A Better FIT! Use of Medication to Improve Weight Loss in Suboptimal Early Responders to Behavioral Treatment

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    Recruiting
  • participants needed
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Updated on 21 November 2025

Summary

A 28-week research study is being conducted that is designed to help all participants lose weight. All participants will receive lifestyle modification (diet, exercise, and behavioral treatment). Participants who do not lose weight with lifestyle modification alone also will be prescribed an FDA-approved weight loss medication (phentermine) or placebo.

Description

This study has several goals. They include examining individual characteristics that may predict weight loss with lifestyle modification. The study will also examine the effectiveness of phentermine in increasing weight loss for patients with slow early weight loss with lifestyle modification alone. 

All participants will receive the same lifestyle modification program of diet, physical activity, and behavior therapy, which is currently recommended as the first-line treatment for weight loss. After completing 4 weeks of this treatment, they will attend a progress assessment visit in which they will review their weight loss with the research team. 

Most participants (2 out of 3) are expected to successfully lose weight with lifestyle modification alone. Because early weight loss predicts later success, individuals whose weight loss is on target are not likely to need additional tools to help them to succeed. These individuals will continue to receive an additional 24 weeks of lifestyle modification to help them to achieve their goals. 

For the minority of participants who lose minimal weight with lifestyle modification, we will evaluate whether adding the weight loss medication phentermine helps them to achieve greater weight loss, as compared with being prescribed placebo. To do this, participants with slow early weight loss after 4 weeks of treatment will be randomly assigned to either phentermine or placebo in addition to continued participation in the lifestyle modification program for 24 more weeks. 



To see if you may be eligible for this study, please complete the prescreening questions below. You may be asked some personal health questions. You do not have to answer any questions you do not wish to answer, and you may stop at any time. Answering these questions is voluntary. This means that, no matter what you decide to do, your decision will not affect your relationship with or care provided by the University of Pennsylvania. 
 
The screening questions below do not send any information directly to the research team.  None of your answers will be saved by the research team. If you appear to meet criteria, you can choose to notify the research team of your interest in the study through the iConnect system or by phone. 

FAQ


Details
Condition obesity,weight,weight management,weight loss,weight loss medication,obesity pharmacotherapy,lifestyle modification,overweight, chronic back pain
Age 21years - 70years
Clinical Study IdentifierNCT03779048
Last Modified on21 November 2025

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Additional screening procedures may be conducted by the study team before you can be confirmed eligible to participate.

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If you are confirmed eligible after full screening, you will be required to understand and sign the informed consent if you decide to enroll in the study. Once enrolled you may be asked to make scheduled visits over a period of time.

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Complete your scheduled study participation activities and then you are done. You may receive summary of study results if provided by the sponsor.

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