(P12-39-26) Relationships Between Elevation of Residence and Energy Balance Components, Body Composition, and Cardiometabolic Health Among Active-Duty Soldiers

Objectives: Living at altitude is associated with a lower risk of developing overweight or obesity, likely from reduced arterial oxygen tension in the lower pressure environment. Acute altitude exposure reduces appetite and increases resting metabolic rate (RMR), but longer-term energy balance and cardiometabolic effects remain unclear. This study examined relationships between living at higher altitude and indicators of energy balance (RMR, energy intake [EI]), body composition, and cardiometabolic health (systolic/diastolic blood pressure [SBP/DBP], glycemic control) in active-duty Soldiers.

Methods: Data on RMR (indirect calorimetry), EI (24 h dietary recalls), body composition (bioelectric impedance), and cardiometabolic markers were collected from a representative sample of active-duty Soldiers at 5 Army installations from 2024-2026 as part of the Military Health and Nutrition Examination Study. Soldiers at Ft. Carson in Colorado Springs, CO (~1800 m; moderate altitude) were compared to Soldiers from 4 sea-level (≤175 m) installations. Associations between altitude of residence and RMR, EI, body composition, SBP/DBP, serum glucose and insulin concentrations, and the homeostatic model assessment of insulin resistance (HOMA-IR) were tested with linear regression. All models were adjusted for age and sex. The RMR model was also adjusted for lean body mass and mean outdoor temperature.

Results: A total of 525 Soldiers were living at sea-level (Male/Female = 397/127, age = 29.7 ±7.5 y, BMI = 28.0 ±4.3 kg/m²), and 123 Soldiers were living at altitude (M/F = 88/35, age = 29.6 ± 8.0 y, BMI = 28.0 ± 3.9 kg/m²). Compared to sea-level, living at altitude was associated with a higher RMR (197 kcal/d [95% CI: 106, 288]), higher DBP (3.5 mm Hg [1.8, 5.3]), lower glucose (-3.5 mg/dL [-5.3, -1.8]) and a trend towards lower body fat percentage (-1.6% [-3.2, 0.0], p = 0.052). Altitude was not associated with EI, other body composition, SBP, insulin, or HOMA-IR.

Conclusions: In active-duty Army Soldiers, living at altitude (1800 m) was associated with higher RMR and DBP but lower glucose compared to living at sea-level. Additional research is needed to identify how energy balance is maintained despite greater RMR while living at altitude and the potential cardiometabolic consequences.

Funding Sources: USAMRDC; views expressed are not official US Army, DoW, or government policy.