Obesity (Disorder)LOWS-IRONNCT07542873
Iron Absorption in The Low Oxygen Exposure and Weight Status (LOWS) Study
A study testing Normobaric hypoxia (NH) and Normobaric normoxia (NN) in people with Obesity (Disorder), run by Pennington Biomedical Research Center at 1 site in United States.
Trial summary
Declines in iron status are common in those with obesity and may be due to obesity-related chronic inflammation; however, the effects of reducing inflammation following diet-induced weight loss on iron metabolism are poorly understood. Read more about this study
- Who is it for?
- Ages 22 to 65 years
- Conditions the study is for
- Obesity (Disorder)
- 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
- 16 participants
- Where
- 1 siteUnited States
- Study dates
- 21 Apr 2025to 1 Sep 2026
- Phase
- Interventional
- 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 22 to 65 years
- All sexes
- No healthy volunteers
- 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 Baton Rouge, Louisiana or surrounding area
- 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
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
- 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
- Diagnosis or family history of sickle cell anemia/trait
Show all 13Show fewer
- 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.
United States1 site
Pennington Biomedical Research Center
Baton Rouge, Louisiana, 70808
About this study
Official title: Effects of Energy Restriction and Intermittent Hypoxia on Iron Absorption in Obesity
Declines in iron status are common in those with obesity and may be due to obesity-related chronic inflammation; however, the effects of reducing inflammation following diet-induced weight loss on iron metabolism are poorly understood. Low environmental oxygen exposure increases dietary iron absorption and availability to supply iron for erythropoiesis but has not yet been tested in the context of weight loss. This study is designed to investigate diet-induced weight loss (inflammation reduction) and overnight low oxygen exposure (erythropoiesis stimulating agent) as strategies to improve dietary iron absorption in obesity.
Read the detailed description
Those with obesity are at increased risk for iron deficiency, which can worsen obesity-related comorbidities and add considerably to national health-care budgets. Declines in iron status in those with obesity may be due to adiposity-related inflammation. Adipokines, such as interleukin 6, increase hepcidin, an iron regulatory hormone secreted by the liver that functions to reduce iron absorption and iron availability. Elevated hepcidin and reduced dietary iron absorption may explain why those with obesity are more susceptible to iron deficiency and more resistant to treatment with iron supplements. However, the effects of reducing inflammation on iron absorption in those with obesity are poorly understood. In addition, low environmental oxygen exposure may be an alternative to optimize iron metabolism in obesity since hypoxia stimulates the synthesis of erythropoietin, which strongly suppresses hepcidin and increases iron absorption. The proposed study aims to capitalize on the ongoing Low Oxygen and Weight Status (LOWS) randomized, double-blind, parallel-arm, controlled-feeding trial (R01DK127162; Berryman) to understand the mechanism by which obesity increases risk for iron deficiency and potential countermeasures. In LOWS, adults with obesity are randomized to 8 weeks of controlled-feeding energy restriction (-500 kcal/day) plus intermittent exposure to normobaric hypoxia (8 h/night, 15% FiO2) or normoxia (8 h/night, 21% FiO2) using a commercially available, in-home tent system. This study aims at assessing dietary iron absorption at baseline and following 8 weeks of energy restriction in normoxia or intermittent hypoxia. Results of this project will serve as a foundation to the development of interventions to prevent and treat declines in iron status in obesity.
- Conditions
- Obesity (Disorder)
- Being tested
- Normobaric hypoxia (NH), Normobaric normoxia (NN)
- Keywords
- Body weight, Normobaric hypoxia, Negative energy balance, Energy intake, Energy expenditure, Iron absorption, Iron metabolism
- 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 iron absorption
Fractional iron absorption will be measured during the baseline weight maintenance phase (day -7) and at the end of the study (day 42). Change in fractional iron absorption will be calculated as: fractional iron absorption on day 42 - fractional iron absorption on day -7.
