detox?
Not really. That’s because our bodies have very robust detoxification systems. Our major organs of detoxification include the:
- digestive tract,
- lymphatic system, and
- respiratory system.
These systems break down chemicals (toxic or otherwise) into other forms we can eliminate via the toilet, sweat, or breathing.
And the body seems to do a pretty good job of this when placed in a balanced (i.e. healthy) environment. More on this to come.
So why do people want to detox?
If the body is so great at self-cleansing, why would anyone consider detoxing in the first place?
Well, some people worry that their lifestyle isn’t as healthy and balanced as it should be.
It’s true that, in general, people:
- overuse medications,
- don’t sleep enough,
- slather chemicals on their skin,
- don’t get enough physical activity,
- over-consume alcohol,
- breathe in smog and ingest other environmental pollutants like heavy metals,
- eat nutrient-poor foods that the body might not recognize as “food”, and
- overuse supplements.
And it’s true that these factors could lead to:
- higher levels of toxins in the body,
- a weakened ability to chemically modify and excrete them, and
- higher risk for disease.
The theory behind a detox diet is that, by giving the body a break, one can atone for lifestyle sins and purge all the nasty chemicals. It’s a health reboot, a fresh start.
But this guilt-rooted logic ignores something important: The best way to “detox” the body is to ramp up your natural detoxification systems and to take good care of them in the long term — not to bypass them altogether, as you do when you’re on a detox diet.
One example: Most detox diets are low in proteins, amino acids, fiber, and probiotics. According to the esteemed Dr. Alan Logan:
“Fasting and low protein diets are counter-productive because our main detox organ, the liver, requires amino acids from protein (e.g. glycine, cysteine, glutamine) in order to support detoxification pathways. Since the assault of man-made chemicals in food, water and our environment never lets up, we need daily detoxification, not some sort of spring cleaning with harsh remedies once per year.”
He goes on to say: “Since many of our toxins find themselves in the gastrointestinal tract, a good daily intake of fiber can help bind them up for elimination. Probiotics, live beneficial bacteria such as that found in yogurt, can also — day in and day out — help to transform toxic compounds in the gut and prevent their absorption.”
Now, it’s important to recognize that health isn’t the main motivation for everyone who does a detox diet. Some have much simpler goals: To lose weight, fit into smaller pants, and radiate good health.
(They might have seen a celebrity touting a cleanse, and the celebrity looked healthy and fit. Maybe if they copy the cleanse, they’ll look healthy and fit too.)
But I can say the following with confidence:
Detoxing to lose body fat doesn’t work.
For a moment, let’s assume that a detox diet will help you get rid of impurities. (It won’t, but let’s assume it anyway).
Does ridding yourself of impurities facilitate fat loss? Nope.
The reason folks lose a remarkable about of weight — quickly — on most detox regimens is because they’re “empty”.
They quickly lose body water, carbohydrate stores, and intestinal bulk. It’s gone during the “cleanse”. But all of it comes back a few hours after the detox ends. Because you can’t stay empty forever.
Interestingly, these folks lose very little fat — unless their cleanse includes fasting for really extended periods (which, if not done carefully, can be dangerous).
In the end, while it feels like a detox is helping shape up your body, it’s a sad illusion. You’re not losing anything that won’t come right back within hours after the end of the diet. And you’re putting your health at risk to support the illusion.
If weight loss is your goal, there are smarter (and more permanent) ways to do it. Ones that are both healthy and sustainable.
Are detox diets good for you?
Given that detox diets won’t rid the body of impurities or lead to real weight loss, are there any benefits?
The only thing one can say positively is that:
A detox diet may encourage you to eat more nutritious foods.
Some detox diets recommend nutrient-rich foods like:
- green tea
- fruit juices
- colorful fruits and vegetables
All of these could, in part, increase your intake of certain nutrients. Some of which might help the body deal with incoming toxins or offer other health benefits.
However, a three-day detox diet won’t move the dial on toxicity (or health) anywhere near as much as maintaining a healthy lifestyle the other 362 days of the year.
Some disadvantages of detox diets.
For most people, the disadvantages of a detox diet are much more numerous than the potential benefit.
Detox diets are often inconvenient.
Any diet will take some effort to organize, and detox diets are no exception. Ironically, you’ll probably never put as much work into eating less as you do into a detox.
