The goal of this clinical trial is to investigate the effects of acute passive continuous hypoxemia (simulated high-altitude at rest) on appetite and energy intake in healthy young female adults. The main questions it aims to answer are: * Does six hours of simulated high-altitude (5000 meters) reduce scores of subjective appetite and energy intake? * Do changes in appetite and energy intake persist in the hours following the end of hypoxic exposure? Researchers will compare the effects of simulated high-altitude to a control normoxia (sea-level) condition to see if exposure to low oxygen levels independently affect appetite and energy intake. Participants will: * Visit the laboratory for a preliminary screening session to assess eligibility. * Undergo two randomized, single-blind, experimental sessions consisting of six hours of passive exposure to normoxia or hypoxia in a climate-controlled chamber. * Consume foods provided from a curated list, served in ad libitum quantities, after leaving the laboratory to assess post-exposure energy intake.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
SINGLE
Enrollment
12
Participants will undergo a 6-hour passive exposure to normoxia in a climate-controlled environmental chamber maintained at 22°C with 30% relative humidity. They will remain in a fasted state throughout the exposure period.
Participants will undergo a 6-hour passive exposure to a simulated altitude of 5000 meters above sea-level in a climate-controlled environmental chamber maintained at 22°C with 30% relative humidity. They will remain in a fasted state throughout the exposure period.
Behavioural and Metabolic Research Unit, School of Human Kinetics, Faculty of Health Sciences, University of Ottawa
Ottawa, Ontario, Canada
Change from baseline in desire to eat
Scores of subjective desire to eat, measured using visual analog scales. Measurements are performed upon arrival at the laboratory (baseline), hourly during the exposure, immediately after a 30-minute ad libitum buffet, immediately before bedtime, and 24 hours after the baseline measurement.
Time frame: Baseline and 6 hours; Baseline and 24 hours
Heart rate
Measured continuously throughout the exposure.
Time frame: 6 hours
Oxyhemoglobin saturation
Measured continuously throughout the exposure.
Time frame: 6 hours
Change from baseline in hunger
Scores of subjective hunger, measured using visual analog scales. Measurements are performed upon arrival at the laboratory (baseline), hourly during the exposure, immediately after a 30-minute ad libitum buffet, immediately before bedtime, and 24 hours after the baseline measurement.
Time frame: Baseline and 6 hours; Baseline and 24 hours
Systolic blood pressure
Measured upon arrival at the laboratory (baseline), hourly during the exposure, and immediately after eating.
Time frame: 6 hours
Change from baseline in fullness
Scores of subjective fullness, measured using visual analog scales. Measurements are performed upon arrival at the laboratory (baseline), hourly during the exposure, immediately after a 30-minute ad libitum buffet, immediately before bedtime, and 24 hours after the baseline measurement.
Time frame: Baseline and 6 hours; Baseline and 24 hours
Diastolic blood pressure
Measured upon arrival at the laboratory (baseline), hourly during the exposure, and immediately after eating.
Time frame: 6 hours
Change from baseline in prospective food consumption
Scores of subjective prospective food consumption, measured using visual analog scales. Measurements are performed upon arrival at the laboratory (baseline), hourly during the exposure, immediately after a 30-minute ad libitum buffet, immediately before bedtime, and 24 hours after the baseline measurement.
Time frame: Baseline and 6 hours; Baseline and 24 hours
Lake Louise Acute Mountain Sickness Score
Peak score on the Lake Louise Acute Mountain Sickness questionnaire, measured upon arrival at the laboratory (baseline), hourly during the exposure, and immediately after eating.
Time frame: 6 hours
Energy intake immediately after 6 hours of exposure (buffet)
Energy intake in the laboratory during a 30-minute ad libitum buffet immediately after 6 hours of exposure, administered using a validated food menu (McNeil, 2012) and analyzed using the Food Processor SQL from ESHA Research, Inc.
Time frame: Hour 6 of exposure
Fluid consumption during exposure
Average hourly fluid consumption calculated by weighing participant water intake at the start and end of each hour of exposure (normalized to the exposure duration).
