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| ID | Type | Description | Link |
|---|---|---|---|
| 17-DK-N004 | Other Identifier | NIDDK |
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One reason people gain weight is eating more calories from food than what they need for energy over 24 hours. Metabolism is the amount of energy a person uses over 24 hours. Researchers want to study the relationship between changes in metabolism and how much a person eats.
Objectives:
To see how much food a person eats when the body's temperature is cooled. To study how changes in metabolism may alter the amount of food a person eats.
Eligibility:
Healthy people ages 18-55.
Design:
Participants will stay at NIH for 20 days.
During the first 4 days, participants will have:
Participants will spend 24-hour periods in a metabolic chamber. The chamber will be at normal room temperature or cooler.
Some times, participants will eat a diet that matches their daily needs (fixed or eucaloric). Other times, they can eat as much as they wish from a vending machine (ad libitum).
Participants will have blood and urine collected.
Participants will swallow an ingestible wireless sensor and wear a small data recorder device.
On the second to last day, participants will stay in the metabolic chamber but only consume water and non-caffeinated sugar-free beverages.
Participants will come back for 1-day visits at six months and one year from the first admission. They will have blood and urine tests, and a DXA scan. They will answer questions on physical activity and food habits.
More than 30% of adults are considered overweight. In general, lifestyle changes (diet and exercise) or current weight loss drugs only lead to about 5 to 10% weight loss. This may be because a person's energy expenditure, aka the number of calories the body uses, leads to hunger and may increase the amount of food a person eats. Cold exposure is known to increase metabolism but it may not lead to weight loss if appetite and the desire for food are also increased. The primary goal of this study is to evaluate whether changing energy expenditure by cool temperature exposure results in changes in food intake. This study will involve a stay on our clinical research unit where we will determine the energy requirements (at 24 degree C) of 68 healthy, adult volunteers without evidence of diabetes. Exposure to cool temperatures (19 degree C) will be used to increase the number of calories a person's body uses in a day. Participants will spend 24 hours in a room that measures energy expenditure while the temperature in the room is turned down, once with a fixed diet (eucaloric) and once with a buffet of food choices (ad libitum). After the fixed diet, volunteers will self-select how much food they wish to eat for one day from a vending machine. Volunteers will also spend one day fasting followed by a day self-selecting their food from the vending machine. Findings from this study will provide knowledge about a possible causal link between energy expenditure and eating behavior. This information may shed light on why many weight loss interventions that increase energy expenditure do not work as well as expected, and may eventually lead to new weight loss approaches and therapies.
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| Label | Type | Description | Intervention Names |
|---|---|---|---|
| 1. Chamber at 24C, fixed diet | Experimental | Chamber at room temperature (24C) with a fixed eucaloric diet |
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| 2. Chamber at 24C, ad libitum diet | Experimental | Chamber at room temperature (24C) with an ad libitum diet (self-select how much food they wish to eat) |
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| 3. Chamber at 19C, fixed diet | Experimental | Chamber at cold temperature (16C) with a fixed eucaloric diet |
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| 4. Chamber at 19C, ad libitum diet | Experimental | Chamber at cold temperature (19C) with an ad libitum diet (self-select how much food they wish to eat) |
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| 5. Chamber at 24C, fasting | Experimental | Chamber at room temperature (24C) fasting while in chamber and 12 hours before |
