ObesityLOWSNCT05289310
Low Oxygen Exposure and Weight Status
A study testing Normobaric hypoxia (NH) and Normobaric normoxia (NN) in people with Obesity, run by Pennington Biomedical Research Center at 1 site in United States.
Trial summary
The objective of the proposed double-blind, parallel-arm, randomized clinical trial is to evaluate changes in body weight and composition, assess determinants of energy balance (intake and expenditure), and measure modulators of energy balance, following 8 wk of calorie restriction (-500 kcal/d) in combination with… Read more about this study
- Who is it for?
- Ages 22 to 65 yearsHealthy volunteers can take part
- Conditions the study is for
- Obesity
- What is being tested?
- Normobaric hypoxia (NH) and Normobaric normoxia (NN)
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 60 participants
- Where
- 1 siteUnited States
- Study dates
- 16 May 2023to 30 Apr 2027
- Phase
- Interventional
- Are there results?
- Not yet: the study is under way
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 22 to 65 years
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Who may be able to join
- Obese (BMI between 30-39.9 kg/m2)
- Born at altitudes below 2,100 meters (~7,000 feet)
- Currently residing in Tallahassee, Florida or surrounding area
- Completed a full FDA authorized or approved COVID-19 vaccination series at least 14 days before any in-person human research activity.
- Not taking any medication(s) that interfere with oxygen delivery/transport for 4 weeks prior to and throughout the entire study (e.g., includes sedatives, sleeping aids, tranquilizers and/or any medication that depresses ventilation, diuretics, alpha and beta blockers).
- Willing to refrain from smoking, vaping, chewing tobacco, and dietary supplement use throughout the entire study.
- Willing to have a hypoxic tent set-up in their home and spend 8 consecutive hours per night in the tent for 8 weeks
- Lives with a family member, partner/spouse, or roommate who can hear and respond in the unlikely event that the blood oxygen, air oxygen, or air carbon dioxide monitoring alarm would sound.
Who cannot join
- Living in areas that are more than 1,200 m (~4,000 feet), or have traveled to areas that are more than 1,200 m for five days or more within the last 2 months
- Individuals who have not completed a full FDA authorized or approved COVID-19 vaccination series at least 14 days before any in-person human research activity.
- Cardiovascular abnormalities, gastrointestinal disorders, or any condition that interferes with oxygen delivery/transport (e.g., kidney disease, cardiovascular disease, etc.)
- Oxygen saturation < 95% while awake or oxygen saturation dips below 88% for a total of ≥ 10 min overnight in normoxic conditions
- Evidence of apnea or other sleeping disorders
- Evidence of prior high-altitude pulmonary edema (HAPE) or high-altitude cerebral edema (HACE) diagnosis
Show all 14Show fewer
- Diagnosis or family history of sickle cell anemia/trait
- Hematocrit <42% for males, <36% for females
- Hemoglobin <13 g/dL for males, <12 g/dL for females
- Blood donation within 8 weeks of beginning the study
- Present condition of alcoholism, anabolic steroids, or other substance abuse issues
- Women who are pregnant, lactating, planning to become pregnant, or who have had an irregular menstrual cycle in the past 6 mo.
- Weight gain or loss > 10% of body weight during the past 6 months
- Adults unable to consent
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
United States1 site, 1 recruiting
- Recruiting
Pennington Biomedical Research Center
Baton Rouge, Louisiana, 70808
Claire E Berryman, PhD,RD, claire.berryman@pbrc.edu
About this study
Official title: Effects of Daily Low Oxygen Exposure on Weight Status, Body Composition, and Metabolic Health
The objective of the proposed double-blind, parallel-arm, randomized clinical trial is to evaluate changes in body weight and composition, assess determinants of energy balance (intake and expenditure), and measure modulators of energy balance, following 8 wk of calorie restriction (-500 kcal/d) in combination with either overnight exposure to normobaric hypoxia (8 h/night, 15% FiO2, ~2640 m) or normoxia (8 h/night, 21% FiO2), using a commercially available, in-home tent system, in adults with obesity.
