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Long-Term Effectiveness of the Anti-Obesity Medication Phentermine

LEAP is going to test one specific anti-obesity medication called phentermine to see how well it works in helping people get to a lower body weight and improve their health.

Trial Features

Double-Blinded Study

Both the participants and the researchers working with the participants will be blinded to the treatment assignment.


The LEAP trial will enroll 1,000 participants across 5 clinical sites, all in the United States.

2 Intervention Arms

You will be randomly assigned, like the flip of a coin, to take phentermine or an identical placebo. A placebo is just a fake pill that looks like the real thing but doesn't do anything. In addition to the study drug or placebo, all participants will receive the WW (formerly known as Weight Watchers) online program.

Treatment Centered

Obesity is a chronic disease that requires long-term treatment. We want to see how safe this medication is when used long term.


LEAP is currently recruiting, click to learn if you are eligible to join!

Participants get free access to the WW (formerly known as Weight Watchers) app, a free scale, and the potential for weight loss! 

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