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| Name | Type | Description | Arm Group Labels | Other Names |
|---|---|---|---|---|
| Cold exposure | Other | 23.25 hours inside respiratory chamber with the temperature set to19°C |
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| Measure | Description | Time Frame |
|---|---|---|
| 24-hour Energy Expenditure (kcal) | Energy expenditure (EE) as measured during 24 hours in a whole-room calorimeter | Days 6 (Chamber at 24°C, fixed diet), 10(Chamber at 24°C, ad libitum diet), 14(Chamber at 19°C, fixed or ad libitum diet), 18(Chamber at 19°C, fixed or ad libitum diet), and 21(Chamber at 24°C, fasting) |
| 24-hour Energy Intake (kcal) | Energy intake as measured during 24 hours in a whole-room calorimeter | Days 6 (Chamber at 24°C, fixed diet), 10(Chamber at 24°C, ad libitum diet), 14(Chamber at 19°C, fixed or ad libitum diet), 18(Chamber at 19°C, fixed or ad libitum diet), and 21(Chamber at 24°C, fasting) |
| Measure | Description | Time Frame |
|---|---|---|
| 24- Hour Respiratory Quotient (RQ) | RQ, an approximation for the ratio of carbohydrate-to-fat oxidation rates, is measured while in the chamber | Days 6 (Chamber at 24°C, fixed diet), 10(Chamber at 24°C, ad libitum diet), 14(Chamber at 19°C, fixed or ad libitum diet), 18(Chamber at 19°C, fixed or ad libitum diet), and 21(Chamber at 24°C, fasting) |
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EXCLUSION CRITERIA:
Age <18 years
Weight greater than or equal to 204 kg (greater than or equal to 450 pounds, maximum weight of the iDXA machine as per manufacturer s manual), or weight <36 kg (<80 pounds, minimum weight allowed based on the NIH guidelines of blood drawing for research purposes)
Use of medications affecting metabolism and appetite in the last three months
Expresses unwillingness to consume all food given during the weight maintaining diet portions of the study (e.g., due to strict dietary restrictions including allergies or vegetarian or kosher diet)
Current use of tobacco products, marijuana, amphetamines, cocaine, or intravenous drug use
Current pregnancy, pregnancy within the past 6 months or lactation
History or clinical manifestation of:
Chronic ethanol use (more than 3 drinks/day)
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| Name | Affiliation | Role |
|---|---|---|
| Douglas Chang, M.D. | National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) | Principal Investigator |
| Facility | Status | City | State | ZIP | Country | Contacts |
|---|---|---|---|---|---|---|
| NIDDK, Phoenix | Phoenix | Arizona | 85014 | United States |
| PubMed Identifier | Type | Citation | Retractions |
|---|---|---|---|
| 41709501 | Derived | Fry HT, Gluck ME, de Baca TC, Stinson EJ, Unlu Y, Piaggi P, Krakoff J, Chang DC. Hunger on the Three-Factor Eating Questionnaire Is Associated With Increased Ad Libitum Energy Intake in Different Conditions. Obesity (Silver Spring). 2026 Apr;34(4):801-810. doi: 10.1002/oby.70148. Epub 2026 Feb 18. | |
| 39675563 | Derived |
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| ID | Title | Description |
|---|---|---|
| FG000 | Chamber at 19°C With Fixed Diet First | Order of chambers will be Chamber at normal room temperature (24°C) with fixed eucaloric diet, Chamber at 24°C with ad libitum diet, Chamber at 19°C with fixed eucaloric diet, Chamber at 19°C with ad libitum diet, and Chamber at 24°C fasting. Normal room temperature: 23.25 hours inside respiratory chamber with the temperature set to 24°C Fixed diet: A diet that matches the participant's caloric needs Ad libitum diet: Participants can eat as much as they want (self-select how much food they wish to eat) |
| FG001 | 2. Chamber at 19°C, ad Libitum Diet First | Order of chambers will be Chamber at normal room temperature (24°C) with fixed eucaloric diet, Chamber at 24°C with ad libitum diet, Chamber at 19°C with ad libitum diet, Chamber at 19°C with fixed eucaloric diet, and Chamber at 24°C fasting. Normal room temperature: 23.25 hours inside respiratory chamber with the temperature set to 24°C Fixed diet: A diet that matches the participant's caloric needs Ad libitum diet: Participants can eat as much as they want (self-select how much food they wish to eat) |
