Intestinal cleansing: what it involves and what is supported by evidence
The essentials at a glance
In medicine, “intestinal cleansing” means preparing for an examination, for example before a colonoscopy. In advertising, the same term means a cleanse intended to free the body from something. Evidence is lacking for the second meaning: According to the German Nutrition Society, there are no meaningful human studies on the effectiveness of detox diets.
This text separates the different meanings instead of dismissing the need behind them. Anyone searching for “cleanse the intestines” has a reason: abdominal pressure or an advertising promise, along with the desire to lose weight. Each deserves an evidence-based answer, not a recommendation for a cleanse.
Chapters 1 to 3 clarify the term. Chapter 4 explains how laxatives deplete the body of fluids and salts. The table in Chapter 5 compares the variants. From Chapter 9 onward, the focus is on what a gut flora test can and cannot reveal about the composition.
What to expect in this article
1. What the intestine does every day anyway
2. What is supported by evidence about “cleansing” and “detoxifying”
3. What experts mean when they say intestinal cleansing
4. What laxatives cost the body
5. Four things that may be called intestinal cleansing
6. Why a cleanse still feels good
7. Widespread and evidence-based: three statements fact-checked
8. When rebuilding the gut has a tangible basis
9. What a gut flora test shows before and after a cleanse
10. What you can do now
Frequently asked questions
Sources
What the intestine does every day anyway
Before anyone considers cleansing the intestines, it is worth looking at what happens there without any intervention. According to the Institute for Quality and Efficiency in Health Care (IQWiG, 2026), the large intestine is about 1 to 1.5 meters long. Its main task is unremarkable: “In the large intestine, even more water together with salts is removed from the liquid digested food.”
This is not a minor detail. In the workplace analogy, the intestine is less a waste bin than a recovery facility: it retrieves from what passes through whatever the body can still use.
1–1,5 m
Length of the large intestine. It removes water and salts from the digested food. IQWiG, 2026
5
Ways in which a healthy body eliminates unwanted substances: liver, kidneys, intestines, skin, and breathing. DGE, 2018
3×
“Diarrhea is defined as having very soft or liquid stools at least three times within 24 hours.” IQWiG, 2023
none
“Overall, there are no meaningful human studies investigating the effectiveness of detox diets.” DGE, 2018
The figures already capture the entire conflict. On one side, an organ that reclaims water and salts. On the other, a cleanse promise that aims to interrupt precisely this process.
What is supported by evidence about “cleansing” and “detoxifying”
The word “detoxify” has a kernel of truth, just not the one being advertised. In its 2018 overview, the German Nutrition Society (DGE) writes: “A healthy human body can ‘cleanse’ itself by excreting unwanted substances through the liver, kidneys, intestines, skin, and respiration.” The process exists. It simply does not need a product.
Key message
Eliminating unwanted substances is an ongoing task performed by the body, not a state created by a cleanse.
The most common objection is: “Everyone talks about toxins, and you say they do not exist?” A different answer is more honest. None of the sources reviewed for this article uses the term “toxins” at all - neither the DGE, nor IQWiG, nor the gastroenterology professional society. Anyone advertising with it is using a word that does not occur in professional terminology.
Documented source
“There is currently no scientific evidence for the effectiveness of so-called detox or detoxification diets”
German Nutrition Society
“Detox Diets,” DGEinfo 3/2018
This is not a marginal remark from a single source, but the assessment of a professional society. And it does not say that cleanses must be harmful. It says that the claimed effect has not been scientifically established. The distinction matters when you are standing in front of a shelf right now.
What experts mean when they say bowel cleansing
In medicine, “bowel cleansing” is an established procedure with a clear purpose. In 2023, the German Society for Gastroenterology, Digestive and Metabolic Diseases and the German Society for Endoscopy and Proctology wrote: “Thorough bowel cleansing is necessary to prepare for an examination, such as a colonoscopy or an operation.” It is therefore a means of enabling the examining person to see anything at all. It is not a health goal in itself.
