Beware of Fraudulent Weight-Loss ‘Dietary Supplements

Look for potential warning signs of tainted products, such as
promises of quick action, such as “lose 10 pounds in one week”
use of the words “guaranteed” or “scientific breakthrough”
labeled or marketed in a foreign language
marketed through mass e-mails
marketed as an herbal alternative to an FDA-approved drug or as having effects similar to prescription drugs

http://www.fda.gov/ForConsumers/ConsumerUpdates/ucm246742.htm