If approved by the FDA—a decision is expected by mid-April—the fat-battling drug Qnexa would be just the second prescription long-term weight-loss treatment available in the U.S. (the other, Xenical, was approved thirteen years ago). Meanwhile, a gray market of thinness has emerged, with medication for all sorts of maladies taken for their purported slimming side effects.
Supposed to be used for: Alcoholism, opiate addiction
How it sheds pounds: The body produces opioid-like substances in response to triggers like food. ReVia blocks the brain’s opioid receptors, taking the fun out of eating. “I no longer desired chocolates or sweets,” wrote one ReVia patient at Askapatient.com who used the pill “as a weight-loss experiment.”
Documented losses: 3.7 lbs in eight weeks, by women in a study at the University of Virginia Medical Center
Supposed to be used for: Depression, seasonal affective disorder
How it sheds pounds: By increasing the effectiveness of the body’s natural dopamine— a brain chemical associated with feelings of pleasure—Wellbutrin can decrease appetite. Depression patients sometimes push for Wellbutrin for this reason. “I am now a happy and thinner woman,” noted one drugs.com user.
Documented losses: 12 lbs in eight weeks, as measured by a small U.S. study of overweight and obese women
Supposed to be used for:ADHD, narcolepsy
How it sheds pounds: Ritalin also curbs hunger via dopamine, by boosting levels of the neurotransmitter. Eating-disorder forums are filled with praise: One user compared the Ritalin experience to “[being] like an Energizer bunny … without fainting because I didn’t eat.”
Documented losses: 11% fewer calories were consumed by subjects on Ritalin in a Canadian study
Human Chorionic Gonadotropin
Supposed to be used for: Female infertility, male hormone treatment
How it sheds pounds: Injections of this pregnancy hormone speed metabolism; it’s been used off-label for that purpose since the fifties, but has undergone a revival. Users often pair HCG with a severely low-calorie diet.
Documented losses: “43 pounds total!” bragged one dieter to a Dallas TV station earlier this month
Supposed to be used for: Short-term weight loss only
How it sheds pounds: Phentermine triggers brain chemicals that control appetite. But the drug can be habit-forming, so doctors usually prescribe it for no more than six weeks. Wrote a poster on phentermine.com who’s been taking it for three years: “If I’m off it for a few days, I gain weight.”
Documented losses: 17.6 lbs on average in twelve weeks, by women in a UCLA study
Supposed to be used for: Certain seizures, migraines
How it sheds pounds: Some patients report that Topamax dulls taste buds. It dulls other things as well. “I notice[d] tingling in my toes and feet,” said one user, who lost 80 pounds. “Also I have terrible short-term memory loss.”
Documented losses: 16.4 lbs on average by patients in a study published in the journal Obesity
* Qnexa combines the active ingredients of Topamax and phentermine. After it was rejected by the FDA in 2010 owing to health risks, California doctors started giving the two drugs to patients separately, demonstrating Qnexa’s obesity-fighting potential and leading the advisory panel to decide this time around that the benefits outweigh the risks.