Energy Balance of Canadian Armed Forces Personnel during an Arctic-Like Field Training Exercise.

Mavra Ahmed,Elliot Desilets,Mary L’Abbé,Peter J Jones,Ira Jacobs,Ingrid Smith,Wendy Sullivan-Kwantes,Len Goodman,Iva Mandic

doi:10.3390/nu12061638

Abstract

Operating in temperature extremes frequently leads to a discrepancy in energy balance. Investigating the effects of operating in extreme cold temperatures on metabolic requirements has not been well described in Canadian Armed Forces (CAF) personnel. The objective was to accurately assess energy deficits using the “gold standard” methodology for measuring energy intake (EI) and energy expenditure (EE). Nutritional intake of a convenience sample of 10 CAF Class A Reservists, completing a basic military qualification (land) course under winter weather conditions, was assessed using the daily measured food intake/food waste collections. EE was measured by the doubly-labelled water method. Average EI was 2377 ± 1144 kcal/day, which was below the EE (4917 ± 693 kcal/day), despite having ~5685 kcal available in the field rations. A significant body weight loss of 2.7% was associated with the average daily energy deficit of 2539 ± 1396 kcal. As a result, participants demonstrated voluntary anorexia. Such results may have important implications for the impairment of performance and health under longer duration operations.

Highlights

During field training or operations, energy expenditures can range from less than 6000 to~10,000 kilocalories per day in different environmental conditions because of extended periods of physically demanding activities with limited sleep or rest [1,2,3]
During the 5-day study period, body mass was significantly reduced by 2.7% (−2.1 ± 1.1 kg) and body mass index (BMI) was significantly reduced by 3.0% (−0.8 ± 0.4 kg/m2 ) (p < 0.05)
The present results indicate, in a convenient sample of Canadian Armed Forces (CAF) Reservists, low energy and nutrient intakes coupled with a high energy expenditure, resulting in a significant loss (2.7%) of total body mass and a 4% decrease in body fat percentage after the 5-day training exercise

Summary

Introduction

~10,000 kilocalories (kcal) per day in different environmental conditions because of extended periods of physically demanding activities with limited sleep or rest [1,2,3]. These increases in energy expenditure are aggravated by extreme environmental temperatures [1,4,5]. In addition to the standard food allowances, incremental allowances may be provided under conditions when it is suspected that standard allowances may be insufficient to fuel the energy demands of metabolically challenging operations under environmental extremes [6,16,17]

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Discussion

Conclusion