While a variety of obesity drugs are in various stages of clinical trials, there is no single good place to find a list of all the trials taking place of weight-loss medications.

It also is important to understand how clinical trials work, particularly if it is a Phase III double-blind, placebo-controlled trial -- the final stage of the study process that hopefully leads to submission of the drug to the FDA for regulatory approval.

Even if you find that a hospital near you that is participating in one of these Phase III trials, and you are accepted as a participant, you may not receive the weight-loss drug at all -- but may receive a placebo!

We will publish news of new clinical trials as we learn of them. Here is how the clinical trial process works.

Phase I Clinical Trial. These generally are small, comparatively short tests involving fewer than 100 normal, healthy volunteers. The tests study a drug’s safety profile, including the safe dosage range. The studies also determine how a drug is absorbed, distributed, metabolized, and excreted as well as the duration of its action.

Phase II Clinical Trial. These are controlled trials generally involving somewhere between 100 to 500 volunteer patients (people with the disease) to assess a drug’s effectiveness.

Phase III Clinical Trial. These are the big, multicenter trials that are conducted to gather the information needed to apply for regulatory approval to sell the drug. They generally involve at least 1,000 and sometimes more than 10,000 patients (only half of whom generally get the drug, while the other half get a placebo). Physicians monitor patients closely to confirm efficacy and identify adverse events.

New Drug Application (NDA). Following the completion of all three phases of clinical trials, a company analyzes all of the data and files an application for approval to market the drug with the FDA and European regulators if the data successfully demonstrate both safety and effectiveness.

Phase IV Clinical Trial. For some medicines, the FDA requires additional trials (Phase IV) to evaluate long-term effects.

Here are some trials of obesity drugs currently underway:

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