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ScienceMay 14, 2018

I took NZ weight loss pill Calocurb and the side effects were… disturbing


Developed by New Zealand plant scientists and funded in part by a $20 million MBIE grant, Calocurb is being marketed as a major step forward in appetite-control treatment. But is it all it’s cracked up to be? Weight loss industry expert Andrew Dickson gave it a try.

Calocurb was launched here in New Zealand in early April this year; it is due to ‘go live’ in the American market in the next few weeks. The PR hype surrounding the New Zealand launch easily captivated me and almost immediately I purchased a bottle ($60 for a one month supply) and gave it go.

Why did I buy it? Why did I try it? It would be easy for me to claim I did so as a kind of auto-ethnographic research project, using myself as a test case and then writing about it for academic purposes. But it is far more complicated – and more personal – than that. The truth is that I am feeling really vulnerable to diet industry hype at the moment; this is how my anxiety tends to show itself. 2018 has been a rough year so far, with tumultuous family revelations, work frustrations, and issues with ACC and special needs education. Calocurb appeared in the middle of this and it provoked some familiar feelings in me: both compulsion and revulsion. And so, as with so many diet ‘supplements’ before, I had a crack.

What got me particularly about this product was the suggestion of clever Kiwi-based science. The so-called ‘bitter brake’ compound Amarasate, a trademarked extract of hops, is the key to Calocurb. Supposedly Amarasate triggers satiety signalling via the release of certain hormones – there is a nifty little video about it here. I grabbed a particularly compelling screenshot of one image:

Here you can see the red and blue dotted lines going up, supposedly signaling your brain to stop eating. What it doesn’t show, however, are the dotted lines going down. And they’re important, because for me, Calocurb’s ‘bitter brake’ was for me more like a gastrointestinal accelerator.

It appears that I am not alone in experiencing digestive distress after taking Calocurb. In a now deleted blog post (you can find a cached version here) the people at Calocurb responded to the most common questions from customers, including one about possible side effects:

“The side effects that some customers might experience are generally associated with a laxative effect…”

Tell me about it, Calocurb! I had a similar experience after eating unpasteurized milk products in Calcutta. To be fair, while the diarrhoea lasted for a few days in India, it was only an issue for a couple of hours after my fourth dose of Calocurb. But in both cases I sat upon the porcelain throne wondering if the people in the stall beside me would think I was attempting to run a deep bath.

Calocurb’s solution to such delicate issues? “To start with, avoid taking calocurb on a completely empty stomach…”

Wait, what?

So in order for their calorie-restricting chemical to take effect, you need to first ingest calories, in order to avoid blowing your intestinal system into smithereens. OK. As an American colleague of mine commented, “cholera is also a superb weight loss intervention. What will they think of next?”

To be fair to the Calocurb scientists they suggest that this ‘side effect’ passes as your body gets used to the Amarasate compound.

When you dig down, the details of Calocurb are actually really interesting – and paradoxical. On one hand, there is the elegance of science, the process of painstaking lab research looking for particular compounds, and then the detailed work of figuring out how and why they might be effective. New Zealand taxpayers partially funded this research to the tune of $20 million via the Ministry of Business, Innovation and Employment. It ultimately produced two things – the Amarasate compound itself, and a ‘patented capsule’ (one of the type that has actually been in use for some time) that allows the Amarasate to be delivered closer to the small intestine than a normal capsule would. It does this by taking longer to release its contents, the aim being the targeted delivery of the compound to where it is ‘most effective’.

On the other hand is the familiar crass consumerism of the diet industry. Calocurb is being sold using classic diet industry rhetoric with just a hint of all-natural marketing hype:

“Goodbye craving, hello you”

“It’s time to meet the new you”

“Here are your little capsules of willpower”

“Go au naturel with just three plant-based ingredients”

My research career is all about the weight-loss industry, which I have renamed the ‘weight-anxiety industry’. Calocurb fits squarely into this multi-billion dollar enterprise. Its website (Calocurb is only sold online) is light on important details, it’s backed by only one incredibly preliminary research trial which is yet to be published in a peer-reviewed academic journal, and as far as I can tell there has been little or no consideration of long-term efficacy or safety, aside from relying on safety data from other hops extracts. This is characteristic of diet industry magic pills – they catch you with outlandish claims, like those above, and ask you to trust them, because… Science!

However we simple consumers have a bit of power here in the form of Medsafe, which protects us by determining the safety of the medicines we take. And Calocurb has already come to its attention – last week Medsafe warned that someone had experienced a ‘life-threatening’ allergic reaction after taking it. There is no mention of Calocurb on the Food Safety NZ register for compounds Generally Regarded as Safe (GRAS). This despite the following claim on Calocurb’s FAQs page:

“A panel of five independent scientists recognised calocurb as GRAS (Generally Recognized As Safe)”

I asked Calocurb about this, and to their credit they sent me the paperwork which does indeed show that five scientists agreed that Amarasate was GRAS as a food additive or supplement. However there is no mention in the report of Calocurb itself, or the ‘patented capsule’ by which the Amarasate gets delivered directly to your unsuspecting small intestine.

None of the five independent scientists are from New Zealand; most are based in the US. It may be the case that Calocurb never had any intention of getting regulatory approval in New Zealand at all, because they have decided that the product can be categorised as a dietary supplement – and our regulatory processes for dietary supplements are pretty minimal.

My personal opinion is that Calocurb is not a dietary supplement, because it clearly has “a stated or implied therapeutic purpose” and should therefore be subject to the Medicines Act 1981. But that is obviously not my call. Over to you, Medsafe.

The reality of the weight-loss industry

The sad part of all this is that for the average consumer, there’s basically no health benefit associated with weight loss attempts. I know! It seems crazy doesn’t it? But the evidence is now clear: the majority of people who attempt to lose weight by dieting or using weight loss pills will regain that weight and their health will not improve in the long-term; more likely it will suffer.

Is Calocurb a game-changer in terms of weight loss? I doubt it, because we know that biological appetite and hunger are not the same. It may well be possible to impact appetite – certainly the diet industry have been claiming the ability to do this for years – but hunger is an altogether different beast. Hunger is love, it is desire; we eat for people, to please them, to care for them. We eat to belong, to comfort ourselves or to celebrate. That isn’t appetite.

I do however think that Calocurb has the potential to make lots of money, because weight-anxious consumers will try almost anything.

Perhaps there is a miracle obesity cure out there in the plant kingdom – something that will level the bell curve of human body mass and create a world of people all with BMIs neatly between 20 and 24.9. But I’m not going to hold my breath.

Instead I hope that the scientists involved at least pause for thought here as they read the words of a colleague of theirs from the social sciences. Perhaps it is time to let go of the weight loss fantasy; we have so many pressing societal problems that your scientific knowledge and skills could be better utilised trying to solve.

How Calocurb consumers can get involved

There is a wonderful group based at Otago University called the Centre for Adverse Reactions Monitoring (CARM). Calocurb also mention them on their ‘health professionals’ page. If you or anyone you know has had an adverse reaction to Calocurb then send them an email ( and let them know. I’ve done it. We need better data on the side effects of this drug, because it seems to me we cannot rely on Calocurb to gather it and make it freely and easily available.

The Spinoff’s science content is made possible thanks to the support of The MacDiarmid Institute for Advanced Materials and Nanotechnology, a national institute devoted to scientific research.

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