People with limited time, money, and resources won’t enjoy juicing fifteen pounds of organic veggies and fruits each day. Especially if they’re feeling weak, listless, or dizzy – some of the most frequently reported side effects of juice cleanses.
Detox diets are often too low in energy.
Meanwhile, most juice diets are extremely low in calories. In fact, some people argue that juicing is just a way to starve yourself and feel good about it.
With the low energy intake you’ll often notice other things slowing down: you may feel colder, or sluggish, or notice digestion taking a while.
Detox diets often swing the pendulum too far.
Many people turn to cleanses in a search for moderation following a period of indulgence.
Yet it’s hardly moderate to eat almost nothing for several days, or to pulverize fifteen pounds of vegetables per day to yield a thick green soup. Can the body even handle fifteen pounds of raw vegetable juice?
Some of the negative side effects that people typically notice on a cleanse could be the result of overload. Their bodies could be working overtime to deal with a noxious cocktail of oxalates, nitrates, etc — all from fruit and vegetable juice.
Ironically, the very “detox” itself could prove “toxic”.
Detox diets may be high in nitrates.
This brings me to one of my own theories. Many people get headaches when they are on juice cleanses — even people who aren’t suffering caffeine withdrawal.
I think this could be due to nitrates.
Many detox juices incorporate lots of celery and beets. Normally, we don’t consume such high quantities of these. Many detox juices are rich in nitrates, which promote vasodilation. Dilated blood vessels can lead to some pounding headaches.
Detox diets may cause blood sugar swings.
Cleanses built on fruit juices can cause major swings in blood sugar — making them downright dangerous for people with diabetes, and potentially risky for many others.
Detox diets can be tough on your GI tract.
The fruit juices used for many detox diets contain very little fiber. Fiber is a cleanser. It’s like a street sweeper for the GI tract; it slows down digestion and aids absorption of nutrients.
There is no credible information saying that the GI tract does better when it doesn’t get solid foods (unless the GI tract is damaged). Instead, the gut does well with pre- and probiotics, glutamine from protein-rich foods, and fiber.
You’ll struggle to get all of these on a cleanse.
Also, many detox diet advocates claim that crud builds up in our intestines, and we need to “cleanse” our digestive tract. If that were true, endoscopies and colonoscopies would reveal this nasty stucco layer in full color… but they don’t.
Again, there’s some irony in a “cleansing” diet that reduces the effectiveness of the body’s natural cleaning crew!
Detox diets are often low in essential fats.
While some less-extreme detox diets allow things like nuts and seeds, hardcore cleanses typically eliminate most fat-containing foods, even healthy fats.
Extreme variations in fat intake — i.e. swinging from high (pre-cleanse) to low (cleanse) to high (post-cleanse celebration) to low (back on the cleanse train again) — can cause trouble for organs that process dietary fats, like the gallbladder.
Detox diets may cause electrolyte imbalances.
Many cleanses involve drinking a lot of liquid (such as water, herbal teas, and/or juices) while removing many foods that contain salts. Some “detox diets” also suggest using diuretic supplements.
This can cause potentially dangerous imbalances in your electrolytes, charged chemicals found in fluids throughout your body. The imbalance is even more likely if overhydration is combined with low energy intake.
In fact, there’s a name for this phenomenon, well-known to health care providers who deal with extreme anorexia, malnutrition, or any medical condition with severely restricted food intake: refeeding syndrome.
To keep operations running when nutrients and energy are low and electrolytes are disrupted, the body may adjust its metabolic environment (for instance, it may deplete cells of minerals to keep blood levels of those minerals stable).
Not only can this affect health during the detox diet, it can cause potentially serious problems when a person on a detox diet (especially a longer-lasting one) starts eating normally again.
Detox diets can create a cycle of restrictive eating and deprivation.
Detox diets — the entire concept of “cleansing”, in fact — can enable feast-or-famine style eating patterns:
- The detox diet starts tomorrow, so I’ll eat a bunch of “toxic” foods tonight.
- On the detox diet now. Not allowed any stuff I enjoy.
- The detox diet ends tomorrow, so I’ll get set to eat all those “toxic” foods I missed!
And so on.
Recognize that thought pattern? It’s the classic dieter mentality. On the wagon, off the wagon, on the wagon, off the wagon, ad infinitum.
It’s always more harmful than helpful. When you think and eat this way:
- You never learn to find the sane middle ground.
