Weight loss supplements are big business. Fat burners, fat blockers, metabolism boosters, appetite suppressants – these are just some of the popular kinds of pills, potions and herbal concoctions that fly off pharmacy and health food store shelves. But how effective are any of these products? That’s what I’ll explore in this podcast.
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Episode transcript
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Weight loss supplements are big business. Fat burners, fat blockers, metabolism boosters, appetite suppressants – these are just some of the popular kinds of pills, potions and herbal concoctions that fly off pharmacy and health food store shelves. But how effective are any of these products? That’s what I’ll explore in this podcast.
Links referred to in the podcast
Episode transcript
To access the full episode transcript, go to the following link and select the individual podcast episode and then click on the ‘Transcript’ tab https://thinkingnutrition.buzzsprout.com
Connect with me
Instagram: doctimcrowe
Facebook: Thinking Nutrition
Twitter: CroweTim
Weight loss supplements are big business. Fat burners, fat blockers, metabolism boosters, appetite suppressants – these are just some of the popular kinds of pills, potions and herbal concoctions that fly off pharmacy and health food store shelves. But how effective are any of these products? That’s what I’ll explore in today’s podcast.
Losing weight is hard. Keeping it off is even harder. And even with a limitless number of diets available to try, the current high rates of overweight and obesity are testament to the failure of most approaches. In the search for a shortcut to weight loss, many people turn to over-the-counter herbal pills and potions.
With their seductive claims of ‘metabolism boosting’ and ‘fat melting’ featured prominently in their promotion, it is no wonder that herbal weight loss supplements seem like an attractive option. But how effective are they? A simple answer based on an observation would be that if any of these products made dramatic inroads for weight loss, the word would be out by now. But with shelves groaning with new products to try, this very likely points to the lack of benefit of most of them.
With its focus on the herbal weight loss supplement sector, and here we are talking about things like green tea, Garcinia cambogia (which is a tropical plant native to Indonesia), white kidney bean, ephedra, yerba mate, liquorice root and mangosteen, a major scientific review published in 2020 looked at the safety and efficacy of these supplements for weight loss.
In all, 54 randomised controlled trials were included in the review where the herbal supplement was compared head-to-head against a placebo for weight loss. And I’ll link to the review in the show notes. https://pubmed.ncbi.nlm.nih.gov/31984610
For the findings, the news was bleak. Only one, yes just one, of the herbal supplements (which was white kidney bean) showed a statistically significant benefit for weight loss when given as a single supplement. And even then, it was a very tiny 1.6 kilograms which is not of any great clinical significance as greater than 2.5 kg of weight loss is considered clinically meaningful. Other supplements did show a benefit, but it was usually based on having three or fewer clinical trials of poor quality to support them.
That review was published last year and was mostly focused on herbal supplements. So, now, and published only in the last month, a broad systematic review has cast its net over the whole gamut of dietary supplements and alternative therapies for weight loss. A staggering 315 randomised-controlled trials were included which covered 14 different dietary supplements and therapies. And I’ll link to this review in the show notes. https://pubmed.ncbi.nlm.nih.gov/34159755
Why I focus so much on RCTs in this podcast, especially in the area of weight loss, is because you need to be sure a particular supplement can have a direct and independent effect on weight loss outside of either intentional or unintentional lifestyle changes a person may make because they are starting a new treatment. Having a matched control group who don’t get the treatment is the best way to make a valid comparison. And for weight loss pills and potions, it is normally possible to mask the treatment so a person doesn’t know if they’re getting the active ingredient or a placebo.
So, what did this major review find? Firstly, most of the studies in the review were considered of lower quality with bias a likely issue. Of the just 16 percent of studies that were considered of having a low risk of bias, barely 1 in 3 of them could identify a meaningful weight loss benefit. So, you can see how poor the evidence is already and makes most claims you hear of ‘clinically proven’ from promoters flogging these weight loss supplements as utterly worthless as the actual weight loss they will cause is of not much significance and usually based on cherry-picked, poor-quality studies.
Let’s dig a bit deeper into some of the interventions studied in the review.
For chitosan which is a fibre-like substance extracted from the outer skeleton of shellfish such as lobster and is claimed to be a ‘fat blocker’ in the gut, of 9 trials, just 1 had a low risk of bias and it found a weight loss of 2.3 kg over 6 weeks.
