Obesity & OverweightPhase 4NCT07870668
Intermittent Phentermine for Obesity and Body Composition
A Phase 4 study testing Phentermine 15 MG, Phentermine 30 mg and Phentermine 37.5 Mg in people with Obesity & Overweight, run by OSCAR MANUEL TORRES FALCON at 1 site in Mexico.
Trial summary
This study evaluated the effects of intermittent phentermine treatment on body fat, estimated visceral adiposity, body composition, and tolerability in adults with overweight or obesity. Read more about this study
- Who is it for?
- Ages 21 to 40 years
- Conditions the study is for
- Obesity & Overweight
- What is being tested?
- Phentermine 15 MG, Phentermine 30 mg and Phentermine 37.5 Mg
- Type of treatment
- Pill or oral medicine, Lifestyle or therapy programme
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 600 participants
- Where
- 1 siteMexico
- Study dates
- 1 Mar 2024to 15 Jan 2026
- Phase
- Phase 4
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 21 to 40 years
- All sexes
- No healthy volunteers
- Adult
Who may be able to join
- Age 21 to 40 years.
- Body mass index (BMI) 27 to 35 kg/m².
- Eligible for structured obesity treatment.
- Willingness to complete serial body-composition assessments.
Who cannot join
- Pregnancy or breastfeeding.
- Known contraindication to sympathomimetic therapy.
- Uncontrolled hypertension.
- Clinically significant cardiovascular disease.
- Medical or psychiatric conditions judged to make participation unsafe or compromise protocol adherence.
Trial locations and contacts
1 site in 1 country.
About this study
Official title: Adaptive Pharmacotherapy in Obesity: Intermittent Phentermine Improves Visceral Adiposity and Body Composition
This study evaluated the effects of intermittent phentermine treatment on body fat, estimated visceral adiposity, body composition, and tolerability in adults with overweight or obesity.
A total of 600 adults aged 21 to 40 years with a body mass index (BMI) between 27 and 35 kg/m² participated in a single-center, randomized, four-group clinical trial conducted at Hospital Médica Campestre in León, Guanajuato, Mexico.
Read more
Participants were assigned to lifestyle modification alone or lifestyle modification combined with phentermine at doses of 15 mg, 30 mg, or 37.5 mg daily. Phentermine was administered intermittently using a schedule of three months of treatment followed by one month without medication during a 14-month observation period.
All participants received nutritional guidance and physical activity recommendations. Body composition was assessed using bioelectrical impedance analysis and three-dimensional body scanning.
The primary outcome was the relative percentage reduction in total body fat from baseline to Month 14. Secondary outcomes included estimated visceral adiposity, waist circumference, lean body mass, body weight, BMI, medication adherence, resting heart rate, blood pressure, treatment-emergent adverse events, and treatment discontinuation.
The study aimed to evaluate the dose-response effects of intermittent phentermine on body composition and the balance between efficacy and tolerability.
Read the detailed description
This investigator-initiated, single-site, randomized, parallel-group clinical trial evaluated the efficacy and tolerability of intermittent, dose-stratified phentermine therapy combined with structured lifestyle modification.
A total of 600 adults aged 21-40 years with BMI values between 27 and 35 kg/m² were randomized in a 1:1:1:1 ratio to four groups: lifestyle-only control, phentermine 15 mg, phentermine 30 mg, or phentermine 37.5 mg, with 150 participants per group.
All participants received a structured lifestyle intervention targeting an approximate daily energy deficit of 500 kcal and 150 minutes of aerobic physical activity per week. Participants assigned to pharmacological treatment received oral phentermine hydrochloride once daily during active treatment periods. The intermittent treatment schedule consisted of three consecutive months of medication followed by one month without medication during the 14-month observation period.
Body composition was evaluated using multifrequency bioelectrical impedance analysis and three-dimensional optical body scanning. Assessments included total body fat, estimated visceral adiposity, waist circumference, lean body mass, body weight, and BMI.
The primary endpoint was the relative percentage reduction in total body fat from baseline to Month 14. Secondary endpoints included relative percentage reduction in estimated visceral adiposity, absolute change in waist circumference, change in lean body mass, body weight, BMI, medication adherence, resting heart rate, blood pressure, treatment-emergent adverse events, and treatment discontinuation.