Read the detailed description
Obesity and associated metabolic conditions are a significant public health burden, costing the U.S. ~$150 billion annually. Obesity is both a disease, affecting 1 in 3 Americans, and a risk factor for other chronic diseases, such as cardiovascular disease, type 2 diabetes, and 13 forms of cancers. Diet and exercise are the cornerstone of obesity prevention and treatment. However, a considerable number of individuals are non-responsive to existing weight-loss interventions and obesity rates continue to rise. Therefore, non-conventional approaches are needed to supplement current weight-loss strategies. Daily exposure to low-oxygen conditions may aid in current weight- loss strategies. Moderate (1500-3500 m) and higher (≥ 3500 m) altitude environments are naturally hypoxic due to the lower atmospheric pressure (for reference, Denver, CO is ~1600 m and Mt. Hood in Oregon is ~3500 m). Studies show that sea-level natives exposed to moderate- or high- altitude continuously for 5 or more days lose weight, which is a consequence of prolonged reductions in blood and tissue oxygenation that lead to increased energy expenditure and decreased appetite. However, implementation of hypoxia as a means for weight loss has been limited, to date, by the logistical constraints of traveling to remote locations or access to an altitude chamber. A safe, less expensive, and more logistically feasible alternative is the use of commercially available, low-oxygen systems at sea level, which create a normobaric hypoxic environment. Whether in-home, overnight, normobaric hypoxic exposure, compared to normobaric normoxic exposure, promotes body mass loss in adults with obesity remains unknown. Furthermore, determinants of energy balance, including energy intake and expenditure, and their relative contribution to normobaric hypoxia-induced weight loss have not been investigated. The objective of the proposed double-blind, parallel-arm, randomized clinical trial is to evaluate changes in body weight and composition, assess determinants of energy balance (intake and expenditure), and measure modulators of energy balance, following 8 wk of calorie restriction (-500 kcal/d) in combination with either overnight exposure to normobaric hypoxia (8 h/night, 15% FiO2, ~2640 m) or normoxia (8 h/night, 21% FiO2), using a commercially available, in-home tent system, in adults with obesity. Chronic (8 weeks), overnight (8 hours/night) low oxygen exposure may provide a non-conventional approach to supplement current weight-loss strategies, inform new strategies to accelerate weight loss, aid long-term weight management efforts, and benefit metabolic health in individuals with obesity.
- Conditions
- Obesity
- Being tested
- Normobaric hypoxia (NH), Normobaric normoxia (NN)
- Keywords
- Body weight, Normobaric hypoxia, Negative energy balance, Energy intake, Energy expenditure
- Medical subject headings
- Obesity, Body Weight
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Normobaric hypoxia (NH)Other
Low oxygen exposure to mimic ~8500 feet elevation (experimental).
Normobaric normoxia (NN)Other
Normal oxygen exposure to mimic sea level conditions (sham comparator).
| Study group | Role | What they receive |
|---|---|---|
| Normobaric hypoxia (NH) | Experimental | 8 weeks of overnight exposure (8 hrs/night) to NH conditions (~15% oxygen; achieved with nitrogen dilution, equivalent to ~8500 feet elevation) using a commercially available tent and generator system (Hypoxico, Inc., New York, NY). Receives: Other: Normobaric hypoxia (NH) |
| Normobaric normoxia (NN) | Sham comparator | 8 weeks of overnight exposure (8 hrs/night) to NN conditions (~21% oxygen; sea level) using a commercially available tent and generator system (Hypoxico, Inc., New York, NY). Receives: Other: Normobaric normoxia (NN) |
What is being measured
The primary outcome is the main question the study is designed to answer.
Change in body weight
Body weight will be measured during the baseline weight maintenance phase (days -14 to 0) and each morning during the study (days 1 to 56) following an overnight fast and morning void, using a calibrated digital scale provided to participants to use at home (A\&D Medical wireless weight scale UC-352BLE, San Jose, CA). Change in body weight will be calculated as: body weight on day 56 - baseline body weight (average of days -14 to 0).
Measured: 10 weeks (70 days)
Secondary outcomes (30)
4-compartment body composition using DEXA and deuterium dilution
Body composition will be determined following at least a 10 hour fast and morning void on day -7 and 49 using dual energy x-ray absorptiometry (DEXA, Discovery W, Hologic Inc., Bedford, MA or equivalent). The volunteer will remove all metal-containing objects from their body, lay face-up on the DEXA densitometer table in light clothing (t-shirt, shorts, socks), and be asked to remain motionless for the 8-10 min scan. A scanner emitting low energy x-rays and a detector will pass over the participant. These data will be used to calculate total body mass, fat-free mass, fat mass, and bone mass. Total body water will be measured following at least a 10 hour fast and 1 hour without water intake using oxygen-18 labeled water on days -7 and 49.