Measured: 7 weeks
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted21 Apr 2026
- Study start21 Apr 2025
- Primary completion1 Sep 2026
- Study completion1 Sep 2026
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 Obesity (Disorder)Studies 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
- 16 participants (actual)
Sponsor and investigators
- Lead sponsor
- Pennington Biomedical Research Center
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
- Investigators
- Camila Weschenfelder, PhD, Principal investigator, Pennington Biomedical Research Center
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07542873
- Sponsor's protocol ID
- 2022-046-PBRC
- Other IDs
- U24DK132740
- Acronym
- LOWS-IRON
- Status last verified
- Apr 2026
- First submitted
- 14 Apr 2026
- Last updated
- 5 Oct 2026
- Results posted
- No
- Data monitoring committee
- Yes
- 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 5 Oct 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Effects of Energy Restriction and Intermittent Hypoxia on Iron Absorption in Obesity
- ClinicalTrials.gov ID
- NCT07542873
- Acronym / sponsor ID
- LOWS-IRON / 2022-046-PBRC
- Conditions
- Obesity (Disorder)
- Keywords
- Body weight, Normobaric hypoxia, Negative energy balance, Energy intake, Energy expenditure, Iron absorption, Iron metabolism
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 16 participants (actual)
- Lead sponsor
- Pennington Biomedical Research CenterUniversity, hospital or other
- Collaborators
- National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
- Study start
- 21 Apr 2025 (actual)
- Primary completion
- 1 Sep 2026 (actual)
- Study completion
- 1 Sep 2026 (actual)
- First posted
- 21 Apr 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Declines in iron status are common in those with obesity and may be due to obesity-related chronic inflammation; however, the effects of reducing inflammation following diet-induced weight loss on iron metabolism are poorly understood. Low environmental oxygen exposure increases dietary iron absorption and availability to supply iron for erythropoiesis but has not yet been tested in the context of weight loss. This study is designed to investigate diet-induced weight loss (inflammation reduction) and overnight low oxygen exposure (erythropoiesis stimulating agent) as strategies to improve dietary iron absorption in obesity.
Detailed description
Those with obesity are at increased risk for iron deficiency, which can worsen obesity-related comorbidities and add considerably to national health-care budgets. Declines in iron status in those with obesity may be due to adiposity-related inflammation. Adipokines, such as interleukin 6, increase hepcidin, an iron regulatory hormone secreted by the liver that functions to reduce iron absorption and iron availability. Elevated hepcidin and reduced dietary iron absorption may explain why those with obesity are more susceptible to iron deficiency and more resistant to treatment with iron supplements. However, the effects of reducing inflammation on iron absorption in those with obesity are poorly understood. In addition, low environmental oxygen exposure may be an alternative to optimize iron metabolism in obesity since hypoxia stimulates the synthesis of erythropoietin, which strongly suppresses hepcidin and increases iron absorption. The proposed study aims to capitalize on the ongoing Low Oxygen and Weight Status (LOWS) randomized, double-blind, parallel-arm, controlled-feeding trial (R01DK127162; Berryman) to understand the mechanism by which obesity increases risk for iron deficiency and potential countermeasures. In LOWS, adults with obesity are randomized to 8 weeks of controlled-feeding energy restriction (-500 kcal/day) plus intermittent exposure to normobaric hypoxia (8 h/night, 15% FiO2) or normoxia (8 h/night, 21% FiO2) using a commercially available, in-home tent system. This study aims at assessing dietary iron absorption at baseline and following 8 weeks of energy restriction in normoxia or intermittent hypoxia. Results of this project will serve as a foundation to the development of interventions to prevent and treat declines in iron status in 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
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (6 listed)
- Obese (BMI between 30-39.9 kg/m2)
- Born at altitudes below 2,100 meters (~7,000 feet)
- Currently residing in Baton Rouge, Louisiana or surrounding area
- 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.
Key exclusion criteria (13 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
- 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
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 iron absorption
Time frame: 7 weeks
Fractional iron absorption will be measured during the baseline weight maintenance phase (day -7) and at the end of the study (day 42). Change in fractional iron absorption will be calculated as: fractional iron absorption on day 42 - fractional iron absorption on day -7.
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 5 Oct 2026.
- Background: 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. This study is not recruiting at the moment.
Camila Weschenfelder, 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?
A study testing Normobaric hypoxia (NH) and Normobaric normoxia (NN) in people with Obesity (Disorder), 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 6 inclusion and 13 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 5 Oct 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in 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?
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?
Change in iron absorption (time frame: 7 weeks). 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 NCT07542873, 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 5 Oct 2026; AzTrials last refreshed its copy on 6 Nov 2026.