ObesityMETPROSNCT06340321
Impact of Metabolic Flexibility on Changes in Metabolic Health
An observational study of Obesity and Metabolic Syndrome, run by Pennington Biomedical Research Center at 1 site in United States.
Trial summary
Metabolic flexibility is the capacity to adapt fuel oxidation to fuel availability so that ATP synthesis can match its cellular demands. Thus, for example, increases in glucose availability after a meal would increase glucose oxidation, while increases in lipid availability during fasting would increase lipid… Read more about this study
- Who is it for?
- Ages 20 to 65 yearsHealthy volunteers can take part
- Conditions the study is for
- Obesity, Metabolic Syndrome
- What is being tested?
- Metabolic flexibility in the fasted state, Metabolic flexibility in euglycemic-hyperinsulinemic clamp and Metabolic flexibility in the metabolic chamber
- How many people
- 18 participants
- Where
- 1 siteUnited States
- Study dates
- 9 Oct 2024to 27 Aug 2025
- Phase
- Observational
- 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 20 to 65 years
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Study population: Individuals who participated in the InSight study at Pennington Biomedical in 2008-2009. Such study enrolled healthy men and women aged 20-36 years, with a body mass index <27.5 kg/m2, and a fasting glycemia <126 mg/dL.
Who may be able to join
- Individuals who participated in the InSight study at Pennington Biomedical in 2008-2009.
Who cannot join
- Women who are currently pregnant or breastfeeding, have been pregnant in the last 12 months, and/or were breastfeeding in the last 6 months.
Trial locations and contacts
1 site in 1 country.
United States1 site
Pennington Biomedical Research Center
Baton Rouge, Louisiana, 70808
About this study
Metabolic flexibility is the capacity to adapt fuel oxidation to fuel availability so that ATP synthesis can match its cellular demands. Thus, for example, increases in glucose availability after a meal would increase glucose oxidation, while increases in lipid availability during fasting would increase lipid oxidation. Enhanced metabolic flexibility has been proposed to protect humans from metabolic diseases. Nevertheless, most studies examining associations between metabolic flexibility and metabolic health outcomes have used cross-sectional designs. Whether impaired metabolic flexibility causes or results from metabolic health impairment is thus unclear.
In this study, the investigators will use the data from a study conducted approximately 16 years ago in healthy participants without obesity. Using the data already collected in that study, the metabolic flexibility of each participant will be calculated. To test the association between metabolic flexibility and the change in metabolic health, the investigators will call back all the participants for a single follow-up visit to reassess several metabolic health outcomes. Thus, the main aim of the study is to test the association between metabolic flexibility and the change in metabolic health outcomes after 16 years in humans.
Read the detailed description
Metabolic flexibility is the capacity to adapt fuel oxidation to fuel availability so that ATP synthesis can match its cellular demands. Thus, for example, increases in glucose availability after a meal would increase glucose oxidation, while increases in lipid availability during fasting would increase lipid oxidation. Enhanced metabolic flexibility has been proposed to protect humans from ectopic lipid accumulation and the subsequent development of insulin resistance and metabolic syndrome.
In humans, metabolic flexibility is assessed by measuring relative macronutrient oxidation (i.e., lipids and carbohydrates) in response to metabolic challenges that increase glucose or lipid availability. The respiratory exchange ratio (RER = CO2 production / O2 consumption) is used to determine relative macronutrient oxidation. The euglycemic-hyperinsulinemic clamp is a widely used challenge to assess metabolic flexibility as it increases glucose availability and thus relative glucose oxidation. Recently, other methods have been proposed to assess metabolic flexibility, including the relative lipid oxidation during an overnight fast or the difference between 24-hour RER and sleeping RER in non-exercise, energy balance conditions while staying in a metabolic chamber. The method most relevant for assessing the influence of metabolic flexibility and its effects on metabolic health outcomes is unknown.