Measured: Days -7 and 49
Waist circumference
Waist circumference will be measured to the nearest centimeter using a measuring tape. Measurements will be taken in duplicate.
Measured: Days -7 and 49
Blood volume
Blood volume will be determined using the optimized carbon monoxide rebreathing method on days -7 and 49. In this method, a finger stick blood sample is taken and basal carboxyhemoglobin concentrations determined using a blood gas analyzer (OSM-3, Radiometer). Carbon monoxide is then inhaled via a spirometer (SpiCo, Blood Tec.) for 2 min. Seven minutes after inhaling the carbon monoxide bolus, a second finger prick blood sample is taken to determine the increase in carboxyhemoglobin concentration. The change in percentage of carboxyhemoglobin between the basal and second measurements can be used to calculate hemoglobin mass and blood volume.
Measured: Days -7 and 49
Total daily energy expenditure (TDEE)
Energy expenditure will be assessed by the doubly labeled water (DLW) method. Briefly, upon waking, volunteers will provide a urine sample and completely void their bladder, this sample will be used to measure background isotope enrichment. The participant will then consume 1.5 g/kg of 10% O18 and 0.06 g/kg of deuterium. Urine samples will be collected at 4 h, 6.5 h, 24 h, 3 d, 5 d, and 7 d after dosing.
Measured: Days -7 to 0 and 49-56
Resting metabolic rate
Resting metabolic rate will be measured with open circuit, indirect calorimetry (ParvoMedics TrueOne 2400 metabolic cart, Sandy, UT) in the morning, upon arrival to the lab on days 0 and 56.
Measured: Days 0 and 56
Resting substrate oxidation
Resting substrate oxidation will be measured with open circuit, indirect calorimetry (ParvoMedics TrueOne 2400 metabolic cart, Sandy, UT) in the morning, upon arrival to the lab on days 0 and 56.
Measured: Days 0 and 56
Ad libitum energy intake
Participants will be provided an ad libitum mixed-macronutrient meal (e.g., frozen lasagna) on days 0 and 56. Food will be provided in excess of expected consumption for one individual. Water in the amount of 240 g will be provided during the meal. Participants will be instructed to consume all water before completing the meal and will not be permitted additional water during the meal, in order to control the effect of fluid intake on satiety. To limit social influence on eating behavior, each ad libitum meal will be consumed in isolation. Leftover food will be collected and weighed after participants have left the laboratory. Energy and nutrient content of the amount consumed will be determined using Food Processor software (version 11.6.0, ESHA Research, Salem, OR) under the supervision of a Registered Dietitian.
Measured: Days 0 and 56
Subjective appetite measures
Subjective appetite will be measured on study days 0 and 56. Subjectively rated appetite will be assessed immediately before the oral glucose tolerance test (OGTT), at 15, 30, 45, 60, 90, and 120 minutes after beginning the OGTT, and upon cessation of the ad libitum meal (discussed above) using 100 mm visual analog scales to rate fullness, hunger, desire to eat, and prospective food consumption. Composite satiety score will be calculated from the individual appetite scores using the equation: CSS = (fullness + (100 - Desire to eat) + (100 - Hunger) + (100 - Prospective food consumption) / 4.
Measured: Days 0 and 56
Overnight oxygen saturation (wrist-worn device)
Participants will be provided a wrist-worn device with Bluetooth capabilities (vivosmart 4, Garmin, Olathe, KS) to be worn for 2 weeks prior to the start of the study (baseline measurement) and continuously for the entirety of the study. This devise will measure steps, physical activity levels, heart rate, overnight oxygen saturation, and sleep patterns.
Measured: 10 weeks (70 days)
Overnight oxygen saturation (index finger pulse oximetry)
In addition to the wrist-worn physical activity monitoring device (vivosmart 4, Garmin, Olathe, KS) that will measure overnight oxygen saturation, participants also will wear a pulse oximeter (PalmSAT® 2500A) on their index finger overnight to measure oxygen saturation.
Measured: 10 weeks (70 days)
Prevalence of acute mountain sickness
The prevalence and severity of AMS will be determined from information gathered using the shortened version of the Environmental Symptoms Questionnaire (ESQ) and the Lake Louise AMS Scoring System (LLS; 5 min; 26 questions total). At completion of the questionnaire, oxygen saturation will be determined using finger pulse oximetry (PalmSAT® 2500A, Nonin Medical, Inc., Plymouth, MN). AMS and oxygen saturation measurements will be taken in the morning (between 5:00-8:00am, inside tent) and evening (9:00pm-12:00am, inside tent) on days 0-7, 14, 21, 28, 35, 42, and 56.