| Title | Milestones | Reasons Not Completed | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Chamber at 24°C, Fixed Diet |
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| Chamber at 24°C, ad Libitum Diet |
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| Chamber at 19°C, Fixed Diet |
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| Chamber at 19°C, ad Libitum Diet |
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| Chamber at 24°C, Fasting |
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| ID | Title | Description |
|---|---|---|
| BG000 | Chamber at 19°C With Fixed Diet First | Order of chambers will be Chamber at normal room temperature (24°C) with fixed eucaloric diet, Chamber at 24°C with ad libitum diet, Chamber at 19°C with fixed eucaloric diet, Chamber at 19°C with ad libitum diet, and Chamber at 24°C fasting. Normal room temperature: 23.25 hours inside respiratory chamber with the temperature set to 24°C Fixed diet: A diet that matches the participant's caloric needs Ad libitum diet: Participants can eat as much as they want (self-select how much food they wish to eat) |
| Units | Counts |
|---|---|
| Participants |
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| Title | Description | Population Description | Parameter Type | Dispersion Type | Unit of Measure | Calculate Percentage | Denominator Units Selected | Denominators | Classes |
|---|---|---|---|---|---|---|---|---|---|
| Age, Continuous | Mean |
| Type | Title | Description | Population Description | Reporting Status | Anticipated Posting Date | Parameter Type | Dispersion Type | Unit of Measure | Calculate Percentage | Time Frame | Units Analyzed | Denominator Units Selected | Arm/Group Information | Denominators | Classes | Analyses | |||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Primary | 24-hour Energy Expenditure (kcal) | Energy expenditure (EE) as measured during 24 hours in a whole-room calorimeter | Posted | Mean | Standard Deviation | kcal | Days 6 (Chamber at 24°C, fixed diet), 10(Chamber at 24°C, ad libitum diet), 14(Chamber at 19°C, fixed or ad libitum diet), 18(Chamber at 19°C, fixed or ad libitum diet), and 21(Chamber at 24°C, fasting) |
|
1 year
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| ID | Title | Description | Deaths (Affected) | Deaths (At Risk) | Serious Events (Affected) | Serious Events (At Risk) | Other Events (Affected) | Other Events (At Risk) |
|---|---|---|---|---|---|---|---|---|
| EG000 | Chamber at 19°C With Fixed Diet First | Order of chambers will be Chamber at normal room temperature (24°C) with fixed eucaloric diet, Chamber at 24°C with ad libitum diet, Chamber at 19°C with fixed eucaloric diet, Chamber at 19°C with ad libitum diet, and Chamber at 24°C fasting. Normal room temperature: 23.25 hours inside respiratory chamber with the temperature set to 24°C Fixed diet: A diet that matches the participant's caloric needs Ad libitum diet: Participants can eat as much as they want (self-select how much food they wish to eat) |
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| Term | Organ System | Source Vocabulary | Assessment Type | Notes | Statistical Information |
|---|---|---|---|---|---|
| Gastroesophageal reflux disease symptoms at Chamber at 24°C, fixed diet | Gastrointestinal disorders | Non-systematic Assessment |
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| Title | Organization | Phone | Extension | |
|---|---|---|---|---|
| Douglas C. Chang, MD | Obesity & Diabetes Clinical Research Section, NIDDK | 602.200.5312 | Douglas.Chang@nih.gov |
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| Type | Includes Protocol | Includes SAP | Includes ICF | Document Label | Document Date | Document Uploaded Date | Document File Name |
|---|---|---|---|---|---|---|---|
| Prot_SAP | Yes | Yes | No | Study Protocol and Statistical Analysis Plan | Mar 23, 2023 | Jun 3, 2025 | Prot_SAP_000.pdf |
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| ID | Term |
|---|---|
| D005247 | Feeding Behavior |
| ID | Term |
|---|---|
| D001522 | Behavior, Animal |
| D001519 | Behavior |
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| ID | Term |
|---|---|
| C407088 | Angptl4 protein, mouse |
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| Normal temperature | Other | 23.25 hours inside respiratory chamber with the temperature set to 24°C |