The influence of metabolic flexibility on metabolic health outcomes remains uncertain. The lack of agreement across studies is explained by the variability in the metabolic challenges, differences in the analytical approach to compute metabolic flexibility, and the loose use of the metabolic flexibility concept in the context of many different phenomena. Moreover, most studies examining associations between metabolic flexibility and metabolic health outcomes have used cross-sectional designs. Whether impaired metabolic flexibility causes or results from metabolic health impairment is thus unclear. Longitudinal studies using well-controlled methods are required to determine the impact of metabolic flexibility on prospective metabolic health.
In this pilot and feasibility study, the investigators will use the data from a study conducted 16 years ago in 88 healthy participants without obesity (InSight study at Pennington Biomedical). The study included an euglycemic-hyperinsulinemic clamp, an overnight fasting assessment, a 24-hour stay in a metabolic chamber, and the measurement of metabolic health outcomes. Using the data already collected in the InSight study, the metabolic flexibility of each participant in the euglycemic-hyperinsulinemic clamp, the overnight fast, and the metabolic chamber will be calculated. To test the association between metabolic flexibility(ies) and the change in metabolic health outcomes, the investigators will call back all the participants for a single follow-up visit to reassess the metabolic health outcomes including body mass index, body composition, blood pressure, HOMA-IR, and the circulating concentrations of glucose, triglycerides, and cholesterol. Such data will shed light on the most informative method to assess metabolic flexibility in relationship to specific metabolic health outcomes. The investigators will use these preliminary data to design and power future projects to be submitted for funding to scientific federal agencies.
Our specific aims are to:
- Test the association between metabolic flexibility in response to a euglycemic-hyperinsulinemic clamp and the change in metabolic health outcomes after 16 years in humans.
- Test the association between metabolic flexibility in response to overnight fasting and the change in metabolic health outcomes after 16 years in humans.
- Test the association between metabolic flexibility in response to a 24-hour stay in a metabolic chamber and the change in metabolic health outcomes after 16 years in humans.
- Conditions
- Obesity, Metabolic Syndrome
- Being tested
- Metabolic flexibility in the fasted state, Metabolic flexibility in euglycemic-hyperinsulinemic clamp, Metabolic flexibility in the metabolic chamber
- Medical subject headings
- Obesity, Metabolic Syndrome
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Metabolic flexibility in the fasted stateDiagnostic test
Measured at baseline during the InSight study (2008-2009). Calculated as the respiratory exchange ratio in the fasting state adjusted for the circulating concentrations of free fatty acids
Metabolic flexibility in euglycemic-hyperinsulinemic clampOther
Measured at baseline during the InSight study (2008-2009). Calculated as the change in respiratory exchange ratio adjusted for glucose disposal rate
Metabolic flexibility in the metabolic chamberOther
Measured at baseline during the InSight study (2008-2009). Calculated as the difference between awake respiratory exchange ratio (from 8 a.m. to 11 p.m.) and sleeping respiratory exchange ratio during a 23-hour stay in the metabolic chamber
| Study group | Role | What they receive |
|---|---|---|
| Insight study cohort | The proposed study will include the individuals who participated in the baseline assessment of the InSight study at Pennington Biomedical in 2008-2009. These participants were not subjected to any intervention. Receives: Diagnostic Test: Metabolic flexibility in the fasted state; Other: Metabolic flexibility in euglycemic-hyperinsulinemic clamp; Other: Metabolic flexibility in the metabolic chamber |
What is being measured
The primary outcome is the main question the study is designed to answer.