- You never learn to prepare real food and real meals that are both nutritious and delicious.
- You’re always in “all-or-nothing” mode. (Usually getting “nothing”, because “all” is really, really hard.)
Worst of all: You never feel truly happy with any of your choices.
Our 3-day juice cleanse:
Complete with unscheduled trips to the emergency room!
Despite the numerous disadvantages I’ve just described, in the name of scientific discovery and self-exploration, my wife and I decided to try a cleanse. Anything in the pursuit of knowledge!
I must admit that things got off to a bad start when my wife reviewed the budget.
“Wait,” she said. “The cleanse is going to cost how much?”
Somewhat sheepishly, I informed her that three days of juice cleansing would set us back $180… each.
Maybe I should have taken the money and mailed it to a non-profit instead. Crap.
Or maybe the cost is part of a placebo effect. Knowing I’m spending this much money on three days of juice might make me feel something awesome.
At 11:01 AM on a Tuesday, our cleanse box arrived. By then, we were getting hungry, especially since they had instructed us to avoid heavy foods (and alcohol and caffeine) the day before we started.
Immediately, I regretted signing up for the “advanced” cleanse. Maybe I should have done the beginners’ version, which included a kale salad and coconut/agave raw macaroon. Mmmmm, macaroons!
But they suggested we could supplement the juicing with whole veggies, fruits, herbal tea, water, nuts, or avocados if we felt like it. I breathed a sigh of relief.
The first juice contained cucumber, celery, kale, spinach, chard, cilantro, parsley, and sunflower sprouts. It had some protein and very little sugar. And it tasted like it had very little sugar.
This wasn’t a shock to me. I’m a fan of leafy greens. My wife, on the other hand, went Incredible Hulk. She couldn’t hide her doubts.
First she gagged. Then she tried to get festive and used a straw, but it didn’t help. Her grimace after each sip was impressive.
(Note: My wife is a confirmed “supertaster,” so the first juice tasted abnormally bitter to her.)
The juice we were drinking was created using a juicing machine to extract only juice from organic fruits and vegetables. I started to think about the difference between whole foods and extracted juices.
What if I ate all of these foods instead? Would that not be equally detoxifying? How would juice, per se, enhance my organs’ ability to eliminate toxins?
The cleanse website claims that I am consuming the equivalent of twelve to fifteen pounds of fresh fruits and veggies each day from six juices — an amount that even I, a certified veggie-lover, wouldn’t be able to consume if I were actually chewing and swallowing all of them.
When we eat solid foods, the foods must go through digestion in order for us to liberate nutrients. When food is pre-chewed by a juicer or blender, this likely decreases the work of digestion.
Maybe you’ve heard of the thermic effect of eating. Certain foods and nutrients have a higher thermic effect. Eat a big steak, there is a lot of work to be done by your gut. You might even get the meat sweats.
Drink fresh kale juice, and you’ve removed fibers and cell walls. All that’s left are liquids and nutrients ready to cross the intestinal barrier and enter circulation.
On the positive side, maybe you’re getting your nutrients faster. On the negative side…
When you’re on a juice cleanse, the nutrients are so accessible that you burn significantly fewer calories via digestion.
As I finished sipping my first juice, I felt satisfied. It quenched my feelings of hunger. So far, so good. Sort of.
Because already, on that first day, I started to get a little bit of a headache. I don’t usually get headaches, and when I do, it’s typically because I didn’t drink enough water.
What’s up with headaches during cleansing? For most folks, it’s simple caffeine withdrawal or blood sugar swings. For others, it might be the effects of increased vasodilation, as I mentioned earlier.
Whatever the cause, my headache eventually disappeared. As I lay in bed at the end of Day 1, all I could think about was how hungry I was. It reminded of my bodybuilding days when I was dieting for a contest.
At 3am 4am, and 5am, I was reminded of that time in my life again. Because I kept waking up with hunger pangs.
My wife had the same experience.
I actually enjoy going to bed at night without an overly full stomach. I think this serves me very well for my health/body goals and it leaves me hungry for breakfast when I wake up in the morning.
But the level of hunger I felt on Day 1 of the cleanse was substantial. And this can make for a crummy sleep.
As it happened, we chose to do a cleanse during the holiday season. So on Day 2, my wife visited her mother’s house for pre-holiday food-prep festivities. This included covering pretzels with chocolate, frosting cookies, and other similar tasks.