The intervention was open label for participants and treating clinicians, while body-composition assessors and the primary statistical analyst were blinded to treatment allocation.
The study was conducted at Hospital Médica Campestre in León, Guanajuato, Mexico, under protocol 1-0029, approved by the Hospital Médica Campestre Ethics Committee.
- Conditions
- Obesity & Overweight
- Being tested
- Phentermine 15 MG, Phentermine 30 mg, Phentermine 37.5 Mg, Lifestyle Management
- Keywords
- Phentermine, Obesity, Visceral Adiposity, Body Composition, Intermittent Pharmacotherapy, Dose-Response Relationship, Fat Mass Reduction, Bioelectrical Impedance Analysis, 3D Body Scanning, Overweight
- Medical subject headings
- Obesity, Overweight
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Phentermine 15 MGDrug
Oral phentermine hydrochloride 15 mg administered once daily during active-treatment periods using a planned intermittent schedule of 3 months on treatment followed by 1 month off treatment, repeated over the 14-month observation period, in combination with structured lifestyle treatment.
Phentermine 30 mgDrug
Oral phentermine hydrochloride 30 mg administered once daily during active-treatment periods using a planned intermittent schedule of 3 months on treatment followed by 1 month off treatment, repeated over the 14-month observation period, in combination with structured lifestyle treatment.
Phentermine 37.5 MgDrug
Oral phentermine hydrochloride 37.5 mg administered once daily during active-treatment periods using a planned intermittent schedule of 3 months on treatment followed by 1 month off treatment, repeated over the 14-month observation period, in combination with structured lifestyle treatment.
Lifestyle ManagementBehavioural
Structured lifestyle treatment targeting an energy deficit of approximately 500 kcal/day and approximately 150 minutes/week of aerobic physical activity.
| Study group | Role | What they receive |
|---|---|---|
| Lifestyle Intervention (control) | Active comparator | Participants received structured lifestyle treatment targeting an energy deficit of approximately 500 kcal/day and approximately 150 minutes/week of aerobic physical activity, without phentermine administration. Receives: Behavioral: Lifestyle Management |
| Phentermine 15 mg | Experimental | Participants received oral phentermine hydrochloride 15 mg once daily during active-treatment periods using a planned intermittent schedule of 3 months on treatment followed by 1 month off treatment, repeated over the 14-month observation period, in combination with structured lifestyle treatment. Receives: Drug: Phentermine 15 MG; Behavioral: Lifestyle Management |
| Phentermine 30 mg | Experimental | Participants received oral phentermine hydrochloride 30 mg once daily during active-treatment periods using a planned intermittent schedule of 3 months on treatment followed by 1 month off treatment, repeated over the 14-month observation period, in combination with structured lifestyle treatment. Receives: Drug: Phentermine 30 mg; Behavioral: Lifestyle Management |
| Phentermine 37.5 mg | Experimental | Participants received oral phentermine hydrochloride 37.5 mg once daily during active-treatment periods using a planned intermittent schedule of 3 months on treatment followed by 1 month off treatment, repeated over the 14-month observation period, in combination with structured lifestyle treatment. Receives: Drug: Phentermine 37.5 Mg; Behavioral: Lifestyle Management |
What is being measured
The primary outcome is the main question the study is designed to answer.
Relative Percentage Reduction in Total Body Fat from Baseline
Relative percentage reduction in total body fat from baseline to Month 14, calculated as 100 × (baseline value - Month 14 value) / baseline value.
Measured: Baseline through Month 14
Secondary outcomes (10)
Relative Percentage Reduction in Estimated Visceral Adiposity from Baseline
Relative percentage reduction in estimated visceral adiposity from baseline to Month 14, calculated as 100 × (baseline value - Month 14 value) / baseline value. Visceral adiposity was estimated using the study body-composition assessment protocol and was not directly measured by CT or MRI.
Measured: Baseline and 14 months
Change in Lean Body Mass from Baseline
Change in estimated lean mass from baseline, assessed using bioelectrical impedance analysis to compare changes among the lifestyle control group and the three intermittent phentermine dose groups.
Measured: Baseline and 14 months
Change in Body Weight from Baseline
Change in body weight from baseline, expressed as absolute weight change and percentage of initial body weight, comparing the lifestyle control group with the three intermittent phentermine dose groups.
