Damien Fereti says Isagenix helped him "gain my life back". The scheme has recorded a 500 per cent increase in activity in New Zealand in the last year.

Rico Gear is doing it. The Bachelor NZ's Alysha Brown was doing it. Hell, even Samuel L. Jackson and Denzel Washington are apparently doing it.

But the concept behind "Isagenix" is ringing alarm bells among health professionals who have concerns over its potential for health complications.

If you don't know what "it" is, you're probably not alone. Social media has recently become awash with endless tributes to a magical, yet nameless, "nutritional cleansing programme", flooded with testimonials from once-curvier friends touting the benefits of the aforementioned invisible product.

Why, you ask, can these people not just tell me what they are using and why? Has a weight-loss company recruited Facebook's newsfeed service, hell-bent on world domination, paying people per photo for mentions of well - nothing?

Enter, Isagenix.

Armed with motivational quotes and pictures of sunrises, the social media frenzy that is "nutritional cleansing and lifestyle programme" Isagenix has firmly made its stamp in New Zealand via its ever-growing horde of loyal followers. Others - more often than not on the receiving end of the inspiration and fitspo memes - are calling for the eradication of the country's "newest cult".

Have you have tried the Isagenix system? Email newstips@stuff.co.nz and tell us your story.

A new day, a new face disgruntled in the "before" photo and smiling in the "after", lifting his or her shirt with triumph, and paling the earlier photo with the bright glow of achievement.

The programme relies on a shake-system, interspersed with Isagenix-branded snacks and drinks, and one meal a day you can choose yourself. It also generates money for those who refer others.

An Isagenix Presidents Pak, the diet's most popular pack. Isagenix has seen a 500 per cent increase in New Zealand activity in the last 12 months.

There are currently 500,000 users and the company is the 27th biggest direct-selling business in the world. This year, they want to grow revenue to more than $1 billion.

It comes as no surprise then that the weight loss giant has seen a 500 per cent growth in activity in New Zealand over the last year, despite launching here eight years ago. New Zealand is the fastest growing market of any of the 14 countries the programme has launched in so far.

Followers of the programme can't seem to tout its advantages enough - Twitter, Instagram, Facebook are all suddenly laden with testimonials. A simple "message me for more information" is usually all that follows. So why not simply tell us what you are using alongside an impressive weight-loss pic?

According to Isagenix, it is not a marketing ploy.

Users simply "talk about the benefits being achieved before talking about the product", Australia New Zealand general manager Angus Love said.

The website centres around testimonials from self-made "Isagenix millionaires", with various forms of status, who ascend to the hierarchal elite of the programme by referring others.

There is little run-down of what Isagenix is and the specifics of the programme. There is, however, a run-down of the elusive Coover family, the founders of the company, which is largely a synopsis of the wealth of each individual.

Isagenix relies on "one-on-one communication", with no retail stores and little overheads, which is why the company can so richly reward their consumers, Love said.

'Isa-Athletes' pose in this photo from the brand's Instagram page. Photo: Instagram/IsagenixANZ

But the entire concept has has concerned health professionals.

ABC Nutrition founder Angela Berrill believes Isagenix is simply the latest offering from the very low calorie diet (VLCD) family, but is "considerably more expensive" than its peers.

Like other VLCDs, the weight was likely to pile back on once the diet was stopped, Berrill said.

"While weight loss can be rapid with VLCDs, there is a potential for health complications ... it is usually recommended that individuals should be medically supervised with frequent monitoring by a health care professional. To my knowledge, this is not a requirement for the Isagenix programme."

The euphoric feeling people say they experience was a direct result of the weight loss – not "anything specific to Isagenix or 'detoxification'", Berrill said.

"In regards to the ability for Isagenix (or any detox diet) to 'cleanse' or 'detoxify' the body, there is no scientific evidence to support this. The body naturally detoxifies itself and removes its waste and toxins every day – that's what our body's organs, such as our liver and kidneys, are for."