Measured: Days 0-7, 14, 21, 28, 35, 42, and 56
Heart rate variability
A 3-lead electrocardiogram will be conducted on days 0 and 56 to assess heart rate variability. Participants will have electrode patches placed on their chest to measure the electrical activity of the heart.
Measured: Days 0 and 56
Heart rate variability
Participants will be provided a wrist-worn device with Bluetooth capabilities (vivosmart 4, Garmin, Olathe, KS) to be worn for 2 weeks prior to the start of the study (baseline measurement) and continuously for the entirety of the study. This devise will measure steps, physical activity levels, heart rate, overnight oxygen saturation, and sleep patterns.
Measured: 10 weeks (70 days)
Urinary epinephrine
On days -1, 13, and 55 urine will be collected during the overnight time period. Participants will void their bladder before entering the tent in the evening (they will not collect this portion). Participants will collect any urine produced throughout the night and will collect one final time in the morning after exiting the tent. Epinephrine concentrations in the urine samples will be measured.
Measured: Days -1, 13, and 55
Urinary norepinephrine
On days -1, 13, and 55 urine will be collected during the overnight time period. Participants will void their bladder before entering the tent in the evening (they will not collect this portion). Participants will collect any urine produced throughout the night and will collect one final time in the morning after exiting the tent. Norepinephrine concentrations in the urine samples will be measured.
Measured: Days -1, 13, and 55
Urinary dopamine
On days -1, 13, and 55 urine will be collected during the overnight time period. Participants will void their bladder before entering the tent in the evening (they will not collect this portion). Participants will collect any urine produced throughout the night and will collect one final time in the morning after exiting the tent. Dopamine concentrations in the urine samples will be measured.
Measured: Days -1, 13, and 55
Plasma glucose concentrations
A 75-g oral glucose tolerance test (OGTT) will be conducted on days 0 and 56. A venous catheter will be placed and blood samples obtained at -5, 30, 60, 90, and 120 min during the OGTT for measurements of plasma glucose and insulin concentration. Insulin sensitivity will be determined by using the whole-body insulin sensitivity index (WBISI), also known as the Matsuda Index.
Measured: Days 0 and 56
Plasma insulin concentrations
A 75-g oral glucose tolerance test (OGTT) will be conducted on days 0 and 56. A venous catheter will be placed and blood samples obtained at -5, 30, 60, 90, and 120 min during the OGTT for measurements of plasma glucose and insulin concentration. Insulin sensitivity will be determined by using the whole-body insulin sensitivity index (WBISI), also known as the Matsuda Index.
Measured: Days 0 and 56
Whole-body insulin sensitivity index
A 75-g oral glucose tolerance test (OGTT) will be conducted on days 0 and 56. A venous catheter will be placed and blood samples obtained at -5, 30, 60, 90, and 120 min during the OGTT for measurements of plasma glucose and insulin concentration. Insulin sensitivity will be determined by using the whole-body insulin sensitivity index (WBISI), also known as the Matsuda Index.
Measured: Days 0 and 56
Thermic effect of glucose
The thermic effect of glucose will be measured on study days 0 and 56 with open circuit, indirect calorimetry (2400 TrueOne, Parvo Medics) using established protocols. Resting metabolic rate measurements will be taken prior to glucose administration in a thermo-neutral room while the participant is in the supine position (as described above). During the oral glucose tolerance test the thermic effect of glucose will be measured in 15 min increments for 2 hours (15-30, 45-60, 75-90, and 105-120 minutes).
Measured: Days 0 and 56
24-hour continuous glucose concentrations
A continuous glucose monitor (Freestyle Libre Pro) will be inserted into the subcutaneous adipose tissue behind the arm and will be used to collect and assess 24-hour glucose concentrations.
Measured: Days -14-0, 1-14, and 42-56
24-hour glucose variability
A continuous glucose monitor (Freestyle Libre Pro) will be inserted into the subcutaneous adipose tissue behind the arm and will be used to collect and assess 24-hour glucose concentrations.