Measured: Baseline and 14 months
Treatment-Emergent Adverse Events.
Number and percentage of participants experiencing treatment-emergent adverse events during the study. Adverse events were assessed at scheduled visits and by spontaneous reporting and were classified according to severity and relationship to treatment.
Measured: Baseline through Month 14
Waist Circumference
Absolute change in waist circumference from baseline to Month 14, measured in centimeters.
Measured: Baseline to Month 14
Change in Body Mass Index from Baseline
Change in body mass index (BMI) from baseline to Month 14, calculated as body weight in kilograms divided by height in meters squared (kg/m²).
Measured: Baseline to Month 14
Medication Adherence
Medication adherence during the study, assessed from planned medication exposure, medication accountability, and scheduled follow-up visits.
Measured: Baseline through Month 14
Resting Heart Rate
Change in resting heart rate from baseline through Month 14, measured in beats per minute during scheduled study visits.
Measured: Baseline through Month 14
Blood Pressure
Change in systolic and diastolic blood pressure from baseline through Month 14, assessed during scheduled study visits.
Measured: Baseline through Month 14
Treatment Discontinuation
Number and percentage of participants who discontinued treatment during the study, including discontinuations related to adverse events.
Measured: Baseline through Month 14
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted13 Oct 2026
- Study start1 Mar 2024
- Primary completion15 Jan 2026
- Study completion15 Jan 2026
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Obesity & OverweightStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 4
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Model description
- Four-arm, parallel-group randomized clinical trial comparing structured lifestyle treatment alone with three intermittent phentermine dosing regimens (15 mg, 30 mg, and 37.5 mg) combined with lifestyle treatment. Participants were randomized 1:1:1:1 to one study arm and followed a 3-month-on/1-month-off treatment schedule over 14 months. Total body fat, estimated visceral adiposity, body composition, and treatment tolerability were evaluated
- Masking
- Single blind
- Who is masked
- Outcomes assessor
- Enrolment
- 600 participants (actual)
Sponsor and investigators
- Lead sponsor
- OSCAR MANUEL TORRES FALCON
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor-investigator, OSCAR MANUEL TORRES FALCON, Hospital Médica Campestre
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07870668
- Sponsor's protocol ID
- 1-0029
- Status last verified
- Oct 2026
- First submitted
- 6 Oct 2026
- Last updated
- 13 Oct 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Yes: Deidentified individual participant-level data underlying the reported results, together with a data dictionary, may be shared with qualified researchers after publication.
Study at a glance
From the registry record, last updated by the sponsor on 13 Oct 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Adaptive Pharmacotherapy in Obesity: Intermittent Phentermine Improves Visceral Adiposity and Body Composition
- ClinicalTrials.gov ID
- NCT07870668
- Acronym / sponsor ID
- 1-0029
- Conditions
- Obesity & Overweight
- Keywords
- Phentermine, Obesity, Visceral Adiposity, Body Composition, Intermittent Pharmacotherapy, Dose-Response Relationship, Fat Mass Reduction, Bioelectrical Impedance Analysis
- Phase
- Phase 4
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 600 participants (actual)
- Lead sponsor
- OSCAR MANUEL TORRES FALCONUniversity, hospital or other
- Study start
- 1 Mar 2024 (actual)
- Primary completion
- 15 Jan 2026 (actual)
- Study completion
- 15 Jan 2026 (actual)
- First posted
- 13 Oct 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
This study evaluated the effects of intermittent phentermine treatment on body fat, estimated visceral adiposity, body composition, and tolerability in adults with overweight or obesity.
A total of 600 adults aged 21 to 40 years with a body mass index (BMI) between 27 and 35 kg/m² participated in a single-center, randomized, four-group clinical trial conducted at Hospital Médica Campestre in León, Guanajuato, Mexico.
Participants were assigned to lifestyle modification alone or lifestyle modification combined with phentermine at doses of 15 mg, 30 mg, or 37.5 mg daily. Phentermine was administered intermittently using a schedule of three months of treatment followed by one month without medication during a 14-month observation period.
All participants received nutritional guidance and physical activity recommendations. Body composition was assessed using bioelectrical impedance analysis and three-dimensional body scanning.
