From weight-loss supplements to prescription drugs, pharmacies are full of products destined to help lose weight, but their use can come at great expense, both financially and health-wise.

At the 11th International Congress on Obesity hosted in Stockholm, experts were clear when it came to over-the-counter weight-loss supplements: "Save your money; the only thing you are going to lose is your money," said Judith Stern, a professor in the Departments of Nutrition and Internal Medicine at the University of California Davis.

Two studies presented at the congress showed supplements were ineffective.

Thomas Ellrott, a professor at the University of Goettingen in Germany, presented a study in which nine popular supplements, proposing nine different weight-loss solutions, were tested against placebo pills in a controlled trial.

"There are scores of 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," he said.

The participants in his study that took weight-loss supplements lost between two and four-and-a-half pounds, while those taking the placebo lost about two-and-a-half pounds on average.

"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," he said.

Despite their proven lack of effectiveness, the market for supplements ranging from cabbage powder to fiber pills to plant extracts generates a whopping $13 billion per year, said Igho Onakpoya of the Universities of Exeter and Plymouth in Britain.

"People think these supplements are a shortcut to weight loss and may spend huge sums of money on them, but they may end up disappointed, frustrated, and depressed," he said.

For a more effective chance at tackling weight loss, experts recommend turning to prescription drugs, but these are not free from side effects.

An anti-obesity drug that targeted the cannabinoid receptor CB1 had received all regulatory approvals but was then withdrawn from the European market after widespread use showed it carried a risk of psychiatric side effects.

Other prescription drugs have been proven effective, allowing the shedding of up to 10 percent of total body weight, or 18 to 20 pounds per year.

And even these are not risk-free, because of the psychological aspect of fighting against a weight surplus.

"Patients are often victims of their expectations," said Luc van Gaal, of the University of Antwerp in Belgium.

"If the patient is not happy because he's not losing weight fast enough, or he wants to lose more, he starts experimenting, doubling doses ... and then, (prescription drugs) become a health risk," he said, hinting that patients blinded by an obsession to slim down could manage to get their hands on medicine illegally.

Copyright APF