How medical bowel emptying works
According to the same source, “PEG-based substances (polyethylene glycol solutions)” and “saline laxatives (osmotic laxatives)” are used. PEG stands for polyethylene glycol, also known as macrogol; saline products are salt solutions. Both belong to the category of laxatives; the source says nothing more about them.
That is why it also says, “Without sufficient fluids, the bowel cannot be cleansed properly.” The process usually begins “the day before the examination,” and the goal is precisely described: bowel cleansing is successful “when the stool is liquid, light-colored, and clear like chamomile tea before the examination.” This describes a condition for an endoscopy, meaning an examination using a camera inside the bowel, not a promise of well-being.
Anyone who enters “bowel emptying” into a search box ends up with this medical procedure and reads it as instructions for use at home. That is exactly where the confusion begins.
At a glance: three meanings of bowel cleansing
First, medical preparation before an examination, ordered by a doctor and limited in duration. Second, the cleanse product purchased commercially, which promises a cleansing result. Third, the home remedy that someone uses on their own initiative. Only the first meaning has a defined purpose and a defined endpoint.
What laxatives cost the body
Any remedy that makes the stool watery comes at the same cost. In 2023, IQWiG described it in relation to diarrhea: “Anyone with diarrhea loses fluids and electrolytes. That is why the most important thing is to compensate for this loss.” Electrolytes are dissolved salts such as sodium and potassium.
This explains why medical bowel cleansing is explicitly tied to fluid intake and takes place as preparation for an examination. Anyone who creates the same effect at home without this framework assumes the same risk without the same support.
When to see a doctor
Blood in or on the stool
This should be investigated regardless of whether you have taken anything. It is not a case for waiting and seeing.
Fever or severe abdominal pain
Either of these together with diarrhea is a reason to visit a medical practice promptly rather than continue observing.
Weight loss that you cannot explain
Unintentional weight loss is a sign that belongs in a medical consultation, not in a cleanse plan.
Circulatory problems during a cleanse
Dizziness or weakness after several watery bowel movements is consistent with the described loss of fluids and electrolytes (IQWiG, 2023). Stop and seek medical advice.
The warning signs are preparation for a conversation, not self-diagnosis. They tell you when you should hand the matter over to a healthcare professional.
Four things that can be called bowel cleansing
The same two words refer to completely different processes. The table places them side by side and states for each what it is based on. Where there is no evidence in the sources reviewed for this article, it says so instead of filling the gap with an assumption.
| What is meant | What is proven | What it costs the body | What a gut flora test reveals |
|---|---|---|---|
| Medical bowel cleansing before an examination | The purpose and procedure are described: preparation for a colonoscopy or surgery, using PEG solutions or saline, that is, osmotically acting laxatives (DGEP, 2023) | Fluids and electrolytes, that is, dissolved salts such as sodium and potassium (IQWiG, 2023). Hence the doctor's instructions on drinking | Nothing about the success of the preparation. It does not measure the degree of cleansing |
| Detox or cleansing treatment purchased commercially | “Overall, there are no meaningful human studies investigating the effectiveness of detox diets.” (DGE, 2018) | If followed strictly over the long term, “a nutrient deficiency, for example in protein and fat” and an increased risk of eating disorders (DGE, 2018) | The composition of the flora before and after - without judging whether the cleanse was worthwhile |
| Home remedies such as enemas, Glauber's salt, or psyllium husks | No evidence in the sources reviewed for this article of a cleansing effect. That is why no instructions for use are provided here either. | Where they have a laxative effect, the same loss of fluid and electrolytes applies (IQWiG, 2023) | Only the state of the flora at the time of sampling, not the effect of the product |
| Change your diet: fiber and variety | No evidence in the sources reviewed for this article of a cleansing effect. Fiber consists of indigestible plant components that reach the large intestine | No loss of fluid or salts through purging, because nothing is being purged | The composition of the flora measured weeks or months apart, as a point of comparison |
If you want to choose between variants rather than clarify the term, the separate article on gut restoration can help. It focuses on rebuilding after a strain, not on the promise of cleansing.