Measured: Days -14-0, 1-14, and 42-56
Assessment of sleep
Participants will be provided a wrist-worn device with Bluetooth capabilities (vivosmart 4, Garmin, Olathe, KS) to be worn for 2 weeks prior to the start of the study (baseline measurement) and continuously for the entirety of the study. This devise will measure steps, physical activity levels, heart rate, overnight oxygen saturation, and sleep patterns.
Measured: 10 weeks (70 days)
Pittsburgh Sleep Quality Index
The Pittsburgh Sleep Quality Index will be used to examine participant sleep quality on days -1, 14, and 56 (5 min; 18 questions total).
Measured: Days -1, 14, and 56
Subjective sleep quality
Participants will be asked to complete a sleep diary before and after sleep for 7 d at baseline, on days 0-14, and on days 49-56. The sleep diary includes questions related to mood, caffeine intake, substance use (e.g. alcohol, caffeine, and prescriptions), and sleep quality.
Measured: Days -7-0, 1-14, and 49-56
Fasting measures of iron status
Serum iron, total iron binding capacity, soluble transferrin receptor, hepcidin, hemoglobin, hematocrit, ferritin, erythroferrone, and erythropoietin will be measured in fasting blood samples collected on days 0 and 56.
Measured: Days 0 and 56
Psychosocial Factors
The Positive and Negative Affect Schedule (PANAS), Cohen Perceived Stress Scale, Big Five Inventory-2, Delay Discounting questionnaire, Palatable Eating Motives Scale, and the Generalized Self-Efficacy scale will be administered on day 0, 14, and 56.
Measured: Days 0, 14, and 56
Fasting blood pressure
Participants will rest in a seated position for at least 5 minutes before an automated blood pressure cuff is used to measure blood pressure in triplicate.
Measured: Days -7 and 49
Barrier Questionnaire
This questionnaire will be administered to participants on day 56 to assess real and perceived barriers to sleeping in a hypoxic tent (5 min; 17 questions total).
Measured: Day 56
Change in body weight
Body weight also will be measured 4 weeks after the study intervention ends to assess whether weight loss is sustained. Change in body weight will be calculated as:
- Body weight on day 84 (i.e., 4 wk post-intervention) - baseline body weight (average of days -14 to 0)
- Body weight on day 84 (i.e., 4 wk post-intervention) - body weight on day 56
Measured: 4 weeks after intervention ends
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted21 Mar 2022
- Study start16 May 2023
- Primary completion31 Oct 2026 (estimated)
- Study completion30 Apr 2027 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (1)Papers the sponsor has linked to this study.
- 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
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Quadruple blind
- Who is masked
- Participant, Care provider, Investigator, Outcomes assessor
- Enrolment
- 60 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Pennington Biomedical Research Center
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Claire Berryman, Pennington Biomedical Research Center
- Investigators
- Claire E. Berryman, PhD, RD, Principal investigator, Pennington Biomedical Research Center
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05289310
- Sponsor's protocol ID
- PBRC 2022-046
- Other IDs
- 1R01DK127162-01A1
- Acronym
- LOWS
- Status last verified
- Jul 2026
- First submitted
- 13 Mar 2022
- Last updated
- 16 Jul 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Publications
Riley TM, Weschenfelder C, Ravussin E, Rood JC, Greenway F, Taff S, Hickner RC, Cao H, Sutin AR, Todd G, Hennigar SR, Berryman CE. Effects of daily low oxygen exposure on weight status, body composition, and metabolic health in adults with obesity: protocol for a randomized, double-blind, controlled-feeding study. Contemp Clin Trials. 2026 Jan;160:108167. doi: 10.1016/j.cct.2025.108167. Epub 2025 Nov 26.
PubMed 41314599
Study at a glance
From the registry record, last updated by the sponsor on 16 Jul 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Effects of Daily Low Oxygen Exposure on Weight Status, Body Composition, and Metabolic Health
- ClinicalTrials.gov ID
- NCT05289310
- Acronym / sponsor ID
- LOWS / PBRC 2022-046
- Conditions
- Obesity
- Keywords
- Body weight, Normobaric hypoxia, Negative energy balance, Energy intake, Energy expenditure
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 60 participants (estimated)
- Lead sponsor
- Pennington Biomedical Research CenterUniversity, hospital or other
- Collaborators
- National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
- Study start
- 16 May 2023 (actual)
- Primary completion
- 31 Oct 2026 (estimated)
- Study completion
- 30 Apr 2027 (estimated)
- First posted
- 21 Mar 2022 (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.
