Until this past July, it had been more than a decade since the FDA had approved a weight-loss drug.

Previous attempts to treat obesity with a medication haven’t ended so well. Remember “fen-phen” (fenfluramine/phentermine)? It was pulled off the market in 1997, as was dexfenfluramine (Redux), because both were associated with heart problems. Sibutramine faced the same fate in 2010. And the promising drug rimonabant was never approved in the US because it was linked to suicide. The only other drug on the market right now that’s approved for weight control is orlistat (Xenical, alli), which blocks a fat-digesting enzyme in the intestine.

To treat obese patients, doctors have mainly turned to surgeries that alter stomach anatomy so fewer calories can be absorbed. But those operations can have serious side effects, including death. And they don’t always lead to long-term weight loss.

So the recent news that the FDA has approved two new weight-loss drugs got a lot of attention. Could these be the solution to America’s growing problem with….well, growing?

I checked in with a top obesity researcher to discuss these new drugs…


Belviq and Qsymia are the newly approved medications. Both are approved only for obese adults (a BMI of 30 or higher) or very overweight adults (a BMI of 27 or higher) who also have another condition such as high blood pressure, high cholesterol or type 2 diabetes. Each drug must be used in combination with a low-calorie diet and exercise plan.

But they work differently.

Belviq (lorcaserin) helps suppress appetite by activating a part of the brain called the serotonin 2C receptor. In clinical trials that lasted one to two years and included almost 8,000 people, those taking Belviq lost about 3% to 4% more weight, on average, than those taking a placebo.

Qsymia is a combination of an appetite suppressant (phentermine) and an antiseizure and migraine medication called topimirate. In studies that lasted up to one year and included nearly 3,700 people, those on Qsymia lost about 7% to 9% more weight, on average, than a placebo group.

Though neither drug was shown to harm the heart, neither is safe for pregnant women, and both have many potential side effects, including memory and attention problems, constipation, dry mouth and dizziness.


Should those who are eligible consider taking one of these drugs? If so, which is better?

“Qsymia is more effective than Belviq, but it’s also more toxic,” said David Katz, MD, MPH, founding director of the Yale University Prevention Research Center in Derby, Connecticut. “For example, the anti-epileptic drug in Qsymia acts directly on brain cells and is associated with suicidal thoughts.” So one isn’t clearly better than the other.

How do these two compare with the other approved prescription weight-loss drug that’s on the market, orlistat? Serious side effects also come into play with orlistat, said Dr. Katz, including anal leakage, but Belviq and Qysmia are generally more effective at reducing weight. Another advantage that the two new drugs have over orlistat is that they work best with a low-fat diet. Orlistat, on the other hand, doesn’t work well with a low-fat diet.

But all in all, Dr. Katz is not overly impressed by any of the drugs. “Their effects are modest, and many people will stop using them because of side effects,” he said.

Rather than prescribing drugs or performing surgery, teaching patients new lifestyle habits that help them consume fewer calories and exercise more is still the best solution, he added.

Dr. Katz would prescribe one of these drugs only rarely. “It depends on what you’ve tried before and what the stakes are of not fixing the problem,” he said. “Among certain patients, I might use one temporarily to pull them back from the brink and jump-start weight loss while teaching them life skills that can eventually take over.”

Neither new drug is available yet—Qsymia is expected on the market in late 2012 and Belviq in early 2013. Prices aren’t known. If you’re obese or overweight with a related health condition, ask your doctor whether one of these new drugs might help. But remember that neither is a panacea!