(MCT)-- Weight-loss drugs have so far been a complete bust. But they may be verging on a comeback, now that the Food and Drug Administration has approved two new prescription diet pills for the first time in more than a decade.
Both weight-loss medications failed to get federal approval in 2010 because of safety concerns, including heart risks and birth defects. After the drug companies submitted additional safety data, however, the agency OK'd the applications.
Critics argue that weight-loss drugs don't have enough benefits to justify the risk. But resources aimed at improving diet and increasing physical activity have not been helping the nearly 1 in 3 Americans dealing with extreme weight gain.
Obesity continues to be "one of the most significant public health challenges facing the United States," according to a report issued by the George Washington University School of Public Health and Health Services.
The drugs are meant for overweight and obese adults with a body mass index (BMI) greater than 30 or for those who have a weight-related condition, such as high blood pressure, elevated cholesterol or Type 2 diabetes, and a BMI over 27. Pregnant women shouldn't touch these drugs. And "they should never be taken for cosmetic purposes," said Dr. Donna Ryan, professor emeritus at Pennington Biomedical Research Center and a consultant to drug companies.
But do they work? Are they safe? Here's the skinny:
How it works: Belviq, or lorcaserin, activates a serotonin receptor in the brain that may help a person eat less and feel full after eating smaller amounts of food. In clinical trials, patients on average lost just 5 percent of body weight after taking the drug for a year along with eating less and exercising more.
Concerns: The drug could potentially damage heart valves. Fenfluramine, a similar serotonin-based weight-loss drug, was taken off the market in 1997 due to the same heart concerns. Belviq shows "an increased incidence of adverse reactions related to cognition and mood," according to the FDA. Still unknown: the long-term risk of heart attack and stroke, and the safety and efficacy when used with other diet medications. The most common side effects are headache, dizziness, fatigue, nausea, dry mouth and constipation.
How it works: Qsymia is a combination of two FDA-approved drugs, phentermine and an extended-release form of topiramate. Phentermine increases levels of norepinephrine, a neurotransmitter in the part of the brain that controls appetite. This reduces hunger and increases satiety. Topiramate, an anticonvulsant used to prevent migraine headaches, is thought to affect another neurotransmitter. But it's not known how it reduces food intake, Ryan said. Approximately 62 percent of patients who took the recommended dose for a year, and dieted and exercised, lost at least 5 percent of their body weight, according to two trials.