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

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.