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For the past 20 years, as Americans steadily gained weight, experts have searched for ways to reverse the trend. The reasons we gain and lose are complicated, they've learned, and involve more than just diet and exercise.
Drugs can help, of course. Two are currently approved for long-term use: Meridia works in the brain to suppress appetite; Xenical blocks the absorption of fat -- with unpleasant gastrointestinal side effects for some. And there's surgery, which is increasingly done laparoscopically but still has risks. We're all hoping, though, for a magic bullet. Biotech and pharma companies are spending millions to develop more powerful pills, gadgets and procedures to put an end to the condition that can trigger a host of serious diseases -- obesity.
This quest isn't easy. "We're finding that many behaviors we don't think of as genetic often have a genetic basis," says Susan Yanovski, MD, an obesity expert at the National Institute of Diabetes and Digestive and Kidney Diseases. "Some people get hungrier sooner than others; some fill up less quickly." Some binge; others are emotional eaters. And as more research is done, specific treatments may be discovered to deal with the various causes of obesity.
"The future is really bright for the development of better, safer and effective drugs," says Dr. Yanovski. "We're going to have more choices to treat obesity. And they'll be more specific, so you can target the medication to the patient, as we do in the treatment of high blood pressure." Here, some of the most exciting advances.
Ask doctors what their biggest hope is for the near future and many will home in on rimonabant. Sanofi-Aventis, the pill's maker, is awaiting FDA approval; the drug is already available in Europe. Rimonabant stifles hunger and cravings by targeting the endocannabinoid system, which plays a role in regulating weight. Cannabinoid receptors throughout the body are thought to stimulate cravings; rimonabant blocks the receptors, knocking out cravings. It also lowers triglycerides and improves HDL cholesterol.
Experts are excited about the drug, but agree it won't be a cure-all. "You can eat your way through rimonabant -- and all obesity treatments," says Mehmet C. Oz, MD, director of the Cardiovascular Institute at Columbia University Medical Center in New York City and co-author of You: On a Diet. On the other hand, one study found that following a healthy diet and exercising, in conjunction with obesity drugs, made them more effective.
Plus, you can't just take a pill, lose the weight and stop. "You've got to take obesity medications for a long time, if not for life," says Samuel Klein, MD, director of the Center for Human Nutrition at Washington University School of Medicine in St. Louis. "You don't lower your blood pressure with medication and then say, 'Okay, now I'm going to stop.' If you lose weight and stop the treatment, it will bounce right back up again. That's been proved over and over again."
In any case, obesity drugs are reserved for people with a body mass index (BMI) of 30 and above, or a BMI of 27 or higher with diabetes, high blood pressure or another complication of obesity. They're not for the "gotta lose those last ten pounds" dieter. And a review of studies found that rimonabant usually only leads to an 11-pound weight loss a year on average.
The Obesity Vaccine
Rimonabant is one of dozens of drugs being studied. But medications that target the stomach may also be helpful, says Dr. Oz. "I think the best drugs will be those that work on the hormones in the gut. By the time you're working on the brain, it's a little bit late. The stimulus is already coming from the gut. The best way to influence hunger is to influence the gut's signal to the brain to eat," he says. "That way, you affect all the chemicals in the brain the way they're supposed to be affected."
To that end, researchers are looking at a hormone called ghrelin, scourge of yo-yo dieters. When you diet, your body goes into survival mode and ramps up ghrelin production, which may slow your metabolism, encourage eating and force your body to retain fat.
A team of scientists at the Scripps Research Institute have found that keeping ghrelin from reaching the brain may prevent weight gain. When they injected rats with the so-called obesity vaccine, the rats ate normally but gained less weight and had less body fat than rats that didn't get the vaccine. Of course, the rats weren't on our high-fat, high-calorie diet.
The vaccine is far from being tested on humans, but it would be intended for the seriously overweight, and might have to be taken for life, says Kim Janda, PhD, one of the researchers who developed it.
Drugs are promising, but still, regulating your food intake is complicated, says Dr. Klein, since there are so many pathways involved. And even when the pathways are working, and you eat enough to feel satisfied (not stuffed), there are environmental triggers like the aroma of fresh-baked cookies that may lead you to eat though you're not hungry. "Ultimately, it may take multiple drugs blocking multiple pathways to work," he says.
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