The L-Marc Research Center (Louisville Metabolic and Atheroscerosis Research Center) in Louisville, Kentucky, is one of the most active metabolic research centers in the world, focusing on Phase II-IV clinical trials of weight-loss drugs.

The clinic is a leading recruiter of participants in weight-loss trials, and when it runs ads for volunteers in the local newspapers, far more obese and overweight individuals than needed eagerly apply.

"I've had people crying on the phone," Heather Hausberger, the dietitian who screens applicants, recently told the New York Times. "They've tried everything. Nothing seems to work. A lot of people are looking for the quick fix, the magic pill."

Many drug makers, from pharmaceutical giants to tiny companies, are also spending billions of dollars in search of the "magic pill." MedMark Diligence, a research firm, estimates than as many as 200 drug candidates are either in early stages of research or being tested in clinical trials.

The most eagerly awaited "magic pill" at the moment is Acomplia (rimonabant), whose developer, Sanofi-Aventis, has now reported two years of clinical trial data suggesting that Acomplia not only helps overweight individuals shed pounds and keep the weight off, but also helps reduce risk factors linked to diabetes and heart disease.

Acomplia was not one of the drugs involved in the clinical trials conducted at the L-Mark Research Center.

Acomplia is expected to be submitted to the U.S. Food and Drug Administration and European regulatory authorities for marketing approval in the next two months.

When approved, it is expected to quickly overtake the current number-one prescription weight-loss medication, Xenical, which had worldwide sales of just under $500 million last year but has not been the "magic pill" patients were hoping for.

Some patients have been deterred by the fact that the medicine -- which works by hindering the body's ability to absorb fat -- can cause diarrhea when people eat a high-fat meal.

GlaxoSmithKline hopes that a non-prescription 60 mg dose of the drug under development -- half the strength of the current mg prescription version -- may produce fewer adverse side effects.