The objective of the proposed double-blind, parallel-arm, randomized clinical trial is to evaluate changes in body weight and composition, assess determinants of energy balance (intake and expenditure), and measure modulators of energy balance, following 8 wk of calorie restriction (-500 kcal/d) in combination with either overnight exposure to normobaric hypoxia (8 h/night, 15% FiO2, ~2640 m) or normoxia (8 h/night, 21% FiO2), using a commercially available, in-home tent system, in adults with obesity.
Detailed description
Obesity and associated metabolic conditions are a significant public health burden, costing the U.S. ~$150 billion annually. Obesity is both a disease, affecting 1 in 3 Americans, and a risk factor for other chronic diseases, such as cardiovascular disease, type 2 diabetes, and 13 forms of cancers. Diet and exercise are the cornerstone of obesity prevention and treatment. However, a considerable number of individuals are non-responsive to existing weight-loss interventions and obesity rates continue to rise. Therefore, non-conventional approaches are needed to supplement current weight-loss strategies. Daily exposure to low-oxygen conditions may aid in current weight- loss strategies. Moderate (1500-3500 m) and higher (≥ 3500 m) altitude environments are naturally hypoxic due to the lower atmospheric pressure (for reference, Denver, CO is ~1600 m and Mt. Hood in Oregon is ~3500 m). Studies show that sea-level natives exposed to moderate- or high- altitude continuously for 5 or more days lose weight, which is a consequence of prolonged reductions in blood and tissue oxygenation that lead to increased energy expenditure and decreased appetite. However, implementation of hypoxia as a means for weight loss has been limited, to date, by the logistical constraints of traveling to remote locations or access to an altitude chamber. A safe, less expensive, and more logistically feasible alternative is the use of commercially available, low-oxygen systems at sea level, which create a normobaric hypoxic environment. Whether in-home, overnight, normobaric hypoxic exposure, compared to normobaric normoxic exposure, promotes body mass loss in adults with obesity remains unknown. Furthermore, determinants of energy balance, including energy intake and expenditure, and their relative contribution to normobaric hypoxia-induced weight loss have not been investigated. The objective of the proposed double-blind, parallel-arm, randomized clinical trial is to evaluate changes in body weight and composition, assess determinants of energy balance (intake and expenditure), and measure modulators of energy balance, following 8 wk of calorie restriction (-500 kcal/d) in combination with either overnight exposure to normobaric hypoxia (8 h/night, 15% FiO2, ~2640 m) or normoxia (8 h/night, 21% FiO2), using a commercially available, in-home tent system, in adults with obesity. Chronic (8 weeks), overnight (8 hours/night) low oxygen exposure may provide a non-conventional approach to supplement current weight-loss strategies, inform new strategies to accelerate weight loss, aid long-term weight management efforts, and benefit metabolic health in individuals with obesity.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Quadruple blind (participant, care provider, investigator, outcomes assessor)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Normobaric hypoxia (NH) | Experimental | Other: Normobaric hypoxia (NH)8 weeks of overnight exposure (8 hrs/night) to NH conditions (~15% oxygen; achieved with nitrogen dilution, equivalent to ~8500 feet elevation) using a commercially available tent and generator system (Hypoxico, Inc., New York, NY). |
| Normobaric normoxia (NN) | Sham comparator | Other: Normobaric normoxia (NN)8 weeks of overnight exposure (8 hrs/night) to NN conditions (~21% oxygen; sea level) using a commercially available tent and generator system (Hypoxico, Inc., New York, NY). |
Who may qualify
- Ages
- 22 to 65 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (8 listed)
- Obese (BMI between 30-39.9 kg/m2)
- Born at altitudes below 2,100 meters (~7,000 feet)
- Currently residing in Tallahassee, Florida or surrounding area
- Completed a full FDA authorized or approved COVID-19 vaccination series at least 14 days before any in-person human research activity.
- Not taking any medication(s) that interfere with oxygen delivery/transport for 4 weeks prior to and throughout the entire study (e.g., includes sedatives, sleeping aids, tranquilizers and/or any medication that depresses ventilation, diuretics, alpha and beta blockers).
Key exclusion criteria (14 listed)
- Living in areas that are more than 1,200 m (~4,000 feet), or have traveled to areas that are more than 1,200 m for five days or more within the last 2 months
- Individuals who have not completed a full FDA authorized or approved COVID-19 vaccination series at least 14 days before any in-person human research activity.