During this process, my wife came to an important realization about the power of pre-deciding. Other years, she would have been snacking during cookie preparations, but since she was committed to the three-day cleanse, she didn’t feel conflicted about eating.
She had pre-decided not to have any cookies. Not an option, not a problem.
Meanwhile, I tried a light workout. Just a simple circuit with some weights and conditioning drills. About midway through, I started to reek of ammonia. Good ol’ breakdown of body proteins due to a low energy intake.
One of the juices on the detox plan included probiotics. Probiotics can help to populate the GI tract with beneficial bacteria, which in turn can help our digestive systems work more smoothly.
Nevertheless, towards the end of day two I was not feeling particularly “cleaned out”. I did feel hungry, but not like I had prepped for a colonoscopy.
In the early afternoon I started to get a strange twinge/pinching sensation in my lower right abdomen. I don’t know if it was my GI tract on hyperdrive or an inevitable (non-cleanse related) appendicitis. But it was strange.
I thought some apple slices and almond butter would help, but they didn’t.
Later in the afternoon, my wife and I both got a deep chill. Winter in Boston is cold. And apparently, winter in Boston while drinking only green juices is even colder.
That evening, bundled in a sweater, as I sipped one of my juices, I began another quest for credible research and resources in support of detoxing and juice cleansing.
Surely I’d find something out there to convince me that this cleanse was a great idea?
Well… not exactly. Because at this point, there just doesn’t seem to be a strong scientific case in support of detox diets.
Let’s put it in context. Most of the articles I write take months of research. There are so many studies, so much literature to review and sift and consider. There’s no way I could get through it and make sense of it all in one night.
But with this article, I found only a few credible sources to review. The research took a couple of hours.
Here are the conclusions: One study demonstrated that eight days of juice fasting can have mixed results on blood fats. And another case series showed that a whole-foods cleanse resulted in weight loss and improved blood lipids.
That’s about it.
Now, beyond controlled research, there are plenty of anecdotes in support of detoxing, especially from companies selling detoxing kits.
But the vast majority of unbiased health and nutrition experts say that a simple eating pattern built around whole, nutritious foods trumps a 100 percent juice cleanse every time.
My wife and I wake up tired after two nights of poor sleep. Each night, we’ve been kept up with a bad case of the “growlies”. (This is one of my client’s terms for excessive hunger.)
The one bright spot at this point in the cleanse is that we’ve both had minimal bloating. I wonder how much of this has to do with a lack of solid foods. Maybe in the future, taking more time to chew completely would lead to this same feeling.
So our stomachs are flat. But we’re tired, grumpy, and hungry. We’re also freezing cold.
And we really, really dislike the taste of two of the juices. We can only tolerate four of the six juices today.
In the late afternoon, we start to reflect on the cleanse. For sure, we feel lighter; there’s nothing moving through our intestines. But we’re ready to transition to solid foods.
On the night of day three we begin to taper off of the cleanse with double bacon cheeseburgers and a couple of pints.
No, only kidding. We eat a light dinner of soup, salad, rice/quinoa, and beans.
My wife and I agreed that we wouldn’t do a juice cleanse again.
If we want to take a break from eating for whatever reason, we’ve decided that a 12-24 hour water/tea fast will do the trick.
Call me crazy, but I’m not sold on the idea of spending $60 for juice each day.
And the high financial outlay wasn’t the only difficulty we encountered with the cleanse. As I mentioned, my colon and GI tract were on overdrive starting on day two.
To my surprise, this continued for about two weeks after the cleanse and even led to some weird abdominal pain, an appendix inflammatory episode, and a trip to the ER!
That wasn’t exactly what I had in mind when I began this adventure.
As for my wife, she was extremely hungry for about five days after the cleanse, and actually became dehydrated with low potassium. She even passed out… and wound up in the ER.
Seriously! Both of us had to visit the ER. After a three-day cleanse! (I hate to imagine what might have happened if we’d tried a longer one.)
Needless to say, our post-cleanse time was eventful (and not in a good way).
Obviously this was just our experience, and I’m not sure if it was directly related to the cleanse, but I do think it’s worth sharing.
Lying next to the CT scanning machine at 4am, I tried to remind myself that the purpose behind cleansing is to increase overall wellness. It’s not supposed to make you feel miserable.