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| Fixed diet | Other | A diet that matches the participant's caloric needs |
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| Ad libitum diet | Other | Participants can eat as much as they want |
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| Fasting | Other | Participants do not eat for 12 hours before and 24 hours in chamber |
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| Leptin | Plasma leptin (ng/ml) | Days 6 (Chamber at 24°C, fixed diet), 14(Chamber at 19°C, fixed diet) or 18(Chamber at 19°C, fixed diet), and 21(Chamber at 24°C, fasting) |
| Secretin | Plasma secretin (ng/ml) | Days 6 (Chamber at 24°C, fixed diet), 14(Chamber at 19°C, fixed diet) or 18(Chamber at 19°C, fixed diet), and 21(Chamber at 24°C, fasting) |
| Ghrelin | Plasma grehlin (pg/ml) | Days 6 (Chamber at 24°C, fixed diet), 14(Chamber at 19°C, fixed diet) or 18(Chamber at 19°C, fixed diet), and 21(Chamber at 24°C, fasting) |
| FGF-21 | Plasma FGF-21 (pg/ml) | Days 6 (Chamber at 24°C, fixed diet), 14(Chamber at 19°C, fixed diet) or 18(Chamber at 19°C, fixed diet), and 21(Chamber at 24°C, fasting) |
| Core Body Temperature (C) | Core body temperature measured in chamber | Days 6 (Chamber at 24°C, fixed diet), 14(Chamber at 19°C, fixed diet) or 18(Chamber at 19°C, fixed diet), and 21(Chamber at 24°C, fasting) |
| Weight Change at 6 Months | Weight change from baseline to 6 months | 6 months |
| Weight Change at 12 Months | Weight change from baseline to 12 months | 12 months |
| Unlu Y, Piaggi P, Stinson EJ, De Baca TC, Rodzevik TL, Walter M, Fry H, Krakoff J, Chang DC. Cold induces increased ad libitum energy intake independent of changes in energy expenditure: a controlled crossover trial in adults. Am J Clin Nutr. 2025 Feb;121(2):293-303. doi: 10.1016/j.ajcnut.2024.12.013. Epub 2024 Dec 14. |
| 32341039 | Derived | Hollstein T, Heinitz S, Ando T, Rodzevik TL, Basolo A, Walter M, Chang DC, Krakoff J, Piaggi P. Metabolic Responses to 24-Hour Fasting and Mild Cold Exposure in Overweight Individuals Are Correlated and Accompanied by Changes in FGF21 Concentration. Diabetes. 2020 Jul;69(7):1382-1388. doi: 10.2337/db20-0153. Epub 2020 Apr 27. |
| 32118268 | Derived | Hollstein T, Basolo A, Ando T, Votruba SB, Walter M, Krakoff J, Piaggi P. Recharacterizing the Metabolic State of Energy Balance in Thrifty and Spendthrift Phenotypes. J Clin Endocrinol Metab. 2020 May 1;105(5):1375-92. doi: 10.1210/clinem/dgaa098. |
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| BG001 | 2. Chamber at 19°C, ad Libitum Diet First | Order of chambers will be Chamber at normal room temperature (24°C) with fixed eucaloric diet, Chamber at 24°C with ad libitum diet, Chamber at 19°C with ad libitum diet, Chamber at 19°C with fixed eucaloric diet, and Chamber at 24°C fasting. Normal room temperature: 23.25 hours inside respiratory chamber with the temperature set to 24°C Fixed diet: A diet that matches the participant's caloric needs Ad libitum diet: Participants can eat as much as they want (self-select how much food they wish to eat) |
| BG002 | Total | Total of all reporting groups |
| years |
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| Sex: Female, Male | Count of Participants | Participants |
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| Race (NIH/OMB) | Count of Participants | Participants |
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| OG001 | 2. Chamber at 19°C, ad Libitum Diet First | Order of chambers will be Chamber at normal room temperature (24°C) with fixed eucaloric diet, Chamber at 24°C with ad libitum diet, Chamber at 19°C with ad libitum diet, Chamber at 19°C with fixed eucaloric diet, and Chamber at 24°C fasting. Normal room temperature: 23.25 hours inside respiratory chamber with the temperature set to 24°C Fixed diet: A diet that matches the participant's caloric needs Ad libitum diet: Participants can eat as much as they want (self-select how much food they wish to eat) |
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| Primary | 24-hour Energy Intake (kcal) | Energy intake as measured during 24 hours in a whole-room calorimeter | Posted | Mean | Standard Deviation | kcal | Days 6 (Chamber at 24°C, fixed diet), 10(Chamber at 24°C, ad libitum diet), 14(Chamber at 19°C, fixed or ad libitum diet), 18(Chamber at 19°C, fixed or ad libitum diet), and 21(Chamber at 24°C, fasting) |