Glucose
Circulating concentration of glucose in mg/dL
Measured: At baseline (in 2008-2009) and after approximately 16 years (2024-2025)
Total cholesterol
Circulating concentration of cholesterol in mg/dL
Measured: At baseline (in 2008-2009) and after approximately 16 years (2024-2025)
HDL cholesterol
Circulating concentration of HDL cholesterol in mg/dL
Measured: At baseline (in 2008-2009) and after approximately 16 years (2024-2025)
LDL cholesterol
Circulating concentration of LDL cholesterol in mg/dL
Measured: At baseline (in 2008-2009) and after approximately 16 years (2024-2025)
Triglycerides
Circulating concentration of triglycerides in mg/dL
Measured: At baseline (in 2008-2009) and after approximately 16 years (2024-2025)
HOMA-IR
Homeostatic Model of Assessment of Insulin Resistance computed from the circulating concentrations of glucose and insulin
Measured: At baseline (in 2008-2009) and after approximately 16 years (2024-2025)
Blood pressure
Including systolic, diastolic, and mean blood pressure in mmHg
Measured: At baseline (in 2008-2009) and after approximately 16 years (2024-2025)
Waist circumference
Measured in cm
Measured: At baseline (in 2008-2009) and after approximately 16 years (2024-2025)
Body mass index
Calculated from the ratio between the weight and height, and expressed in kg/m2
Measured: At baseline (in 2008-2009) and after approximately 16 years (2024-2025)
Body fat percentage
Measured by DXA and expressed as percentage of body weight
Measured: At baseline (in 2008-2009) and after approximately 16 years (2024-2025)
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted1 Apr 2024
- Study start9 Oct 2024
- Primary completion25 Aug 2025
- Study completion27 Aug 2025
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for ObesityStudies 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
- Observational
- Observational model
- Cohort
- Time perspective
- Prospective
- Enrolment
- 18 participants (actual)
Sponsor and investigators
- Lead sponsor
- Pennington Biomedical Research Center
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Rodrigo Fernandez-Verdejo, Pennington Biomedical Research Center
- Investigators
- Rodrigo Fernández-Verdejo, PhD, Principal investigator, Pennington Biomedical Research CenterEric Ravussin, PhD, Principal investigator, Pennington Biomedical Research CenterLeanne Redman, PhD, Principal investigator, Pennington Biomedical Research Center
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06340321
- Sponsor's protocol ID
- PBRC 2023-081
- Acronym
- METPROS
- Status last verified
- Aug 2025
- First submitted
- 25 Mar 2024
- Last updated
- 4 Sep 2025
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Yes: The de-identified data collected will be shared upon appropriate request as part of the NORC repository of Pennington Biomedical Research Center
Study at a glance
From the registry record, last updated by the sponsor on 4 Sep 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Impact of Metabolic Flexibility on Changes in Metabolic Health
- ClinicalTrials.gov ID
- NCT06340321
- Acronym / sponsor ID
- METPROS / PBRC 2023-081
- Conditions
- Obesity, Metabolic Syndrome
- Study type
- Observational
- Recruitment status
- Completed
- Enrolment
- 18 participants (actual)
- Lead sponsor
- Pennington Biomedical Research CenterUniversity, hospital or other
- Study start
- 9 Oct 2024 (actual)
- Primary completion
- 25 Aug 2025 (actual)
- Study completion
- 27 Aug 2025 (actual)
- First posted
- 1 Apr 2024 (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.
Metabolic flexibility is the capacity to adapt fuel oxidation to fuel availability so that ATP synthesis can match its cellular demands. Thus, for example, increases in glucose availability after a meal would increase glucose oxidation, while increases in lipid availability during fasting would increase lipid oxidation. Enhanced metabolic flexibility has been proposed to protect humans from metabolic diseases. Nevertheless, most studies examining associations between metabolic flexibility and metabolic health outcomes have used cross-sectional designs. Whether impaired metabolic flexibility causes or results from metabolic health impairment is thus unclear.
In this study, the investigators will use the data from a study conducted approximately 16 years ago in healthy participants without obesity. Using the data already collected in that study, the metabolic flexibility of each participant will be calculated. To test the association between metabolic flexibility and the change in metabolic health, the investigators will call back all the participants for a single follow-up visit to reassess several metabolic health outcomes. Thus, the main aim of the study is to test the association between metabolic flexibility and the change in metabolic health outcomes after 16 years in humans.