Why a cleanse can still feel good
Someone who has undergone a cleanse sometimes reports feeling better afterward. That should be taken seriously, and it does not contradict the evidence. The DGE gives the most likely reason for the visible part of the success: “The rapid weight loss is very likely due solely to energy restriction.” Energy restriction simply means that significantly fewer calories enter the body during this period.
And the scales show something different from what was hoped for. According to the same source, the short-term success is “primarily due to a reduction in water, not body fat.” In line with the DGE overview, a very low energy intake also lowers the basal metabolic rate, which promotes the yo-yo effect after the cleanse ends.
There is also the part that no study measures: Anyone who consciously eats and drinks for several days pays attention to their body. That awareness does not disappear just because the product does nothing. You can have it without the product. Anyone who came here expecting to lose weight can find the longer version in the article on bowel cleanses and weight loss.
This is the obvious objection: “If it helped me, why should I care about the studies?” Understandable. But you are paying for the part that works with the very price of the part that has not been proven.
Common and supported by evidence: three statements in the fact check
These statements appear in this form or in similar forms in advertising copy and conversations. None of them is foolish. Each can be checked against a source.
Fact check
Commonly claimed
“Toxins build up in the intestines over the years.”
Documented
None of the specialist sources reviewed here uses the term. Instead, they describe ongoing elimination through the liver, kidneys, intestines, skin, and breathing (DGE, 2018).
Commonly claimed
“A bowel cleanse makes fat melt away.”
Documented
The short-term success is based “primarily on a reduction in water, not body fat” (DGE, 2018).
Commonly claimed
“After the cleanse, the gut flora is clean.”
Documented
“Clean” is not a described state for gut flora. In the sources, the term clean applies only to intestinal contents before an endoscopy: liquid, light-colored, and clear like chamomile tea (DGEP, 2023).
Anyone who wants to know what “flora” and “microbiome” actually mean can find the basics in the article What is the microbiome?.
When building up the gut has a tangible rationale
Not every discussion of gut flora is a marketing claim. There are situations with a clear rationale, and the strongest of these is the period after antibiotic therapy. The article Building up gut flora after antibiotics explains how to interpret this.
The difference from a cleansing regimen lies in the direction. The regimen aims to remove something. Building up aims to let something in and requires time rather than a cleanse on an empty stomach.
Your gut cleanses itself every day. The question is what you give it for that purpose.
Your gut cleanses itself every day. The question is what you give it for that purpose - and no cleanse product answers that question; what you regularly put on your plate does.
What a gut flora test shows before and after a cleanse
This is where the second objection arises, and it is justified: “If cleanses do not do anything, then your test does not do anything either.” The honest answer distinguishes between two things. A gut flora test from mybody®x (MYBODY Lab GmbH) does not measure effectiveness. It describes a state, specifically at the time you take the sample.
The composition of the gut flora is shown: bacterial groups, pH value, and fungal colonization. The pH value indicates how acidic or alkaline the intestinal contents are. Fungal colonization means the extent to which yeasts can be detected in the sample. No more than these three details are intentionally provided here because the full list of additional parameters has not been released.
Before a cleanse, such a report is a starting point; afterward, it provides a point of comparison. What it is not belongs here just as clearly: It does not evaluate a cleanse, measure toxins, or provide a diagnosis. The article on Understanding diversity in a microbiome report explains how to read such a report; the comparison of tests related to a gut cleanse explains which test is even suitable in connection with a cleanse.
At-home stool test
Gut microbiome test | Essential
Shows the composition of your gut flora: bacterial groups, pH level (a measure of acidity or alkalinity), and fungal colonization (detection of yeasts). As a starting point before a program and for comparison afterward. It does not evaluate any program, measure toxins, or provide a diagnosis.
What you can do now
If you came here wondering which program is right for you, this text has not answered that question - because the sources reviewed have not answered it. What it does answer is the question before that: Which of the processes do you actually mean when you say “intestinal cleanse”?
