Do You Really Need a Detox Cleanse? Science Says No

Juice cleanses, liquid fasts and other detox plans promise to help us push the restart button on our body. And that’s something all of us wants, really. Who doesn’t want to undo all the bad decisions they’ve made in the past year with a 7-day detox plan? I know I do!

With detox diets, you can lose weight, cleanse your colon, kick toxins out of your body and give your hardworking organs a rest. Or so they claim.

Let’s take a more in-depth look at these claims, and try searching for the scientific, peer-reviewed evidence behind them:

Claim No. 1: Detox diets will eliminate toxins from your body

In the medical world, the term “detoxification” refers to the removal of toxic substances from the human body. Toxic substances in this context means life-threatening levels of poison (like drugs and alcohol). [1]

The detox diets claim to rid your body of the accumulated toxins from the environment, the food and drinks you’ve ingested, as well as the random stuff you come in contact with daily. But here’s the thing, your body does that just fine by itself. Your skin, kidneys, lymphatic system, gastrointestinal system, as well as your liver make up a very sophisticated and versatile detoxification system, better than any “detox” fad. [2, 3]


“There is absolutely no scientific evidence that our body needs to fast or detox in order to cleanse itself from toxins. These diets are so popular because they feed off the fear that our environment is full of chemicals, and therefore detoxes are necessary. But our bodies have their own built-in defense system—such as our lungs, liver, kidney, and gastrointestinal tract—to help eliminate toxins.” — Heather Mangieri, RD, CSSD, a spokeswoman for the Academy of Nutrition and Dietetics. [4]

And what “toxins” are they referring to anyway?

Everything is a chemical, and all chemicals can be toxic. It is the dose of these chemical which determines whether they’re toxic. For example, you may take a 400mg Vitamin A tablet daily, which is probably good for your body, but if you up that dose to half a bottle each day, you’ll most likely be damaging your liver [5].

Your body’s main detox machine is your liver, which cleans itself by converting toxic substances and eliminates them in bile or the kidneys [6]. Toxins do not accumulate in your liver so there’s really no scientific need for liver cleansing (unless you have liver disease). There’s also been little or no scientific evidence in support of detoxification methods. [7]

“Some detoxification proponents claim that intestinal sluggishness causes intestinal contents to putrefy, toxins are absorbed, and chronic poisoning of the body results. This “autointoxication” theory was popular around the turn of the century but was abandoned by the scientific community during the 1930s. No such “toxins” have ever been found, and careful observations have shown that individuals in good health can vary greatly in bowel habits,” — Stephen Barrett, M.D. [8]

Claim No. 2: Your colon accumulates gunk, so you need to flush that out 

According to colon cleansing products and rituals, poop accumulates into a toxic waste buildup, which can lead to a series of health issues if not cleared. However, according to Dr. Ranit Mishori, an associate professor of family medicine at Georgetown University School of Medicine in the US, the claims make no physiological sense at all.

“The cells that form the lining of the colon are shed every 72 hours. This cell turnover means stool doesn’t stick to intestinal walls, and so-called toxins don’t build up in the colon and get released into the bloodstream, as cleansing proponents contend.” — Dr Ranit Mishori [9]


In the past decades, physicians have performed colon examinations on millions of patients only to find fresh, pink flesh. No poop in sight on the colon walls, hence the theory that there’s a toxic waste buildup in your colon holds no water [10].

In fact, colon cleanses have been associated with negative outcomes such as nausea, cramps, mineral imbalance, infection, etc. [11]

Claim No. 3: Detox diets help you to lose weight

While you will most probably lose weight doing a detox diet (due to the low caloric intake), most of that is water weight. Which means that once you start eating normally again, you’ll gain it all back.

Detox diets can't help you keep weight off. It's your daily eating habits that determines that.
Detox diets can’t help you keep weight off. It’s your daily eating habits that determines that.

Many studies have shown that fasts and low-calorie diets lower your body’s basal metabolic rate because it’s struggling to conserve energy. Once you start eating normally, rapid weight gain follows. [12]

Claim No. 4: Your digestive system needs a break from all the work you’re giving it

Advocates of liquid cleanses (like juice fasts etc) believe that by consuming only liquids for a period of time allows your digestive system to rest from all the work you’ve been giving it. Fortunately for us, your digestive system doesn’t need a break (except for the period between meals). It’s an intricate system designed to work round the clock, whether or not you eat or drink anything.

“Your entire body was designed to be on the job around the clock. When you go on a fast of eating nothing, your body thinks it’s starving. It does everything it can to protect you and starts to conserve fat and calories. In starvation mode, your metabolic rate slows down, and muscle tissue gets burned preferentially over fat.” — Nancy L. Snyderman, M.D. [13]

But Detoxing Works! My Friend Told Me He Felt Much Better After a Cleanse! 

Sure, many stand by their claims that their latest detox diet or fast helped fix their complexion, improve their mood and feel 10 years younger. Unfortunately, anecdotal evidence is not hard evidence, and there hasn’t been any credible published evidence that these detox products / diets can help your body function any better [14].

Detox cleanses might work for some thanks to the placebo effect, which isn’t necessarily a bad thing. However, if you’re attempting to go on a detox programme, you should be aware of the possible side effects such as malabsorption of vitamins, electrolyte imbalances, diarrhea and more.

Bottom Line 

As much as we would like them to exist, there are no quick fixes to all our health woes. There’s no magical juice cleanse or herbal tea that’ll miraculously make us healthy. The best and only way to improved health is to maintain a healthy lifestyle every single day.

This means sleeping adequately, exercising regularly, and eating nutritious meals filled with veggies, fruits, lean protein and whole grains.


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