Supplemental bar energy or EAA density did not affect whole-body protein balance during Arctic military training when soldiers achieved high protein intakes (>1.6 g/kg/d) and modest energy deficits (~24%).
Key Findings
Results
Energy expenditure, energy intake, and energy deficits were not significantly different between the three supplemental bar groups during 8-day Arctic military training.
Energy expenditure was 5341 ± 674 kcal/d across all groups
Energy intake was 4045 ± 738 kcal/d across all groups
Energy deficits averaged -1257 ± 599 kcal/d, representing a 24 ± 11% deficit
Differences between groups were not significant (P > 0.05)
All participants received 3 standard rations plus 4 supplemental bars daily
Results
Protein intake exceeded 1.6 g/kg/d in all three treatment groups throughout the Arctic training exercise.
This threshold was met across EAA-Dense (n = 27), EN-Dense (n = 22), and CON (n = 19) groups
The study used a randomized, controlled trial design
Participants were Norwegian soldiers in an 8-day Arctic training exercise
Dietary intake was measured daily throughout the exercise
Results
Whole-body protein flux, synthesis, breakdown, and net balance all changed significantly from before to after training, independent of treatment group.
Protein flux increased from PRE 1.21 ± 0.23 to POST 1.34 ± 0.36 g N/kg/d (P < 0.05)
Protein synthesis increased from PRE 3.46 ± 2.06 to POST 5.43 ± 2.86 g/kg/d (P < 0.05)
Protein breakdown increased from PRE 6.26 ± 1.35 to POST 6.95 ± 2.12 g/kg/d (P < 0.05)
Net protein balance improved from PRE -2.80 ± 1.61 to POST -1.51 ± 1.60 g/kg/d (P < 0.05)
Measurements were made overnight before and after training using 15N-alanine stable isotope methodology
Results
Neither EAA-dense nor energy-dense supplemental bars preserved whole-body protein balance more effectively than high-carbohydrate control bars during Arctic military training.
The three supplemental bar conditions were EAA-Dense, EN-Dense (energy-dense), and CON (high-carbohydrate control)
PRE to POST changes in protein flux, synthesis, breakdown, and net balance occurred independent of treatment
The authors conclude that 'protein utilization remains independent of the macronutrient formulation of supplemental bars during military training scenarios with high protein intakes and moderate energy deficits'
Energy expenditure was measured using doubly labeled water
Results
Net protein balance remained negative after training but improved significantly, suggesting that high protein intake with moderate energy deficit during Arctic military training does not prevent but may attenuate protein losses.
Net balance was negative at both time points: PRE -2.80 ± 1.61 g/kg/d and POST -1.51 ± 1.60 g/kg/d
Both protein synthesis and breakdown increased POST training, indicating elevated protein turnover
The improvement in net balance occurred despite ongoing energy deficit
The authors note that energy deficit severity and dietary protein intake are 'primary determinants of negative whole-body protein balance during strenuous military training'
Background
The study was designed to test whether attenuating energy deficits with energy-dense foods or providing EAA-dense foods could preserve whole-body protein balance during cold-weather military training.
The trial was registered at clinicaltrials.gov as NCT05210205
68 Norwegian soldiers were enrolled and randomized across three groups
The exercise lasted 8 days in Arctic conditions
Low-volume energy-dense foods were proposed as a means to 'promote energy intake' in operational settings where food volume is constrained
What This Means
This research examined whether giving soldiers special food bars — either packed with essential amino acids (the building blocks of protein) or dense in calories — could better maintain muscle protein during an intense 8-day Arctic military training exercise compared to standard high-carbohydrate bars. Norwegian soldiers were randomly assigned to receive one of the three types of supplemental bars in addition to their standard military rations each day. The researchers measured how much energy soldiers burned, how much they ate, and used specialized isotope techniques to track protein building and breakdown in the body before and after training.
The study found that regardless of which type of bar soldiers received, their bodies responded to the training in the same way: protein synthesis and breakdown both increased after training, and net protein balance — the difference between how much protein the body builds versus breaks down — improved slightly but remained negative in all groups. Importantly, the macronutrient makeup of the supplemental bars (whether amino acid-rich, calorie-dense, or carbohydrate-heavy) made no significant difference to these outcomes. All three groups ended up eating similar amounts of calories and protein, with a moderate energy deficit of about 24% below what they expended.
This research suggests that when soldiers are already consuming adequate protein (more than 1.6 grams per kilogram of body weight per day) and facing only moderate energy deficits, the specific nutrient composition of supplemental food bars does not meaningfully change how the body handles protein. For military planners and nutritionists, this implies that under these conditions, the precise formulation of supplemental rations may matter less than ensuring overall protein and energy intake reach sufficient levels. However, the findings may not apply to situations with more severe energy deficits or lower protein intakes.
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Howard E, Teien H, Hatch-McChesney A, Robillard J, Murphy N, Carrigan C, et al.. (2026). Whole-Body Protein Balance during Arctic Military Training Is Unaffected by Dietary Essential Amino Acid or Energy Density.. The Journal of nutrition. https://doi.org/10.1016/j.tjnut.2026.101514