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| Secondary | 24- Hour Respiratory Quotient (RQ) | RQ, an approximation for the ratio of carbohydrate-to-fat oxidation rates, is measured while in the chamber | Posted | Mean | Standard Deviation | ratio | Days 6 (Chamber at 24°C, fixed diet), 10(Chamber at 24°C, ad libitum diet), 14(Chamber at 19°C, fixed or ad libitum diet), 18(Chamber at 19°C, fixed or ad libitum diet), and 21(Chamber at 24°C, fasting) |
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| Secondary | Leptin | Plasma leptin (ng/ml) | Posted | Mean | Standard Deviation | ng/mL | Days 6 (Chamber at 24°C, fixed diet), 14(Chamber at 19°C, fixed diet) or 18(Chamber at 19°C, fixed diet), and 21(Chamber at 24°C, fasting) |
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| Secondary | Secretin | Plasma secretin (ng/ml) | Posted | Mean | Standard Deviation | ng/mL | Days 6 (Chamber at 24°C, fixed diet), 14(Chamber at 19°C, fixed diet) or 18(Chamber at 19°C, fixed diet), and 21(Chamber at 24°C, fasting) |
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| Secondary | Ghrelin | Plasma grehlin (pg/ml) | Posted | Mean | Standard Deviation | pg/mL | Days 6 (Chamber at 24°C, fixed diet), 14(Chamber at 19°C, fixed diet) or 18(Chamber at 19°C, fixed diet), and 21(Chamber at 24°C, fasting) |
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| Secondary | FGF-21 | Plasma FGF-21 (pg/ml) | Posted | Mean | Standard Deviation | pg/mL | Days 6 (Chamber at 24°C, fixed diet), 14(Chamber at 19°C, fixed diet) or 18(Chamber at 19°C, fixed diet), and 21(Chamber at 24°C, fasting) |
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| Secondary | Core Body Temperature (C) | Core body temperature measured in chamber | Posted | Mean | Standard Deviation | C | Days 6 (Chamber at 24°C, fixed diet), 14(Chamber at 19°C, fixed diet) or 18(Chamber at 19°C, fixed diet), and 21(Chamber at 24°C, fasting) |
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| Secondary | Weight Change at 6 Months | Weight change from baseline to 6 months | Posted | Mean | Standard Deviation | kg | 6 months |
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| Secondary | Weight Change at 12 Months | Weight change from baseline to 12 months | Posted | Mean | Standard Deviation | kg | 12 months |
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| 0 |
| 24 |
| 0 |
| 24 |
| 2 |
| 24 |
| EG001 | 2. Chamber at 19°C, ad Libitum Diet First | Order of chambers will be Chamber at normal room temperature (24°C) with fixed eucaloric diet, Chamber at 24°C with ad libitum diet, Chamber at 19°C with ad libitum diet, Chamber at 19°C with fixed eucaloric diet, and Chamber at 24°C fasting. Normal room temperature: 23.25 hours inside respiratory chamber with the temperature set to 24°C Fixed diet: A diet that matches the participant's caloric needs Ad libitum diet: Participants can eat as much as they want (self-select how much food they wish to eat) | 0 | 30 | 0 | 30 | 1 | 30 |
| Gastroesophageal reflux disease symptoms at Chamber at 19°C, fixed diet | Gastrointestinal disorders | Non-systematic Assessment |
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| Chamber at 19°C, fixed diet |
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| Chamber at 19°C, ad libitum diet |
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| Chamber at 24°C, fasting |
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| Chamber at 19°C, fixed diet |
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| Chamber at 19°C, ad libitum diet |
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| Chamber at 24°C, fasting |
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| Chamber at 24°C, fasting |
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| (Chamber at 24°C, fasting |
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| Chamber at 24°C, fasting |
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| Chamber at 24°C, fasting |
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| Chamber at 24°C, fasting |
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