Then there was ephedra taken with caffeine and for the 10 trials that were considered of low risk of bias, 5 reported a change in weight ranging from 0.3 to 4.9 kg. The problem here is that ephedra, which is a herb that has strong stimulant properties, is a banned substance in countries such as Australia and the US because of safety concerns.
For green tea, 16 trials had a low risk of bias, and of these, just two reported a change in weight of tiny 1.5 to 1.7 kg.
Chromium, which I covered in last week’s podcast mostly with the focus on blood sugar and diabetes, also is a popular supplement promoted for weight loss. And just one trial from the three in the review that had a low risk of bias found a weight change and it was just a tiny 1.4 kg over 10 weeks.
Garcinia cambogiam, guar gum, calcium and vitamin D, CLA, pyruvate and white kidney bean were also studied and the narrative here is pretty much the same as what I’ve already covered.
The complementary therapies of mindfulness and acupuncture were also looked at. For mindfulness, out of 22 trials, just two had a low risk of bias, and neither of those reported actual weight changes. So, of the rest, just 6 studies found evidence of weight loss.
And finally for acupuncture, out of 45 trials, just two had a low risk of bias, partly from the difficulty of doing truly blinded studies in this area as you kinda know if you’ve been jabbed with a pin or not, and of these studies, neither showed a significant benefit on weight loss.
So, not a great endorsement for most therapies, but really, the wider community probably already knew this as if any of these pills, potions and therapies showed outstanding success then the secret would be out and you’d also hear credible professionals giving some endorsement to them.
Downsides
There are some downsides here to consider as well apart from the mostly failed weight loss and cost as there is evidence that people who take weight loss supplements are less likely to control other areas of their eating – a well-described psychological effect known as moral licensing.
Putting weight loss effects aside, medical researchers are now asking the question if a fixation on using a ‘pill’ to solve a weight problem can come with some unintended side effects.
Borrowing from psychological theory, the presence of one perceived positive health behaviour may give license to follow a less healthy behaviour. It is called moral licensing where a ‘good’ act boosts the likelihood that more liberal morals are applied to other behaviours. A classic example would be someone who goes to the gym and then allows themselves to over-indulge in unhealthy reward treats afterwards.
Could turning to weight loss supplements which are a clear statement of a weight loss goal behaviour mean that a person is more likely to let other aspects of their diet slip? To answer this, 74 healthy adults, who were unaware of the research question, were randomly allocated to take either a weight loss supplement or a placebo pill. What the participants didn’t know, was that every pill was a placebo pill.
After giving ratings on the size, shape, colour and texture of the pill they took, each person then completed a questionnaire measuring how they thought they were making progress in their weight loss goals. After the questionnaire, each person was offered a reward drink (which was a bubble cup tea) where they could choose how much sugar they wanted in it.
The final stage of the experiment involved each person taking part in a ‘taste test’ of different types of confectionery where they could consume as much as they wished.
So how did the people who were told they were given a ‘weight loss supplement’ fare compared to those who knew they were taking a placebo? People taking the phoney weight loss supplement consumed 29 percent more of the confectionery in the taste test and asked for almost double the amount of sugar in their drink. This same group of people though were more likely to report that they were making greater progress towards their weight loss goals.
Breaking the results down further, the researchers could see that the knowledge that they were taking a weight loss supplement was driving the participants’ perceived progress towards weight loss goals. And the more people reported that they were moving towards their goals, the more confectionery they ate in the taste test. I’ll link to this full study in the show notes https://pubmed.ncbi.nlm.nih.gov/24096084
The results of this study do not stand alone. Previous research has found that people taking multivitamins are more likely to slacken off in other important health behaviour areas.
Summary
So, let’s wrap this up. Before you hit play on this episode, I suspect most of you knew already that most of the weight-loss supplement market is just a bottle full of empty promises. The evidence continues to remain poor that herbal and dietary supplements will make any significant in-roads for weight loss. And where a benefit is seen, it is usually very small.
Due to the poor regulation of such supplements, promoters of herbal preparations will likely continue to make outlandish claims about their products without any consistent and credible evidence to support them. And there will always be new players in the market as they move onto the next and biggest thing. Just save your money and don’t buy into the quick-fix mentality that these supplements can lure you in with.
So that’s it for today’s show. You can find the show notes either in the app you’re listening to this podcast on if it supports it, or else head over to my webpage www.thinkingnutrition.com.au and click on the podcast section to find this episode to read the show notes.
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I’m Tim Crowe and you’ve been listening to Thinking Nutrition.