Putting weight-loss supplements through their paces
In the eight-week trial, 189 overweight and obese people took a placebo or one of nine weight-loss supplements according to the manufacturer's directions, including L-carnitine, polyglucosamine (chitosan), cabbage powder, guarana seed powder, bean extract, konjac extract (glucomannan), fiber pills, sodium alginate formulations, or "selected plant extracts."
At the end of the study, the people taking weight-loss supplements lost two to four pounds and the people taking placebo lost two to two and half pounds, a difference that wasn't statistically significant. "We found that not a single product was any more effective than placebo pills in producing weight loss, regardless of how it claims to work," said lead study author Thomas Ellrott, head of the Institute for Nutrition and Psychology at the University of Gottingen Medical School, Germany, in a news release.
Looking to future research
Given the demand for interventions and the vast industry built around weight loss, it is important that researchers continue to explore the effects of such supplements. This study raises many questions that will be interesting to understand if the findings are accepted for publication, including details on what the "selected plant extracts" were, and why cabbage powder (and possibly others, depending on what the "selected plant extracts" are) was included when it doesn't appear to be marketed specifically for weight loss, at least in the US.
We know from research on using supplements to manage a wide range of health conditions, intake amounts and use in combination with other supplements and interventions (such as exercise and dietary changes) can have a measurable impact on a supplement's effects. So it will be interesting to see whether the manufacturer's recommendations followed in this research represents optimal usage.
In the US, weight-loss supplements are regulated as food by the Food and Drug Administration, guided by the "Dietary Supplement Health and Education Act." DSHEA guidelines restrict manufacturers from making health claims other than approved "structure-function" claims (for example, calcium supports bone health). Because of this regulation, even when research does exist that might be the basis for more effective usage, manufacturers are not allowed to print information on packaging, which means that following "manufacturer's instructions" in most supplement use is unlikely to be optimal. It is unclear whether Germany has similar packaging guidelines.
No magic bullet
It should come as no surprise that the only sure way to lose weight and keep it off is to change the way you eat and to exercise more. Claims that any supplement, medicine, or any other product can help you lose weight without doing these things should be met with a healthy dose of skepticism.
If diet and exercise alone haven't helped you lose weight and you're thinking about taking a supplement, consult an unbiased source before you buy to see what research has said so far and to get realistic expectations of how the mechanisms claimed by manufacturers might support your goals. For example, the Healthnotes database has gathered this science about some of the products that were reviewed in the study: many have been shown to have conflicting results. Some have shown promise if a specific amount is taken but not with a lesser amount, or if used in conjunction with a diet and exercise program.
While we wait for more details to emerge from the German study, we can focus on what we do know about weight loss: It isn't going to happen without some work--lasting results rely on meaningful lifestyle changes. The recipe for weight loss is as easy as (not eating) pie: Eat Less + Exercise More = Weight Loss for Life
(Proceedings of the International Congress on Obesity 2010)