Detailed description
Metabolic flexibility is the capacity to adapt fuel oxidation to fuel availability so that ATP synthesis can match its cellular demands. Thus, for example, increases in glucose availability after a meal would increase glucose oxidation, while increases in lipid availability during fasting would increase lipid oxidation. Enhanced metabolic flexibility has been proposed to protect humans from ectopic lipid accumulation and the subsequent development of insulin resistance and metabolic syndrome.
In humans, metabolic flexibility is assessed by measuring relative macronutrient oxidation (i.e., lipids and carbohydrates) in response to metabolic challenges that increase glucose or lipid availability. The respiratory exchange ratio (RER = CO2 production / O2 consumption) is used to determine relative macronutrient oxidation. The euglycemic-hyperinsulinemic clamp is a widely used challenge to assess metabolic flexibility as it increases glucose availability and thus relative glucose oxidation. Recently, other methods have been proposed to assess metabolic flexibility, including the relative lipid oxidation during an overnight fast or the difference between 24-hour RER and sleeping RER in non-exercise, energy balance conditions while staying in a metabolic chamber. The method most relevant for assessing the influence of metabolic flexibility and its effects on metabolic health outcomes is unknown.
The influence of metabolic flexibility on metabolic health outcomes remains uncertain. The lack of agreement across studies is explained by the variability in the metabolic challenges, differences in the analytical approach to compute metabolic flexibility, and the loose use of the metabolic flexibility concept in the context of many different phenomena. Moreover, most studies examining associations between metabolic flexibility and metabolic health outcomes have used cross-sectional designs. Whether impaired metabolic flexibility causes or results from metabolic health impairment is thus unclear. Longitudinal studies using well-controlled methods are required to determine the impact of metabolic flexibility on prospective metabolic health.
In this pilot and feasibility study, the investigators will use the data from a study conducted 16 years ago in 88 healthy participants without obesity (InSight study at Pennington Biomedical). The study included an euglycemic-hyperinsulinemic clamp, an overnight fasting assessment, a 24-hour stay in a metabolic chamber, and the measurement of metabolic health outcomes. Using the data already collected in the InSight study, the metabolic flexibility of each participant in the euglycemic-hyperinsulinemic clamp, the overnight fast, and the metabolic chamber will be calculated. To test the association between metabolic flexibility(ies) and the change in metabolic health outcomes, the investigators will call back all the participants for a single follow-up visit to reassess the metabolic health outcomes including body mass index, body composition, blood pressure, HOMA-IR, and the circulating concentrations of glucose, triglycerides, and cholesterol. Such data will shed light on the most informative method to assess metabolic flexibility in relationship to specific metabolic health outcomes. The investigators will use these preliminary data to design and power future projects to be submitted for funding to scientific federal agencies.
Our specific aims are to:
- Test the association between metabolic flexibility in response to a euglycemic-hyperinsulinemic clamp and the change in metabolic health outcomes after 16 years in humans.
- Test the association between metabolic flexibility in response to overnight fasting and the change in metabolic health outcomes after 16 years in humans.
- Test the association between metabolic flexibility in response to a 24-hour stay in a metabolic chamber and the change in metabolic health outcomes after 16 years in humans.
Study design
- Observational model
- Cohort
- Time perspective
- Prospective
- Number of arms
- 1
| Arm | Type | Receives |
|---|---|---|
| Insight study cohort | – | Diagnostic Test: Metabolic flexibility in the fasted state, Other: Metabolic flexibility in euglycemic-hyperinsulinemic clamp, Other: Metabolic flexibility in the metabolic chamberThe proposed study will include the individuals who participated in the baseline assessment of the InSight study at Pennington Biomedical in 2008-2009. These participants were not subjected to any intervention. |
Who may qualify
- Ages
- 20 to 65 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
- Study population
- Individuals who participated in the InSight study at Pennington Biomedical in 2008-2009. Such study enrolled healthy men and women aged 20-36 years, with a body mass index <27.5 kg/m2, and a fasting glycemia <126 mg/dL.