What the heck happened?
Now, whenever anything bad occurs in our house, we joke, “It’s because of the cleanse.”
What’s the future of cleansing?
Maybe we’ll eventually discover that there’s something really powerful and health-promoting about drinking juice extracted from pounds and pounds of fresh produce, but right now, we just don’t know.
If you detox, and your life is better for it, cool. But based on what I know about nutrition, the human body, and the world – I don’t recommend it.
Detoxing doesn’t appear to be a route to a healthy lifestyle. Instead, most people detox for a few days and then want to go back to their normal way of living.
What if we just aimed to eat and live in a way that supports the body’s natural detox – all the time?
We already know the main dietary risks in North America, which include excess calories, processed sugars, fats, and salt. Simply cutting down on these would improve our health and functioning.
We can do this by eating the highest quality, freshest food possible, paying attention to body cues, and not overeating.
We don’t need a magical weekend juice cleanse.
What to do next:
Some tips from Precision Nutrition.
Here are 10 steps you can take each day to help your body do its natural detox job.
- Eat reasonable amounts. If you’re eating too much, you’re probably accumulating more toxins than your body needs. Eating one cookie instead of six is a detox diet. Slow down and chew your food. We all have “anatomical juicers” – our teeth and our stomachs. Use them as they’re meant to be used.
- Eat plenty of plant foods, and choose organic options when possible. Veggies and fruits contain compounds that can help the body deal with all of the incoming chemicals. Organically raised plants and livestock are generally lower in the types of things you don’t want, such as pesticides, hormones, antibiotics, etc.
- Stay lean. Certain fat-soluble compounds can accumulate in body fat. Less body fat = less real estate for potentially problematic chemicals.
- Drink enough fluids, including water and tea. And use a water filter. The kidneys are major organs of elimination for fluids. But don’t overdo it: Fluid intake needs to balance our bodies’ electrolytes. Generally you can avoid overhydration by not drinking more than one liter of fluid per hour.
- Allow a little extra time between dinner and breakfast. During brief periods of fasting (such as overnight), our bodies clear out cellular debris. If you finished eating dinner at 7pm, maybe you could eat breakfast at 7am. This gives the body a 12-hour break from food for every 24-hour cycle. This might also improve your sleep, which is another critical factor in allowing your body to appropriately recover.
- Get outside in the sun and fresh air each day. Not only do we synthesize vitamin D from the sun, but we can breathe fresh air into our lungs and hear the sounds of nature. Good ol’ Mother Nature.
- Exercise regularly. Getting your blood flowing will help circulate good stuff where it needs to be, and clear out waste products more effectively.
- Limit unnecessary dietary supplements. Supplements don’t automatically equal health. And some might just be another burden for the body. Make sure each supplement in your cabinet serves a purpose.
- Cut down foods that you know are bad news for you. You may know that some foods don’t agree with you, whether because they make you feel bad physically, because of how they make you feel emotionally, or because you don’t like the person you become when you eat them. Consider moving away from these foods gradually. (Eliminating them all at once may work, but you may find the same problem with all-or-nothing thinking that characterizes detox diets.)
- Check your cosmetics. Our skin is our largest organ; each day we lather hundreds of chemicals into it. These then enter our blood and circulate throughout the body. If you want to burden your body with fewer chemicals, check your body products.
More complex than you thought?
Dedicated “detoxing” isn’t necessary? Toxins can be good for you?
The field of nutrition is sometimes complex. At Precision Nutrition, it’s our mission to make it easier to understand — and to help people develop workable strategies for eating well.
Women and men in our Precision Nutrition Coaching programs learn how to optimize their food intake and activity levels to protect their health in sustainable, long-term ways.
Coming Wednesday, April 5th.
If you work in health and fitness (or would like to) and want to be able to address client questions (“Should I do a detox?”) like a pro, check out our Precision Nutrition Level 1 Certification program; it kicks off soon.
Important: Since we only take a limited number of students each time we offer the program, and it sells out every time, the best strategy is to add your name to our free presale list.
Getting on the list gives you the chance to sign up for the certification 24 hours before everyone else. Even better, you save big on the cost of the program.
[Of course, if you’re already a student or graduate of the Level 1 Certification, check out our Level 2 Certification, an exclusive Master Class for elite trainers looking to perfect their nutrition knowledge and coaching techniques].