Effects of Overnight Low Oxygen Exposure on Energy Balance

Effects of an Overnight, 8-hour Low Oxygen Exposure on Resting Energy Expenditure and Appetite: a Pilot Study

This research study will evaluate changes in resting metabolic rate, appetite, and heart rate variability following overnight exposure (8 h/night) to normobaric hypoxia (NH) or normobaric normoxic (NN). In randomized order, participants will sleep one night in NH conditions (~15% oxygen; achieved with nitrogen dilution, equivalent to ~8500 feet elevation) and another night in NN (control) conditions (~20% oxygen; achieved with nitrogen dilution, equivalent to ~1000 feet elevation).

Study Overview

• Status: Completed
• Conditions: Heart Rate Variability; Appetite; Resting Metabolic Rate
• Intervention / Treatment: Device: Normobaric Hypoxia; Device: Normobaric Normoxia

Detailed Description

Weight loss is a common factor reported in lowlanders traveling to high altitudes. Although the exact cause is unknown, studies have shown that weight loss at high altitude is associated with the amount of time and severity of the altitude exposure. Upon arrival to high altitude (≥ 5000 feet), numerous physiological adaptations occur that may promote weight loss, such as increased energy expenditure and reduced appetite. The breadth of current altitude research is limited by the logistical and monetary constraints of traveling to remote locations or access to an altitude chamber. A more logistically feasible alternative is the simulation of low oxygen conditions at sea level, using a commercially available tent and generator system to reduce ambient oxygen concentrations. The current research study will evaluate changes in resting metabolic rate, appetite, and heart rate variability following overnight exposure (8 h/night) to normobaric hypoxia (NH) or normobaric normoxic (NN). In randomized order, participants will sleep one night in NH conditions (~15% oxygen; achieved with nitrogen dilution, equivalent to ~8500 feet elevation) and another night in NN (control) conditions (~20% oxygen; achieved with nitrogen dilution, equivalent to ~1000 feet elevation). In the morning, following NH or NN exposure, resting metabolic rate will be measured using indirect calorimetry, appetite using an ad libitum buffet meal protocol, and heart rate variability by electrocardiogram. It is hypothesized that exposure to overnight NH will result in increased resting metabolic rate, decreased appetite, and decreased heart rate variability.

• Study Type: Interventional
• Enrollment (Actual): 20
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • Florida
    • Tallahassee, Florida, United States, 32306
      • Florida State University

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 20 years to 45 years (Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

Description

Inclusion Criteria:

• Men and women aged 20 - 45 years
• Body mass index between 18.5 - 24.5 kg/m2
• Born at altitudes less than 2,100 meters (~7,000 feet)
• Currently residing in Tallahassee, Florida or the surrounding area
• Not taking any medication(s) that interfere with metabolism or oxygen delivery/transport for four weeks before 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 spend two overnight visits on the Florida State University campus.

Exclusion Criteria:

• 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 two months
• Metabolic or cardiovascular abnormalities, gastrointestinal disorders, or any condition that interferes with metabolism or oxygen delivery/transport (e.g., kidney disease, diabetes, cardiovascular disease, etc.)
• Prior diagnosis of apnea or other sleeping disorders
• Prior diagnosis of high-altitude pulmonary edema or high-altitude cerebral edema
• Prior diagnosis of anemia or sickle cell anemia/trait
• Present condition of alcoholism, anabolic steroid, 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 six months.
• Allergies or intolerance to foods included in the standardized or ad libitum meal (e.g., lactose intolerance/milk allergy)

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Normobaric Hypoxia (NH); Overnight exposure (8 hours) 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).	Device: Normobaric Hypoxia; Low oxygen exposure to mimic ~8500 feet elevation.; Device: Normobaric Normoxia; Normal oxygen exposure to mimic ~1000 feet elevation (sham comparator).
Sham Comparator: Normobaric Normoxia (NN); Overnight exposure (8 hours) to NN conditions (~20% oxygen; achieved with nitrogen dilution, equivalent to ~1000 feet elevation) using a commercially available tent and generator system (Hypoxico, Inc., New York, NY).	Device: Normobaric Hypoxia; Low oxygen exposure to mimic ~8500 feet elevation.; Device: Normobaric Normoxia; Normal oxygen exposure to mimic ~1000 feet elevation (sham comparator).

