An observational study in BMI>40, sponsored by Pennington Biomedical Research Center. Not yet recruiting. Open to participants aged 18 Years to 80 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-11-06.
Sponsored by Pennington Biomedical Research Center · Observational
This research will evaluate energy metabolism (expenditure and fat oxidation), metabolic flexibility (response to a high-fat test meal) in 10 individuals with a BMI ≥60 kgm2 using gold-standard assessments of energy metabolism, metabolic flexibility, and body composition. Males and females (18-80 y) with extreme obesity (BMI: ≥60 kg/m2) will be recruited from Baton Rouge, Louisiana. Exclusion criteria include major organ failure, uncontrolled endocrine disease, severe psychiatric illness, pregnancy, and inability to comply with study procedures. The total duration of participation for each individual is estimated at approximately 10 days. If qualified, participants (BMI≥60 kg/m2; n=10) will complete one outpatient visit and one inpatient visit with 36hr metabolic chamber testing.
For visit 1, Subjects will arrive at the outpatient clinic following an overnight fast (nothing to eat or drink, except water, for 10 hours) and the following tests will be performed: anthropometry, blood pressure, pulse rate, temperature, pregnancy test for women, collection of fasting and timed urine samples, fasting and timed blood draws, isotope dilution for sodium bromide, dual-energy X-ray absorptiometry, bioelectrical impedance analysis, ultrasound, accelerometer distribution, and completion of multiple questionnaires. Then, participants will wear the accelerometer and complete an ASA24 questionnaire from Visit 1 to Visit 2-D1, in which participants will return for the first metabolic chamber stay. For D3-Creatine assessment, participants will be instructed to collect an additional urine sample within 5-6 days of Visit 1 that will be dropped off when they arrive for their V2-D1 visit at Pennington Biomedical.
For Visit 2-D1, seven days after being dosed with DLW, subjects will arrive at the inpatient clinic following an overnight fast (nothing to eat or drink, except water, for at least 10 hours). The purpose of this visit is to collect urine samples for D3, DLW, remove the accelerometer, and complete the first overnight metabolic chamber visit, employing a high-fat test meal to assess metabolic flexibility. During this visit, the following tests will be performed: anthropometry, blood pressure, pulse rate, temperature, fasting urine sample, fasting blood draw, accelerometer removal, standardized breakfast and lunch, 13-h overnight stay in the metabolic chamber with a high-fat dinner, urine collection throughout the chamber stay, and VAS before and after lunch and dinner.
Lastly, for Visit 2-D2, upon completing the first overnight inpatient stay in the metabolic chamber (previous 13 hours), participants will exit the chamber at 0700 for one hour to allow for re-calibration of the chambers. Participants will be fasted since their high-fat dinner meal the previous night (approximately 11.5 hours) and will have their metabolic weight taken along with a fasting blood draw. They will then re-enter the metabolic chamber at 0800 and begin a 23-h chamber stay consisting of controlled meals throughout the stay. The purpose of this visit is to collect 23-h chamber data pertaining to various metrics of energy expenditure (e.g., BMR, RMR, TEF, SMR, etc.) and substrate oxidation (i.e., respiratory quotient). During this visit, the following tests will be performed: anthropometry, blood pressure, pulse rate, temperature, fasting blood draw, 23-h stay in the metabolic chamber with controlled meals, urine collection throughout the chamber stay, and VAS before and after lunch and dinner.
After completing of the second overnight chamber stay (Visit 2-D2), participants will exit the metabolic chamber and have their metabolic weight taken.
941 studies on the registry are indexed under Obesity, Morbid; 163 are open to participants now.
This study's planned enrollment of 10 is below the median of 80 across 311 observational studies indexed under Obesity, Morbid.
Browse Obesity, Morbid studies →Pennington Biomedical Research Center is the lead sponsor of 284 studies on the registry; 31 are open to participants now.
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The population for this study is individuals aged 18 to 80 years old who have a BMI greater than or equal to 60 kg/m2 who are willing to consume pre-prepared meals and are willing to have biospecimens and images stored for future use. The reason for seeking to evaluate this specific population is because individuals with extreme obesity possess high surgical and comorbidity risks, but there is a very small amount of research conducted in these individuals.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Diabetic individuals with complications such as:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
BMI (body mass index)
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Ten Males and females (18-80 y) with extreme obesity (BMI: ≥60 kg/m2) will complete one outpatient visit and one inpatient visit with 36 hours of metabolic chamber testing evaluate energy metabolism (expenditure and fat oxidation), metabolic flexibility (response to a high-fat test meal) using gold-standard assessments of energy metabolism, metabolic flexibility, and body composition.
Other: High-fat test meal
At Visit 2-D1, subjects will enter the chamber at approximately 17:30 and exit the following morning at 07:00. Energy expenditure, respiratory exchange ratio (RER), and 12-h oxidation of CHO, fat, and protein will be calculated per standard PBRC protocols. While in the chamber, participants will collect all their urine for measurement of urinary nitrogen. Subjects will be served one high-fat meal while they are in the chamber (40% of the daily energy requirements).
Also known as: metabolic flexibility
24-hour Energy Expenditure
24-hour energy expenditure will be assessed from participants spending 23 hours in a metabolic chamber.
Time frame: Day 9
24-hour Fat Oxidation
This will be collected from the 23-hour chamber stay during Visit 2, Day 2. Specifically, this represents the total grams of fat oxidized over the 23-hour stay, calculated from indirect calorimetry stoichiometry.
