Detoxes are a scam; here's why
Let's get one thing straight; a 'detox' is a legitimate medical term used in hospitals under life-threatening circumstances, usually used when there are dangerous levels of alcohol, drugs or other poisons in the body. The medications used to do this are NOT what you're going to find in your herbal tea or 'detox smoothie'. Scam marketers have just co-opted the word detox to sell their product, and make no mistake, at best you're getting an expensive smoothie, and at worse you're taking something that is actively detrimental to your health. Todays 'detoxes' are just a rebranding of age-old rituals of cleansing and purification; these don't work and have zero scientific backing.
Now if you are someone who thought these detoxes work that's fine, it's not your fault that they have been aggressively marketed under the veneer of legitimacy. The blame is on these shady salesmen selling products that only don't work, but may be detrimental to your health. The good news is that these knowing why these products don't work makes it far easier to spot a dodgy product in the future.
The whole basis of detox products is flawed as it claims:
That your body is unable to remove toxins without help
That your body accumulates 'toxins.'
These toxins make you sick
All these claims are wrong.
Lie 1: Your body is unable to remove toxins without help
We already have a pair of highly effective organs whose job IS to remove toxins from our body, the liver and kidneys. You know what happens when these don't work? An ambulance ride to the hospital and likely dialysis and even death. There is no supplement, no 'detox tea' that will remove these supposed toxins. Another great thing about these detoxes is that they never say what is being removed, no toxin is ever named because then they'd have to prove that it somehow is harming you.
Lie 2: Your body accumulates toxins that need to be removed
This is the most common claim made with detoxes, which claims to be able to purify your body through cleansing. Often claims are made that today's diet, environment, smog, GMO 's, and anything in between is causing a 'dangerous accumulation of toxins' that need to be removed. None of this has any basis in reality and anyone who makes these claims shows that they don’t have a basic understanding of our anatomy and physiology.
They seem to view the kidney and liver as filters that gets full of these toxins and need a good cleaning. Your liver isn't a dish sponge, it doesn't need you to come clean it, it does that itself. The liver is self-cleaning with any toxic substance that comes into it gets converted through a bunch of chemical reactions into a substance that can then be excreted through your bile or urine. It doesn't need your help to do this. Believe me, if it did you'd know because you'd be in a hospital with liver failure. The kidney also excretes wastes through our urine, it's constantly filtering our blood, and if it weren't doing its job, then whatever substance is in your blood would stay there.
Lie 3: Toxins cause illness and a detox will help
The marketing claims made by these snake oil salesmen is that toxin buildup causes a variety of symptoms and diseases such as headaches, fatigue, hunger, insomnia and then to really scare you, claims that they'll cause cancer. How do these toxins do this, and what are they? Most often what is in these detoxes is a combination of herbs and some other mystery chemicals that they rarely list, which at best is like scoffing down a bunch of rosemary (better off keeping your herbs to season your foods), and at worst have laxatives in them.
Generally for products that say they will cleanse out the toxins that accumulate in your stomach/intestines (again this has no scientific basis, there is no toxic sludge that builds up). All you're buying is an unregulated laxative which is potentially harmful as well as doing nothing beneficial for your gut. You may as well be flushing your money down the toilet, its an expensive and unhealthy tea that does nothing other than making the seller money.
Detoxes can be harmful
Now that we know that they have no benefit, does that mean they don't cause any harm? It depends on the type of detox, detoxes like a 'juice cleanse', often have a low risk of harm, other than the fact you're having way more fruit than you likely should in a day (if done long enough can cause some severe micronutrient imbalances). More harmful methods are coffee enemas (injecting coffee up your rectum to 'clean' it, needless to say, doesn't work) and laxatives. It’s one thing to purposefully buy a laxative, but most detoxes kits don't even tell you that they contain a laxative, which can lead to severe dehydration and electrolyte imbalance, as well as constipation once you stop using them.
Why do some people feel better after a detox then?
Let's say you feel better after a detox tea, if the tea really isn't doing anything, why do some people feel better?
It's an expensive placebo
You've paid money to use a product that claims to make you feel better. Our expectation of how a drug/treatment will affect us greatly affects our perception of how we feel, and often this happens when we take any drug or treatment, regardless of it is actually doing anything.
Its well documented that placebos are a potential side effect of many treatments, even ones that don't work, and just the taking of a sugar pill with nothing special about it can make people feel better. Its all in your head, and nothing beneficial is happening.
You are paying more attention to your health
The fact you're using a supplement to try improve your health likely means you're paying more attention to your health than normal. A side effect of this is that you will often overall start pursing more healthy behaviours. Maybe you're exercising more, eating better or simply feeling less stressed now you're doing something to 'improve your health.
Finishing comments
Don't waste your money on a product that not only doesn't work, but doesn't even have a potential mechanism to work. Your body is generally great at keeping everything in check, so if you’re serious about improving your health, eat your fruit, veggies and get enough exercise. Don't overcomplicate something that you don’t need to. Very few supplements have any evidence behind them so as attractive at the marketing may appear, chances are you're being sold something that doesn’t work.