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Resting metabolic rate (kcal/d) following exposure to NH or NN conditions	Resting metabolic rate will be accessed using indirect calorimetry (TrueOne 2400, Parvo Medics, Salt Lake City, UT) following 8 hours of overnight exposure to NH or NN.	8 hours

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Objective appetite following exposure to NH or NN conditions	Objective appetite will be assessed by measuring total energy intake during an ad libitum buffet-style meal provided to participants following 8 hours of overnight exposure to NH or NN.	8 hours
Food preferences following exposure to NH or NN conditions	Food preferences will be assessed by measuring macronutrient intake during an ad libitum buffet-style meal provided to participants following 8 hours of overnight exposure to NH or NN.	8 hours
Fasting and postprandial hunger following exposure to NH or NN conditions	Measures will be assessed before and after the ad-libitum buffet meal using visual analog scales following 8 hours of overnight exposure to NH or NN.	Hunger will be measured pre-meal (0 min), immediately post-meal, and at 15, 30, 45, 60, 90, and 120 min following 8 hours of NH or NN exposure
Fasting and postprandial satiety following exposure to NH or NN conditions	Measures will be assessed before and after the ad-libitum buffet meal using visual analog scales following 8 hours of overnight exposure to NH or NN.	Satiety will be measured pre-meal (0 min), immediately post-meal, and at 15, 30, 45, 60, 90, and 120 min following 8 hours of NH or NN exposure
Fasting and postprandial prospective food consumption following exposure to NH or NN conditions	Measures will be assessed before and after the ad-libitum buffet meal using visual analog scales following 8 hours of overnight exposure to NH or NN.	Prospective food consumption will be measured pre-meal (0 min), immediately post-meal, and at 15, 30, 45, 60, 90, and 120 min following 8 hours of NH or NN exposure
Fasting and postprandial subjective appetite following exposure to NH or NN conditions	Measures will be assessed before and after the ad-libitum buffet meal using visual analog scales following 8 hours of overnight exposure to NH or NN.	Subjective appetite will be measured pre-meal (0 min), immediately post-meal, and at 15, 30, 45, 60, 90, and 120 min following 8 hours of NH or NN exposure
Energy intake following exposure to NH or NN conditions	Energy intake will be accessed using the Automated Self-Administered 24-Hour (ASA24®) Dietary Assessment Tool to complete dietary records for 2 days following 8 hours of overnight exposure to NH or NN.	8 hours
Macronutrient intake following exposure to NH or NN conditions	Macronutrient intake will be accessed using the Automated Self-Administered 24-Hour (ASA24®) Dietary Assessment Tool to complete dietary records for 2 days following 8 hours of overnight exposure to NH or NN.	8 hours
Heart rate variability following exposure to NH or NN conditions	Heart rate variability will be measured using a 3-lead electrocardiogram following 8 hours of overnight exposure to NH or NN.	8 hours
Prevalence of acute mountain sickness following exposure to NH or NN conditions	Prevalence of acute mountain sickness will be accessed using the Environmental Symptoms Questionnaire following 8 hours of overnight exposure to NH or NN.	8 hours
Severity of acute mountain sickness following exposure to NH or NN conditions	Severity of acute mountain sickness will be accessed using the Environmental Symptoms Questionnaire following 8 hours of overnight exposure to NH or NN.	8 hours
Continuous oxygen saturation during exposure to NH or NN	Oxygen saturation will be measured continuously using a finger pulse oximeter (PalmSAT® 2500, Nonin Medical, Inc., Plymouth, MN) during 8 hours of overnight exposure to NH or NN.	8 hours
Sleep quality following exposure to NH or NN conditions	Sleep quality will be measured by the Pittsburgh Sleep Quality Index following 8 hours of overnight exposure to NH or NN.	8 hours

Collaborators and Investigators

• Sponsor: Florida State University
• Investigators: Principal Investigator: Claire E Berryman, Ph.D., Department of Nutrition, Food, and Exercise Science at Florida State University.

Study record dates

Study Major Dates

• Study Start (Actual): December 11, 2019
• Primary Completion (Actual): October 2, 2021
• Study Completion (Actual): October 2, 2021

Study Registration Dates

• First Submitted: October 26, 2019
• First Submitted That Met QC Criteria: November 2, 2019
• First Posted (Actual): November 5, 2019

Study Record Updates

• Last Update Posted (Actual): November 29, 2021
• Last Update Submitted That Met QC Criteria: November 26, 2021
• Last Verified: November 1, 2021

More Information

Terms related to this study

• Keywords: Energy balance; Metabolic adaptations; High altitude
• Other Study ID Numbers: STUDY00000184

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: No

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No