Time frame: Day 9
Basal Energy Expenditure
This represents the amount of energy expended under strict basal conditions: post-absorptive (typically 10-12h fasted), thermoneutral, fully awake but supine and motionless, no recent physical activity. This will be collected from the 23-hour metabolic chamber stay.
Time frame: Day 9
Resting Energy Expenditure
This is the energy expended at rest but under less stringent conditions than basal: seated or supine, awake, post-absorptive but with less rigor about prior activity, temperature, and emotional state. This will be collected from the 23-hour metabolic chamber stay.
Time frame: Day 9
Sleeping Metabolic Rate
This is the energy expenditure during sleep, typically computed from the lowest stable \~3-hour window between roughly 02:00 and 05:00 when arousal and movement are minimal. Per our Standard Operating Procedures, this will be computed between 01:00 and 05:00.
Time frame: Day 9
Thermic Effect of Food
This represents the postprandial rise in energy expenditure above the pre-meal baseline, integrated over the period until energy expenditure returns to baseline (typically 4-6 hours for a mixed meal). This reflects the energy cost of digestion, absorption, and substrate processing, plus a sympathetic activation component.
Time frame: Day 9
Spontaneous Physical Activity
This is the energy expended on non-volitional movement: fidgeting, postural adjustments, small spontaneous movements during otherwise sedentary periods in the chamber. It is commonly measured by radar/Doppler motion sensors and quantified either as a fraction of chamber time active (% activity) or as the energy cost of activity above sleeping metabolic rate.
Time frame: Day 9
Free-living Total Daily Energy Expenditure
This is the gold-standard free-living EE measurement: participants drink a dose of ²H₂¹⁸O, and the differential elimination rates of the two isotopes over \~7-14 days yield CO₂ production and therefore EE under habitual living conditions. It captures everything the chamber misses: occupational and recreational activity, environmental temperature variation, real meal patterns.
Time frame: Day 1 to Day 8
Time to Food Quotient
This is the amount of minutes from meal ingestion until RER first reaches (or crosses) the meal's FQ. This represents the speed of the switch of fuel oxidation rather than its endpoint. A flexible system gets there quickly; an inflexible one takes hours or never arrives.
Time frame: Day 8
Respiratory Exchange Ratio: Food Quotient Ratio
This is the measured respiratory exchange ratio divided by the meal's food quotient (the theoretical RER if the meal were fully oxidized as ingested). A ratio of 1.0 means whole-body substrate oxidation has fully matched the macronutrient composition of what was just eaten; \<1.0 means oxidation is lagging behind intake (fat-dominant fuel selection persisting after a mixed or high-carb meal); \>1.0 means net lipogenesis or carryover carb oxidation. The FQ of the high-fat test meal will be used.
Time frame: Day 8
ΔRespiratory Exchange Ratio Nadir
This represents the drop from a reference RER (typically pre-meal fasting baseline, sometimes overnight minimum) to the lowest RER value observed. In a high-fat meal challenge this captures the magnitude of the fat-oxidation excursion: how far down the RER pushes when the meal is fat-dominant.
Time frame: Day 8
Post-meal Respiratory Exchange Ratio Slope
This represents the rate of RER change in the early postprandial window, usually fit as a linear slope over the first 30-90 minutes after ingestion. A steep slope would mean a rapid switch (metabolically flexible) and a shallow slope would indicate impaired metabolic flexibility.
Time frame: Day 8
Time to Respiratory Exchange Ratio Nadir
This represents the amount of minutes from high-fat meal meal ingestion until RER reaches its lowest value. Pairing this will the change in RER nadir helps describe the fat oxidation excursion. That is, nadir magnitude expresses how much fat oxidation increased, whereas time-to-nadir exhibits how long it took to get there.
Time frame: Day 8
Skeletal Muscle Mass
Skeletal muscle mass will be measured using D3-creatine dilution. Participants will be administered a 60 mg capsule with D3-creatine during Visit 1. Spot urine specimens will be collected between 120 hours (5 days) and 144 hours (6 days) after administration of the D3-creatine dose.
Time frame: Day 1 to Day 5
Fat-free Mass
Fat-free mass will be quantified by dual-energy X-ray absorptiometry and two bioelectrical impedance analysis devices (InBody S10 and ImpediMed SFB7) during visit 1.
Time frame: Day 1
Fat Mass
Fat mass will be estimated by dual-energy X-ray absorptiometry and two bioelectrical impedance analysis devices (InBody S10 and ImpediMed SFB7) during visit 1.
Time frame: Day 1
Body Fat Percentage
Body fat percentage will be estimated by dual-energy X-ray absorptiometry and two bioelectrical impedance analysis devices (InBody S10 and ImpediMed SFB7) during visit 1.
Time frame: Day 1
Extracellular Water
At Visit 1, a blood sample of 3 ml will be collected before ingesting an appropriate amount of sodium bromide based on body weight diluted in deionized water. A blood sample of 3 ml will be collected 4 hours after ingestion. During the 4-hour period participants must refrain from eating anything, but they can drink water if needed.
Time frame: Day 1
Total Body Water
Total body water will be determined via two bioelectrical impedance devices (InBody S10 and ImpediMed SFB7) and deuterium dilution.
Time frame: Day 1
No study locations are listed for this record.
Plan to share: Undecided
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
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