- Cardiovascular abnormalities, gastrointestinal disorders, or any condition that interferes with oxygen delivery/transport (e.g., kidney disease, cardiovascular disease, etc.)
- Oxygen saturation < 95% while awake or oxygen saturation dips below 88% for a total of ≥ 10 min overnight in normoxic conditions
- Evidence of apnea or other sleeping disorders
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 |
|---|---|---|
| Normobaric hypoxia (NH)Low oxygen exposure to mimic ~8500 feet elevation (experimental). | Other | Normobaric hypoxia (NH) |
| Normobaric normoxia (NN)Normal oxygen exposure to mimic sea level conditions (sham comparator). | Other | Normobaric normoxia (NN) |
Primary outcome
Change in body weight
Time frame: 10 weeks (70 days)
Body weight will be measured during the baseline weight maintenance phase (days -14 to 0) and each morning during the study (days 1 to 56) following an overnight fast and morning void, using a calibrated digital scale provided to participants to use at home (A\&D Medical wireless weight scale UC-352BLE, San Jose, CA). Change in body weight will be calculated as: body weight on day 56 - baseline body weight (average of days -14 to 0).
30 secondary outcomes
4-compartment body composition using DEXA and deuterium dilution
Time frame: Days -7 and 49
Waist circumference
Time frame: Days -7 and 49
Blood volume
Time frame: Days -7 and 49
Total daily energy expenditure (TDEE)
Time frame: Days -7 to 0 and 49-56
Resting metabolic rate
Time frame: Days 0 and 56
Resting substrate oxidation
Time frame: Days 0 and 56
Ad libitum energy intake
Time frame: Days 0 and 56
Subjective appetite measures
Time frame: Days 0 and 56
Overnight oxygen saturation (wrist-worn device)
Time frame: 10 weeks (70 days)
Overnight oxygen saturation (index finger pulse oximetry)
Time frame: 10 weeks (70 days)
Prevalence of acute mountain sickness
Time frame: Days 0-7, 14, 21, 28, 35, 42, and 56
Heart rate variability
Time frame: Days 0 and 56
Heart rate variability
Time frame: 10 weeks (70 days)
Urinary epinephrine
Time frame: Days -1, 13, and 55
Urinary norepinephrine
Time frame: Days -1, 13, and 55
Urinary dopamine
Time frame: Days -1, 13, and 55
Plasma glucose concentrations
Time frame: Days 0 and 56
Plasma insulin concentrations
Time frame: Days 0 and 56
Whole-body insulin sensitivity index
Time frame: Days 0 and 56
Thermic effect of glucose
Time frame: Days 0 and 56
24-hour continuous glucose concentrations
Time frame: Days -14-0, 1-14, and 42-56
24-hour glucose variability
Time frame: Days -14-0, 1-14, and 42-56
Assessment of sleep
Time frame: 10 weeks (70 days)
Pittsburgh Sleep Quality Index
Time frame: Days -1, 14, and 56
Subjective sleep quality
Time frame: Days -7-0, 1-14, and 49-56
Fasting measures of iron status
Time frame: Days 0 and 56
Psychosocial Factors
Time frame: Days 0, 14, and 56
Fasting blood pressure
Time frame: Days -7 and 49
Barrier Questionnaire
Time frame: Day 56
Change in body weight
Time frame: 4 weeks after intervention ends
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 16 Jul 2026.
- Derived from this study: PubMed 41314599Riley TM, Weschenfelder C, Ravussin E, Rood JC, Greenway F, Taff S, Hickner RC, Cao H, Sutin AR, Todd G, Hennigar SR, Berryman CE. Effects of daily low oxygen exposure on weight status, body composition, and metabolic health in adults with obesity: protocol for a randomized, double-blind, controlled-feeding study. Contemp Clin Trials. 2026 Jan;160:108167. doi: 10.1016/j.cct.2025.108167. Epub 2025 Nov 26.
- Individual participant dataSharing planned: No
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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.
Claire E. Berryman, PhD, RD 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?
A study testing Normobaric hypoxia (NH) and Normobaric normoxia (NN) in people with Obesity, 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 8 inclusion and 14 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: looking for participants now, as of the sponsor's last update on 16 Jul 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 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. Some participants in this study may receive a placebo. 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?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Claire E. Berryman, PhD, RD (3042161050, claire.berryman@pbrc.edu), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Change in body weight (time frame: 10 weeks (70 days)). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT05289310, which also lists 1 linked publication.
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 16 Jul 2026.