The primary outcome was the relative percentage reduction in total body fat from baseline to Month 14. Secondary outcomes included estimated visceral adiposity, waist circumference, lean body mass, body weight, BMI, medication adherence, resting heart rate, blood pressure, treatment-emergent adverse events, and treatment discontinuation.
The study aimed to evaluate the dose-response effects of intermittent phentermine on body composition and the balance between efficacy and tolerability.
Detailed description
This investigator-initiated, single-site, randomized, parallel-group clinical trial evaluated the efficacy and tolerability of intermittent, dose-stratified phentermine therapy combined with structured lifestyle modification.
A total of 600 adults aged 21-40 years with BMI values between 27 and 35 kg/m² were randomized in a 1:1:1:1 ratio to four groups: lifestyle-only control, phentermine 15 mg, phentermine 30 mg, or phentermine 37.5 mg, with 150 participants per group.
All participants received a structured lifestyle intervention targeting an approximate daily energy deficit of 500 kcal and 150 minutes of aerobic physical activity per week. Participants assigned to pharmacological treatment received oral phentermine hydrochloride once daily during active treatment periods. The intermittent treatment schedule consisted of three consecutive months of medication followed by one month without medication during the 14-month observation period.
Body composition was evaluated using multifrequency bioelectrical impedance analysis and three-dimensional optical body scanning. Assessments included total body fat, estimated visceral adiposity, waist circumference, lean body mass, body weight, and BMI.
The primary endpoint was the relative percentage reduction in total body fat from baseline to Month 14. Secondary endpoints included relative percentage reduction in estimated visceral adiposity, absolute change in waist circumference, change in lean body mass, body weight, BMI, medication adherence, resting heart rate, blood pressure, treatment-emergent adverse events, and treatment discontinuation.
The intervention was open label for participants and treating clinicians, while body-composition assessors and the primary statistical analyst were blinded to treatment allocation.
The study was conducted at Hospital Médica Campestre in León, Guanajuato, Mexico, under protocol 1-0029, approved by the Hospital Médica Campestre Ethics Committee.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Single blind (outcomes assessor)
- Number of arms
- 4
- Model description
- Four-arm, parallel-group randomized clinical trial comparing structured lifestyle treatment alone with three intermittent phentermine dosing regimens (15 mg, 30 mg, and 37.5 mg) combined with lifestyle treatment. Participants were randomized 1:1:1:1 to one study arm and followed a 3-month-on/1-month-off treatment schedule over 14 months. Total body fat, estimated visceral adiposity, body composition, and treatment tolerability were evaluated
| Arm | Type | Receives |
|---|---|---|
| Lifestyle Intervention (control) | Active comparator | Behavioral: Lifestyle ManagementParticipants received structured lifestyle treatment targeting an energy deficit of approximately 500 kcal/day and approximately 150 minutes/week of aerobic physical activity, without phentermine administration. |
| Phentermine 15 mg | Experimental | Drug: Phentermine 15 MG, Behavioral: Lifestyle ManagementParticipants received oral phentermine hydrochloride 15 mg once daily during active-treatment periods using a planned intermittent schedule of 3 months on treatment followed by 1 month off treatment, repeated over the 14-month observation period, in combination with structured lifestyle treatment. |
| Phentermine 30 mg | Experimental | Drug: Phentermine 30 mg, Behavioral: Lifestyle ManagementParticipants received oral phentermine hydrochloride 30 mg once daily during active-treatment periods using a planned intermittent schedule of 3 months on treatment followed by 1 month off treatment, repeated over the 14-month observation period, in combination with structured lifestyle treatment. |
| Phentermine 37.5 mg | Experimental | Drug: Phentermine 37.5 Mg, Behavioral: Lifestyle ManagementParticipants received oral phentermine hydrochloride 37.5 mg once daily during active-treatment periods using a planned intermittent schedule of 3 months on treatment followed by 1 month off treatment, repeated over the 14-month observation period, in combination with structured lifestyle treatment. |
Who may qualify
- Ages
- 21 to 40 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult
Key inclusion criteria (4 listed)
- Age 21 to 40 years.
- Body mass index (BMI) 27 to 35 kg/m².
- Eligible for structured obesity treatment.
- Willingness to complete serial body-composition assessments.
Key exclusion criteria (5 listed)
- Pregnancy or breastfeeding.