Drastically cutting calories resulted in losing water and lean muscle, which was "less than ideal", she said, and led to slowing your metabolic rate to lower than it was than when the diet was started.

"In general, if it sounds too good or too easy to be true, it probably is."

A photo from an Isagenix event in Perth. Photo: Instagram/IsagenixANZ

AUT professor of nutrition Elaine Rush said what "alarmed us the most" was the fact "they brand it about being really healthy saying it eliminates toxins and gains muscle but there's no scientific evidence".

A Google scholar search produces a few articles, most funded by Isagenix with no mention of nutrition. What it does say is that restricting calories and fasting produces weight loss. A study the programme relies on to support their theme – Nutrition backed by scientific research – paints a similar picture. Led by University of Illinois PhD student Krista Varady, the study concludes intermittent fasting and calorie restriction is an effective weight loss technique for women, but makes no mention of nutrition.

It may be marketed as "nutritional", but Rush said the programme was low on "life-giving nutrients" such as iron, vitamins A, B5, C, D and especially calcium.

"It doesn't teach the person how to have a healthy diet or life; they don't learn about what the body needs," Rush said.

"The basic nutrition message should be: eat food. Not too much, but in this case not too little either."

But Love asserts that this is what the "your choice" meal per day is for.

The programme's most popular scheme is its Presidents Pak, a step up from it's flagship 30-day nutritional cleansing programme.

At $948, it is not cheap.

The programme involves six days of "shake days", followed by one "cleanse day".

On a shake day, participants have a shake for morning and dinner, a "healthy, balanced" 400 to 600 calorie meal at midday, and no less than two natural accelerator pills and two digestion-aiding capsules called Isaflushes. Optional snacks such as celery stalks, four cashews or walnuts, or six almonds are allowed.

Cleanse day is an intermittent mix of water and Isagenix drinks. Not to forget, however, three times on that day you can have quarter of an apple, an Isagenix "snack" (condensed whey protein, the size of a pill) or an energy drink.

Love said the price-tag ensured "quality" and worked out to be "less than $30 a day" – which rivalled what a meal cost to produce nowadays anyway.

He reiterates though, that it is "absolutely not a pyramid scheme". Isagenix relied on "network marketing", where referrers receive "commission no different to any other sales person in the world".

And what does Love have to say about the notion Isagenix is not teaching dieters about nutrition?

"I would disagree. We're teaching them to eat the best quality food and Isagenix provides that for one to two meals a day."

'INCREDIBLE' LIFESTYLE CHANGE

It only took two, poignant words for Damien Fereti to decide to turn his life around.

The wake-up call came from a brother he had not seen in several years. The family reunion was marred from the first greeting.

"He came up and gave me this big hug – and I say big literally. When he stood back there was a little bit of disappointment in his eyes ... he said what are you doing, you've put on so much weight. And then he said these two words: You're fat."

Damien Fereti was 176 kilograms before he lost 60kgs on Isagenix. His wife Kelly has also lost 15kgs on the scheme.

The Aucklander was 176 kilograms and miserable. His athletic brother was trim, toned and apparently "glowing".

Years of "losing weight and putting twice as much back on" had left Fereti disillusioned. It was that feeling that compelled him to take his brother's advice and try Isagenix.

"When you're big you don't want to go outside, you don't want to take your children to school and have a kid say to your kid 'is that your Dad, he's fat'," he said.

The first couple of days were "a struggle": two shakes a day and a 400 to 600 calorie meal was a stark contrast from the "huge amounts of food" he was used to consuming on a daily basis.

Seven months later, Fereti has lost 60kgs.

He has made the world championship team for touch rugby and is now one of the fastest on the team. His wife has also lost 15kgs on Isagenix.

Perhaps one of the most telling moments he had reached his transformation goal was when his story came full circle.

"I had a very close friend who thought I was my brother."

For Fereti, the "incredible lifestyle change", will see him follow the programme into the foreseeable future.

"I had this big burden around my shoulders – well, around everywhere really.

"It's helped me gain my life back. I'm no longer looking in the mirror thinking 'what have I done?'."