Losing weight is hard, but many weight loss supplements promise to make the journey easy. Unfortunately, there's little high-quality research to back these claims, a new study shows.
Hundreds of weight loss supplements like green tea extract, chitosan, guar gum and conjugated linoleic acid are being hawked by aggressive marketers. And an estimated 34% of Americans who want to lose weight have tried one, according to the researchers.
"The temptation is great because someone has a megaphone, but you don't need a celebrity endorsement and/or splashy headlines to tell you how to lose weight. The medical establishment will speak loudly and clearly when there's something to say," said study co-author Dr. Srividya Kidambi, an associate professor and chief of endocrinology and molecular medicine at the Medical College of Wisconsin.
To find out if 14 weight loss supplements and/or alternative therapies like acupuncture do what they claim, researchers identified 315 randomized-controlled trials, which are considered the gold standard in clinical research. Of these, 52 studies were deemed unlikely to be biased. Just 16 studies showed differences in weight between participants receiving treatment and those in the placebo arm.
The weight loss in these studies ranged widely, from less than one pound to just under 11 pounds. Weight loss was not seen consistently for any one weight loss treatment, and many had conflicting results, with some studies showing weight loss and others showing no such effect.
The studies included in the review looked at chitosan, a complex sugar formed from the hard shells of shellfish; ephedra or caffeine; green tea; guar gum; the tropical fruit extract Garcinia cambogia; chocolate/cocoa; conjugated linoleic acid, a natural substance produced in the gut by digestion of fats; white kidney bean (Phaseolus vulgaris); and calcium plus vitamin D, among others. Alternative weight loss therapies evaluated in studies included acupuncture, mindfulness, hypnosis and meditation.
"The dietary supplement industry is a Wild West of herbs and over-the-counter pills that have a lot of claims and little to no evidence supporting those claims," said study co-author Dr. Scott Kahan, director of the National Center for Weight and Wellness in Washington, D.C. "We all want a magic pill, but dietary supplements aren't the magic pills that they are marketed to be."
There are things that are proven to help you lose weight and keep it off, Kahan said.
"Support from a dietitian, nutrition education and, in some cases, medication or weight loss surgery can all aid weight loss," he said.
The study authors issued a statement calling for tighter regulation of supplements and more high-quality studies to assess the risks and benefits of weight loss supplements. The study appears in the June 23 issue of Obesity.
Their work comes on the heels of another study that found weight loss supplements mostly ineffective. That research was presented virtually last month at the European Congress on Obesity and published in the International Journal of Obesity.
In the United States, supplements aren't regulated in the same way that pharmaceuticals are so there is no way to know if you are actually getting what you're paying for, said Kidambi.
Most weight loss supplements won't cause any harm, but many peddle false promises, she said. "If supplements take the place of diet, regular exercise and behavior changes, they will harm you in the long run," she added.
Some supplements sold online may be laced with ingredients that are harmful and banned in the United States, Kidambi noted.
Weight loss supplements can also be pricey, she said.
It's buyer beware when it comes to weight loss supplements, agreed Dr. Louis Aronne, founder and director of the Comprehensive Weight Control Program at New York-Presbyterian Hospital/Weill Cornell Medical Center in New York City.
"There is very little research demonstrating that currently available supplements produce significant weight loss," said Aronne, who was not involved in the new study.
Andrea Wong is senior vice president of scientific and regulatory affairs at the Council for Responsible Nutrition, a Washington, D.C.-based trade group representing the supplements industry.
Wong, who has no ties to the research, pointed out that the new study did not include all of the dietary supplements on the market today, some of which may aid in weight loss efforts.
"Consumers should be wary of products that promise to make weight loss easy and to always talk to a health care practitioner for advice on responsible supplement use and weight management programs," she said.