Maybe this has happened to you: You invite a friend out to lunch, because
frankly it’s been too long since you had a decent burrito, but they politely decline
-- they say they’re on a cleanse. Turns out they are consuming nothing but juice
for the next three days, because they want to give their digestive system a kind of hard
reset. There are even juice cleanse or juice fast
programs out there, the basic idea is you pay a certain amount per day -- like sixty
bucks -- and you’re provided with a set of juices to drink in a particular order. For the next few days -- usually 3, but sometimes
up to 10 -- you eat no solid food. It’s all juice, all the time, though the
programs also encourage you to drink water. If you’re lucky, you’re getting about
1200 calories a day -- and with some programs, much less than that. Some people also choose to supplement their
fasts with laxatives and colonics, basically enemas. Different programs promise different benefits,
but most claim the same basic thing: that a cleanse will clear out your toxins and “reset”
your digestive system. They’re also often considered a quick way
to lose weight. Except, none of these things are actually
based on science. So, let’s explore how juice cleanses supposedly
work, and compare that with we know about the human body. It’s rare to find a juice fast program that
explains what they mean by toxins, or specifies what any of them are. But the generally accepted definition of toxin
is that it’s a kind of poison produced biologically. And your body does produce harmful byproducts,
like the ammonia that ends up in your urine. But that’s the thing -- it ends up in your
urine, because it’s filtered out, first by your liver and eventually your kidneys. Your body has built-in mechanisms to get rid
of the bad stuff. Drinking juice for a few days isn’t going
to make your liver or kidneys suddenly go into overdrive and clear out anything left
over. Those organs are supposed to be constantly
working -- if they aren’t, that’s what we call liver or kidney failure. These programs also tend to present another
image: that there’s all this extra gunk stuck to the sides of your intestines, and
the best way to get rid of it is to give yourself diarrhea for a few days, and then maybe finish
that off by flushing everything with water. But the human plumbing system doesn’t work
like the one you find in an old house. Instead, waste is constantly moving through
a healthy digestive system. There’s nothing that’s still hanging out
in your intestines from that time you ate a handful of watermelon seeds when you were
five, or even that double cheeseburger you had last month. Food normally takes 24-72 hours to be completely
digested, depending on what it’s made of and how often you have bowel movements. Your body absorbs whatever it can, and the
rest comes out. It doesn’t get stuck to the walls along
the way. But what about the weight loss? Some of these programs do claim to help you
lose weight. Others emphasize that a cleanse should be
for your health, not for weight loss, but also say that cleansing will do things like
“put you on a path to healthier habits.” And people who do juice fasts do almost always
lose weight, but most of it is in the form of water weight. But despite what it sounds like, this water
weight isn’t just the weight you lose from peeing out a bunch of water -- it actually
comes from glycogen in your muscles Glycogen is a form of stored sugar that your
body uses when it’s running low on energy -- like when it’s getting way fewer calories
than usual, all in the form of juice. As soon as you start eating normally again,
your body will replace those glycogen stores and you’ll bounce right back to wherever
you were. On the other hand, for most healthy people,
a juice fast probably won’t hurt them. They almost certainly won’t be getting all
the calories and nutrients they need, but most of these programs aren’t long enough
to do lasting damage. So, if your friend wants to drink nothing
but juice for a few days, odds are they’ll be fine. But they aren’t detoxifying their body or
rebooting their metabolism. They’re just … drinking a lot of usually
very expensive juice. Thanks for watching this episode of SciShow,
which was brought to you by our patrons on Patreon. If you want to help support this show, just
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I had some concerns when I saw this but it is pure sanity.
Hank Green is amazing!
I'll have to watch this later. I have a few coworkers who did juice cleanses like this but could never really explain what to do after or why it's beneficial aside from flushing out toxins, which I'm skeptical of.
That was really interesting :)
I used to think this way! Ugh, I have seen the light my friends, I promise. (Though I do think juices are delicious and will still make my own every once in a while).
This reminds me. My boss told all of us that after sunday she's on some "medically supervised" cleanse (meaning: her Chiropractor prescribed it), and she has to "purify" her body of "toxins" that she's accumulated, and then add things back in to see how her body handles it. I did my best not to tip my hand that I believe that it's all BS. The sad thing? She does not fall into the typical HAES/FA bullshit and actually agrees about CICO... but this... she's 100% sure is true.