Two studies presented on Monday at the International Congress on Obesity in Stockholm, Sweden, found that the so-called slimming supplements were no more efficacious than the fake supplements they were compared with.
“There are scores of slimming supplements out there claiming weight-loss effects through all sorts of mechanisms of action. We have so-called fat magnets, mobilisers and dissolvers, as well as appetite tamers, metabolism boosters, carb blockers and so on,” said Dr Thomas Ellrott, head of the Institute for Nutrition and Psychology at the University of Gottingen Medical School, Germany.
For their research, Ellrott’s group tested nine popular supplements against placebo pills in a randomised controlled trial. These include L-Carnitine, polyglucosamine, cabbage powder, guarana seed powder, bean extract, Konjac extract, fibre pills, sodium alginate formulations and selected plant extracts.
The researchers bought the supplements from German pharmacies, changed the packaging and product names to make them look neutral and rewrote the information leaflet inserts to eliminate the product name from the text.
They gave 189 obese middle-aged consumers packages of either fake pills or of one of the nine supplements, each week for 8 weeks. Average weight loss, they found, was between 1 kg and 2 kg across seven of the products, while it was 1.2 kg in the group getting the placebo pills.
“We found that not a single product was any more effective than placebo pills in producing weight loss over the two months of the study, regardless of how it claims to work,” Ellrott said.
In a second study presented at the congress, Dr Igho Onakpoya of Peninsula Medical School at the Universities of Exeter and Plymouth, UK, conducted the first systematic review of all existing systematic reviews of clinical trials on weight loss supplements. The analysis summarised the state of evidence from reviews of studies involving nine popular slimming supplements.
“We found no evidence that any of these food supplements studied is an adequate treatment for reducing body weight,” Onakpoya said.
“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.”