- Known contraindication to sympathomimetic therapy.
- Uncontrolled hypertension.
- Clinically significant cardiovascular disease.
- Medical or psychiatric conditions judged to make participation unsafe or compromise protocol adherence.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Phentermine 15 MGOral phentermine hydrochloride 15 mg administered once daily during active-treatment periods using a planned intermittent schedule of 3 months on treatment followed by 1 month off treatment, repeated over the 14-month observation period, in combination with structured lifestyle treatment. | Drug | Phentermine 15 mg |
| Phentermine 30 mgOral phentermine hydrochloride 30 mg administered once daily during active-treatment periods using a planned intermittent schedule of 3 months on treatment followed by 1 month off treatment, repeated over the 14-month observation period, in combination with structured lifestyle treatment. | Drug | Phentermine 30 mg |
| Phentermine 37.5 MgOral phentermine hydrochloride 37.5 mg administered once daily during active-treatment periods using a planned intermittent schedule of 3 months on treatment followed by 1 month off treatment, repeated over the 14-month observation period, in combination with structured lifestyle treatment. | Drug | Phentermine 37.5 mg |
| Lifestyle ManagementStructured lifestyle treatment targeting an energy deficit of approximately 500 kcal/day and approximately 150 minutes/week of aerobic physical activity. | Behavioural | Lifestyle Intervention (control), Phentermine 15 mg, Phentermine 30 mg, Phentermine 37.5 mg |
Primary outcome
Relative Percentage Reduction in Total Body Fat from Baseline
Time frame: Baseline through Month 14
Relative percentage reduction in total body fat from baseline to Month 14, calculated as 100 × (baseline value - Month 14 value) / baseline value.
10 secondary outcomes
Relative Percentage Reduction in Estimated Visceral Adiposity from Baseline
Time frame: Baseline and 14 months
Change in Lean Body Mass from Baseline
Time frame: Baseline and 14 months
Change in Body Weight from Baseline
Time frame: Baseline and 14 months
Treatment-Emergent Adverse Events.
Time frame: Baseline through Month 14
Waist Circumference
Time frame: Baseline to Month 14
Change in Body Mass Index from Baseline
Time frame: Baseline to Month 14
Medication Adherence
Time frame: Baseline through Month 14
Resting Heart Rate
Time frame: Baseline through Month 14
Blood Pressure
Time frame: Baseline through Month 14
Treatment Discontinuation
Time frame: Baseline through Month 14
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 13 Oct 2026.
- Individual participant dataSharing planned: Yes. Deidentified individual participant-level data underlying the reported results, together with a data dictionary, may be shared with qualified researchers after publication.
Related trials for Obesity & Overweight
RecruitingObservational study
Endoscopic Sleeve Gastroplasty (ESG) Prospective Trial for Obesity (EGO-Trial)
Obesity
Active, not recruitingPhase 4
Effects of Sequential Therapy With Mexidol® (Intravenous) and Mexidol® FORTE 250 (Oral) on Functional Brain Activity Assessed by Functional Magnetic Resonance Imaging and Biochemical Parameters in Patients With Chronic Cerebral Ischemia: A Comparison of Patients With and Without Metabolic Disorders
Metabolic Abnormalities, Obesity & Overweight
Recruiting
Exercise Training and Vitamin D Metabolism
Obesity & Overweight, Vitamin D
Recruiting
Metabolic Health, Bones and Nuts During Weight Loss in Adults
Weight Loss, Bone Density
Active, not recruiting
Effect of Probiotics on Insulin Sensitivity in Overweight and Obese Pregnancy
Obesity & Overweight, Gestational Diabetes Mellitus (GDM)
Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
The record lists no contact. Use the official record to reach the sponsor.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 4 study testing Phentermine 15 MG, Phentermine 30 mg and Phentermine 37.5 Mg in people with Obesity & Overweight, run by OSCAR MANUEL TORRES FALCON at 1 site in Mexico.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 4 inclusion and 5 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 13 Oct 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Mexico. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this phase mean?
Phase 4 studies take place after a treatment is approved, to learn more about its long-term benefits and risks in everyday use.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Relative Percentage Reduction in Total Body Fat from Baseline (time frame: Baseline through Month 14). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 13 Oct 2026.