Before a colonoscopy, the medical practice specifies the procedure, and it involves fluids. Symptoms that persist for weeks belong in a conversation with a medical professional; the warning signs above tell you when it is urgent. And if you want to know your own condition, a sample from everyday life provides a data point.
It all began with the word “cleanse.” That is even true - except the body does it itself, and it already does so today.
Frequently asked questions
Is bowel cleansing before a colonoscopy the same as a detox program?
No. According to the German Society for Gastroenterology, Digestive and Metabolic Diseases and the German Society for Gastrointestinal Endoscopy (2023), medical bowel cleansing is “necessary as preparation for an examination (e.g., colonoscopy or surgery).” It generally begins the day before the examination, follows medical instructions, and ends with the examination. By contrast, a detox program pursues a health goal for which, according to the German Nutrition Society (2018), scientific evidence is lacking.
Do you lose weight through an intestinal cleanse?
The number on the scale goes down, but body fat does not. In 2018, the German Nutrition Society wrote that the short-term success was “primarily due to a reduction in water, not body fat,” and that the rapid weight loss was “very likely attributable solely to the energy restriction.” In essence, according to the same overview, a very low energy intake lowers the basal metabolic rate and thus promotes the yo-yo effect after the diet ends.
What should we make of home remedies such as Glauber’s salt, enemas, or psyllium husks?
There is no evidence in the sources reviewed for this article that such products “cleanse” the intestines. That is why there are no instructions or dosage information here. What can be said is that, insofar as a product has a laxative effect, the described loss of fluids and electrolytes, that is, dissolved salts such as sodium and potassium, applies (IQWiG, 2023). Anyone wishing to use such products should discuss this with a medical professional beforehand.
When does frequent bowel movement count as diarrhea?
In 2023, IQWiG defined a clear threshold: “Diarrhea means having very soft or liquid stools at least three times within 24 hours.” This threshold is also useful for a cleanse because it indicates when your body is in a state in which it loses fluids and electrolytes. If blood in the stool, fever, or severe abdominal pain occurs as well, you should see a doctor.
Can a gut flora test show whether a cleanse worked?
No. A gut flora test shows the composition of the flora at the time of sampling: bacterial groups, pH level, and fungal colonization. Two samples taken weeks apart provide a before-and-after comparison, nothing more. The report does not reveal whether a change was caused by the cleanse, a changed diet, or something else entirely. It does not evaluate a cleanse, measure toxins, or provide a diagnosis.
Next step
Measure first, then decide
If you're interested in what your gut flora currently looks like, a stool sample collected at home is the easiest way to find out. It tells you nothing about cleanses and everything about your starting point.
View the gut flora microbiome test Read the basics firstRead more
You might also be interested in this
What can go wrong when collecting a sample at home and how to avoid it.
How people plan a bowel cleanse and how the individual components can be evaluated.
Sources
- German Nutrition Society: Detox diets, DGEinfo 3/2018 (as of 2018) - dge.de
- German Society for Gastroenterology, Digestive and Metabolic Diseases, Endoscopy and Proctology: Bowel cleansing (as of 2023) - dasgastroenterologieportal.de
- IQWiG, gesundheitsinformation.de: How does the intestine work? (as of 2026) - gesundheitsinformation.de
- IQWiG, gesundheitsinformation.de: Diarrhea (as of 2023) - gesundheitsinformation.de
All statements about detox diets, the body's self-cleaning process, and weight loss are based on [1]. The procedure and purpose of medical bowel cleansing come from [2], the information about the large intestine from [3], and the threshold for diarrhea as well as fluid and electrolyte loss from [4]. Product information comes from the mybody®x product pages and was checked on 09/09/2026.
mybody®x Editorial & Expert Team
Gut health Microbiome
Behind this text is the editorial and expert team at mybody®x, which checks every statement against the cited expert sources. The people who contribute to it are listed on the authors page.
Published on 09/09/2026 · Last updated on 09/09/2026
Our products are not intended to diagnose, treat, cure, or prevent diseases. The content is for general information only and does not replace medical advice, diagnosis, or treatment. Reference ranges depend on the laboratory, method, and age - the information on your report is always authoritative.
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