Should you take one of the new weight loss drugs?

Qsymia is one of the new anti-obesity drugs approved by the FDA. (AP Photo/Vivus Pharmaceuticals Inc.)
Qsymia is one of the new anti-obesity drugs approved by the FDA. (AP Photo/Vivus Pharmaceuticals Inc.)

The approval this week of a new weight loss pill called Qsymia means that doctors will soon be able to prescribe two new drugs to help overweight people shed pounds. Last month, the US Food and Drug Administration approved the pill Belviq, the first drug approved for obesity in 13 years. Both drugs will hit pharmacies later this year and their cost, yet to be determined, will probably be about $100 to $200 a month.

I asked Dr. Richard Siegel, co-director of the Diabetes Center at Tufts Medical Center, to sort out the pros and cons of these new medications and who might be appropriate candidates for drug therapy. Here are edited excerpts from our interview.

Which people are most likely to benefit from these drugs?

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Both drugs were approved for those who are obese—defined as a body mass index of 30 or above—or overweight with a BMI of at least 27 and a weight-related complication such as diabetes, high blood pressure, or high cholesterol. (Note: A 5’5” person who is 163 pounds has a BMI of 27, and at 180 pounds has a BMI of 30.)

How much weight can people expect to lose?

It’s variable but the clinical trials performed by the drug manufacturers found that Belviq leads to an average drop in body weight of about 5 percent, while Qsymia leads to an average decline of 10 percent. I tell patients that the more effort they put into it, the more results they can get from weight-loss drugs. Yes, they can lose a few pounds if they just take a pill and do nothing else, but if they join a support group, meet with a nutritionist to map out a new eating plan, and start exercising, they might exceed those average weight losses seen in study participants.

I saw a woman recently who dropped 15 percent of her body weight and had been taking phentermine (an older obesity drug) intermittently over the past few years; I told her it was her switch to a vegetable- and fish-rich diet, not the pills, that primarily led to her weight loss.

What side effects are associated with these new drugs?

Belviq (lorcaserin hydrochloride) has been associated with attention and memory problems, according to the FDA, and may cause low blood sugar in diabetics. Qsymia (a combination of phentermine and another older drug, the anticonvulsant topirimate) can increase a patient’s heart rate, and the FDA said it is not known whether this has any detrimental effect on those at high risk of having a heart attack and stroke. Qsymia can also cause tingling in the hands and feet and shouldn’t be taken during pregnancy because it increases the risk of birth defects.

Both drugs, like many others, can cause headaches, dizziness, fatigue, and nausea, and the FDA is requiring both manufacturers to conduct longer-term studies to assess heart and stroke risks.

How long can people safely stay on these drugs, and will they gain the weight back once they go off?

I think patients need to be on a short leash with any weight-loss drug. I write prescriptions for no more than three months at a time and will likely do so for these new drugs. Patients need to come in for frequent followup visits to see whether the medication is working and whether they’re tolerating the drug well.

We don’t really know much about the safety beyond two years of use, so I wouldn’t feel comfortable keeping anyone on any drug beyond that time. We also don’t know the full extent of weight regain after patients stop taking the pills, but trials indicate some regain of the lost weight.

Do you have any concerns that healthy folks who are 15 or 20 pounds overweight will be using these drugs for a quick fix?

I think after the disaster with fen-phen (the drug combination fenfluramine/phentermine that was removed from the market after it was linked to heart valve problems), many primary care physicians have been reluctant to prescribe obesity drugs if there’s any question about whether a patient is a good candidate. Instead, they’ll refer these patients to clinics like mine.

I often tell such patients that anti-obesity drugs weren’t tested in those who were moderately overweight, so we have no way of knowing how effective they are in that population. And the risks of side effects from the drugs wouldn’t make those small weight-loss benefits worthwhile. A better approach would be lifestyle modifications such as increased exercise and a diet overhaul.

We also need to look at the ultimate endpoint, which is disease reduction. A small amount of weight loss can really improve the health of someone who’s obese or already has diabetes but might have little, if any, benefit for someone who’s already in good health.

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