17-year-old Kylie Jenner "can't leave the house" without this weight loss product.

Ask your average 17-year-old woman what she can’t leave the house without, and she’ll usually say something like “my phone” or “my wallet”. Makes sense — in 2015, these are considered essentials.

For Kylie Jenner, however, the answer is “weight loss detox tea”.

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The youngest member of the Kardashian fan seems to be following in big sister Kendall Jenner‘s footsteps, by using ‘teatoxing’ as a way to stay slim. Yesterday, Jenner posed for an Instagram shot with a packet of FitTea, which she captioned: “Couldn’t leave the house without my @FitTea detox….”

So far, that photo has amassed 1.2 million likes and hundreds of comments.

Jenner isn't the first celebrity to jump on the teatox bandwagon. Her sister Kendall revealed earlier this year she drinks "like, 12 cups a day" of detox tea in preparation for her runway appearances, while E! presenter Giuliana Rancic reportedly followed the Ultimate Tea Diet in the leadup to her wedding.

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Sarah Hyland, Scott Disick, Vanessa Hudgens and Lindsay Lohan have also spruiked detox tea programs on their personal Instagram accounts. “Love my @booteauk teatox! So easy to use on the move,” Lohan wrote in a caption last month.

If you haven't heard of the teatoxing trend before, it's exactly what the name suggests — a 'detox' program involving specially formulated teas that claim to offer a host of health benefits. Some of these teatoxes last a week, while others recommend 28 days of use. In most cases, you order the products online.

Often these tea programs are marketed on weight loss benefits. Jenner's product of choice, FitTea,  claims on its website that it's "The best fat loss tea and dieter's tea". Nutritionist and dietician Arabella Forge says this marketing is concerning, because many detox teas are known to contain laxative ingredients that could induce weight loss  in a potentially damaging way.

"Certain herbal ingredients have quite a strong laxative effect, and that can do quite a bit of damage to the body particularly if you're consuming it in excess," Arabella explains.

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"It might make you feel that  you're losing weight because you're going to the toilet all the time, but that can actually have quite dire consequences — it can affect your bowel and how it functions, and long term implications as well. Definitely, this kind of product can be taken to extremes." (Post continues after gallery.)

Indeed, some users might lose weight after embarking on a teatox, but Arabella says this isn't necessarily attributable to the tea itself; it could simply result from that person becoming more interested or proactive about their overall approach to health and eating well.

However, people don't only use teatoxes for the 'weight loss' aspect. Some brands boast clear skin, improved digestion, increased energy and less bloating positive outcomes of their teas.

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Again, these aren't necessarily legit.  "I'm not sure exactly what the legalities are, but the claims are very strong for the kind of product it is. I think they would be very difficult to back up," Arabella says.

One look at the reviews for Jenner's tea of choice suggests there are some unpleasant side-effects. "10 mins after [I drink it] I get this upset nauseous feeling, almost as if I'm going to be sick. It's unbearable," one commenter writes. "I got the 28 day detox one. I drank it for 5 days and every single day I felt nauseous! I finally stopped because I could not take it any more," another adds.

For other reviewers, the detox simply didn't product the outcome they were after. "This product was expensive without any results," one says. 'Kiara' writes: "It didn't work like how I thought it would when everyone hyped it up ... I won't be wasting any money on 'supposedly' weight loss teas, pills, shakes etc."

That's not to say there aren't nutritional benefits associated with drinking herbal tea in general. It's a healthier alternative to hot chocolate or sugary energy drinks, and it contributes to your daily intake of fluids. However, Arabella says you'll get all of these benefits from supermarket herbal teas, or even home brews, with the added bonus that they're much less costly than the 'detox' variety.

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"You don't have to go on a fad diet to get the benefits of herbal teas. There are a lot of things you can grow at home that you can make into nutr tea. Things like mint, parsley, sage — they're all herbs that are reasonably nutritious and you'd have to consume an extreme excess to do any damage," Arabella suggests.

Then there's the other issue at hand — the fact Kylie Jenner is hooked on this product, and recommending it to her followers, at just 17 years of age. (Post continues after gallery.)

Interestingly, the FitTea website states that while their product is suitable for people aged 13 and above (hmmm), customers under the age of 18 require parental permission to purchase their teas. Does this mean Kris Jenner is on board with her daughter's questionable diet?

"It's not a very healthy message [Kylie's] putting out to that age group. That demographic are probably the most vulnerable to fad diets and to extreme dieting. Your body's still developing at that age, so it's really important that that age group are eating well and nourishing their bodies," Arabella says.

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It mightn't sound quite as appealing as 'this magical tea will make you lose weight!', but as always, Arabella says the best way for young women — or people of any age, really — to go about being healthy is to make sensible food and lifestyle choices in the long-term.

"I don't think there's ever going to be a quick fix in one product. The best approach is a more moderate approach to plain ol healthy eating, making sensible choices about food and choosing things that are nutritious and eating regular meals and not skipping meals."

Have you ever fallen for a dangerous diet fad?