Despite their bright labels and promising rhetoric, many slimming supplements bought over the counter have little more effect on the waistline than their placebo equivalents, according to a new investigation.
Fat magnets, mobilisers and dissolvers, appetite tamers, metabolism boosters, carb blockers… the list of quick fixes goes on. But new research has confirmed what many health professionals believe and found that scores of slimming supplements claiming weight loss effects have little, if any, real effect.
Two studies presented at the International Congress on Obesity in Stockholm, Sweden, in July, found weight loss pills were no more effective than the placebo supplements they were compared with.
Annual global sales of dietary supplements are well over $14 billion. In Western Europe, sales of weight loss products, excluding prescription medications, topped $1.5 billion (£900 million) in 2009. The weight loss industry in North America is worth over $55 (US$50) billion and Americans spend more than $1.7 (US$1.6) billion a year on weight loss supplements.
The market is huge, but the results are not, suggested Dr Thomas Ellrott, head of the Institute for Nutrition and Psychology at the University of Göttingen Medical School, Germany, who led one of the studies.
“There are scores of slimming supplements out there claiming weight loss effects through all sorts of mechanisms of action… The market for these is huge, but unlike for regulated drugs, effectiveness does not have to be proven for these to be sold,” said Dr Ellrott.
The researchers bought supplements from German pharmacies, changing the packaging and product names to make them look neutral. They then gave 189 obese or overweight middle-aged consumers packets of either placebo pills or one of the nine supplements in doses recommended by the manufacturers.
An average weight loss of 1-2kg for seven of the products matched the 1.2kg weight loss in the group taking the dummy pills.
Dr Ellrott said the results show that not a single product was any more effective than placebo pills in producing weight loss over the two month study period.
A second study presented in Stockholm by Dr Igho Onakpoya of the Universities of Exeter and Plymouth in the UK looked at nine popular slimming supplements, including chromium picolinate, Ephedra, bitter orange, conjugated linoleic acid, calcium, guar gum, glucomannan, chitosan and green tea.
“We found no evidence that any of these food supplements studied is an adequate treatment for reducing body weight,” Onakpoya said.
Several over-the-counter preparations available in Australia are marketed on the basis of having “fat-blocking” qualities, but the Department of Health and Ageing said there is little clinical evidence to support their effectiveness and safety.
In Australia, the Department of Health and Ageing has reported that the benefits of weight loss products are often confused with results of the secondary advice given alongside them. For example, a large number of weight loss supplements on the non-prescription market also recommend an energy-controlled diet and exercise. The benefits experienced by users can sometimes be more to do with this change in lifestyle than the products themselves.
Pennie Jones, an accredited practicing dietician at The Biggest Loser Club, supports this idea. A lot of products come with dietary advice. People follow the advice, which often includes lifestyle changes such as reducing calorie intake and increasing exercise, which will impact their health.
But research suggests diet and exercise alone, compared with diet and exercise taken with weight loss supplements, have similar results, said Jones.
The Department’s latest research into weight loss supplements, Clinical Practice Guidelines for the Management of Overweight and Obesity in Adults, which is currently under review, found that there was not enough evidence to prove their effectiveness. However, it did recommend continued research, suggesting that there might be some hope for these products in the future.
Jones said the idea of a “quick fix or easy solution” with the magic pill gives people a false sense of hope.
Many of the pills are based on the idea that their main ingredient will help the customer lose weight, Jones said. So if a product is caffeine based, it is supposed to stimulate their metabolic rate. Chromium picolinate is an ingredient that is supposed to help the body metabolise glucose, thereby reducing appetite.
“This might work in theory, but when the active constituents are in a concentrated form in a little tablet, the assumption is that they will work in practice. But, in general, the research doesn't prove that these products significantly boost weight loss results,” said Jones.
The idea behind a placebo is that if your mind thinks something will help with weight loss, it keeps you motivated to stick to your weight loss program better.
“So if the product has no adverse effect, then maybe a placebo helping you stick to your weight loss goals is worth it,” she said.
However, some of these products can have adverse effects, for example high levels of caffeine can cause insomnia, dry mouth and headaches, said Jones. “And that is where the negative effects can outweigh the benefits of the placebo effect.”
When a product is promoting a 10-day weight loss result using weight loss supplements, they are setting the consumer up for failure, said Jones. Often the failure of the product to deliver claimed promises can make a person feel like they've failed and therefore negatively impact upon a person's motivation to lose weight, she said.
A person may cease exercising and eating well, thinking the pills are not making a difference in the prescribed 10-day timeframe, so believe there is little point in trying at all.
As the business of weight loss promises in the form of little over-the-counter tablets booms, users are often left disappointed, Dr Onakpoya agreed.
“People think these supplements are a short cut to weight loss and may spend huge sums of money on them, but they may end up disappointed, frustrated and depressed if their weight expectations are not met in the long term.”