Time frame: 6 hours
Energy intake post-buffet
Energy intake outside the laboratory between end-buffet and bedtime, administered using a validated food menu (McNeil, 2012) and analyzed using the Food Processor SQL from ESHA Research, Inc.
Time frame: 6.5 hours of exposure and 24 hours
Change from baseline in explicit liking using the LFPQ
Explicit liking will be measured using the Leeds Food Preference Questionnaire. Measurements will be taken upon arrival at the laboratory (baseline), following 5 hours of exposure, and after a 30-min ad libitum buffet.
Time frame: Baseline and 6.5 hours of exposure
Change from baseline in explicit wanting using the LFPQ
Explicit wanting will be measured using the Leeds Food Preference Questionnaire. Measurements will be taken upon arrival at the laboratory (baseline), following 5 hours of exposure, and after a 30-min ad libitum buffet.
Time frame: Baseline and 6.5 hours of exposure
Change from baseline in implicit wanting using the LFPQ
Implicit wanting will be measured using the Leeds Food Preference Questionnaire. Measurements will be taken upon arrival at the laboratory (baseline), following 5 hours of exposure, and after a 30-min ad libitum buffet.
Time frame: Baseline and 6.5 hours of exposure
Change from baseline in olfaction
Olfaction will be measured using the Sniffin' Sticks (Burghart Instruments, Wedel, Germany), a 3-test battery of odorized markers that measure odor detection threshold, odor discrimination, and odor identification. Measurements will be performed upon arrival at the laboratory (baseline) and following 4 hours of exposure.
Time frame: Baseline and Hour 4 of exposure
Change from baseline in gustation
Olfaction will be measured using Taste Strips (Burghart Instruments, Wedel, Germany). Measurements will be performed upon arrival at the laboratory (baseline) and following 4 hours of exposure.
Time frame: Baseline and Hour 4 of exposure
Change from baseline in resting energy expenditure
Resting energy expenditure will be measured via indirect calorimetry upon arrival at the laboratory (baseline) and following 5 hours of exposure.
Time frame: Baseline and Hour 5 of exposure
Change from baseline in respiratory exchange ratio
Respiratory exchange ratio will be measured via indirect calorimetry upon arrival at the laboratory (baseline) and following 5 hours of exposure.
Time frame: Baseline and Hour 5 of exposure
Change from baseline in plasma glucose concentrations
Plasma glucose concentrations will be measured via colorimetric assays from venous blood samples collected upon arrival at the laboratory (baseline) and hourly during the exposure (i.e., 0 or baseline, 60, 120, 180, 240, 300, and 360 minutes).
Time frame: 6 hours
Change from baseline in plasma insulin concentrations
Plasma insulin concentrations will be measured via colorimetric assays from venous blood samples collected upon arrival at the laboratory (baseline) and hourly during the exposure (i.e., 0 or baseline, 60, 120, 180, 240, 300, and 360 minutes).
Time frame: 6 hours
Change from baseline in plasma non-esterified fatty acid concentrations
Plasma non-esterified fatty acid concentrations will be measured via colorimetric assays from venous blood samples collected upon arrival at the laboratory (baseline) and hourly during the exposure (i.e., 0 or baseline, 60, 120, 180, 240, 300, and 360 minutes).
Time frame: 6 hours
Change from baseline in plasma triglyceride concentrations
Plasma triglyceride concentrations will be measured via colorimetric assays from venous blood samples collected upon arrival at the laboratory (baseline) and hourly during the exposure (i.e., 0 or baseline, 60, 120, 180, 240, 300, and 360 minutes).
Time frame: 6 hours
Change from baseline in plasma beta-hydroxybutyrate concentrations
Plasma beta-hydroxybutyrate concentrations will be measured via colorimetric assays from venous blood samples collected upon arrival at the laboratory (baseline) and hourly during the exposure (i.e., 0 or baseline, 60, 120, 180, 240, 300, and 360 minutes).
Time frame: 6 hours
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