Key inclusion criteria (1 listed)
- Individuals who participated in the InSight study at Pennington Biomedical in 2008-2009.
Key exclusion criteria (1 listed)
- Women who are currently pregnant or breastfeeding, have been pregnant in the last 12 months, and/or were breastfeeding in the last 6 months.
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 |
|---|---|---|
| Metabolic flexibility in the fasted stateMeasured at baseline during the InSight study (2008-2009). Calculated as the respiratory exchange ratio in the fasting state adjusted for the circulating concentrations of free fatty acids | Diagnostic test | Insight study cohort |
| Metabolic flexibility in euglycemic-hyperinsulinemic clampMeasured at baseline during the InSight study (2008-2009). Calculated as the change in respiratory exchange ratio adjusted for glucose disposal rate | Other | Insight study cohort |
| Metabolic flexibility in the metabolic chamberMeasured at baseline during the InSight study (2008-2009). Calculated as the difference between awake respiratory exchange ratio (from 8 a.m. to 11 p.m.) and sleeping respiratory exchange ratio during a 23-hour stay in the metabolic chamber | Other | Insight study cohort |
Primary outcome
Glucose
Time frame: At baseline (in 2008-2009) and after approximately 16 years (2024-2025)
Circulating concentration of glucose in mg/dL
Total cholesterol
Time frame: At baseline (in 2008-2009) and after approximately 16 years (2024-2025)
Circulating concentration of cholesterol in mg/dL
HDL cholesterol
Time frame: At baseline (in 2008-2009) and after approximately 16 years (2024-2025)
Circulating concentration of HDL cholesterol in mg/dL
LDL cholesterol
Time frame: At baseline (in 2008-2009) and after approximately 16 years (2024-2025)
Circulating concentration of LDL cholesterol in mg/dL
Triglycerides
Time frame: At baseline (in 2008-2009) and after approximately 16 years (2024-2025)
Circulating concentration of triglycerides in mg/dL
HOMA-IR
Time frame: At baseline (in 2008-2009) and after approximately 16 years (2024-2025)
Homeostatic Model of Assessment of Insulin Resistance computed from the circulating concentrations of glucose and insulin
Blood pressure
Time frame: At baseline (in 2008-2009) and after approximately 16 years (2024-2025)
Including systolic, diastolic, and mean blood pressure in mmHg
Waist circumference
Time frame: At baseline (in 2008-2009) and after approximately 16 years (2024-2025)
Measured in cm
Body mass index
Time frame: At baseline (in 2008-2009) and after approximately 16 years (2024-2025)
Calculated from the ratio between the weight and height, and expressed in kg/m2
Body fat percentage
Time frame: At baseline (in 2008-2009) and after approximately 16 years (2024-2025)
Measured by DXA and expressed as percentage of body weight
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 4 Sep 2025.
- Individual participant dataSharing planned: Yes. The de-identified data collected will be shared upon appropriate request as part of the NORC repository of Pennington Biomedical Research Center
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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.
Rodrigo Fernández-Verdejo, PhD principal investigator
Pennington Biomedical Research Center
Eric Ravussin, PhD principal investigator
Pennington Biomedical Research Center
Leanne Redman, PhD principal investigator
Pennington Biomedical Research Center
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of Obesity and Metabolic Syndrome, run by Pennington Biomedical Research Center at 1 site in United States.
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 1 inclusion and 1 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 4 Sep 2025. 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 United States. 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.
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?
Glucose (time frame: At baseline (in 2008-2009) and after approximately 16 years (2024-2025)). The study lists 10 primary outcomes in all. 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 4 Sep 2025.