Soldiers commonly lose muscle mass during training and combat operations that produce large energy deficits (i.e., calories burned > calories consumed). Developing new combat ration products that increase energy intake (i.e., energy dense foods) or the amount and quality of protein consumed (i.e., essential amino acid [EAA] content) may prevent muscle breakdown and stimulate muscle repair and muscle maintenance during unavoidable energy deficit. The primary objective of this study is to determine the effects of prototype recovery food products that are energy dense or that provide increased amounts of EAAs (anabolic component of dietary protein) on energy balance, whole-body net protein balance, and indices of physiological status during strenuous winter military training.

Up to 96 Norwegian Soldiers participating in a winter training exercise at the Garrison in Sør-Varanger (GSV) will be enrolled in an approximately 11-day, randomized controlled study. Participants will be randomly assigned at the beginning of the training exercise to groups provided 3 Norwegian Army arctic combat rations and approximately 1500 supplemental calories from food products with increased energy density (EN-DENSE), increased essential amino acids (EAA), or low energy density (CONTROL) each day. Participants will be instructed to consume all of the supplemental food products provided to them and consume the arctic combat rations ad libitum. The effect of consuming EN-DENSE, EAA, or CONTROL food products during strenuous military training on physiological status and recovery will be assessed using dietary analysis, stable isotope methodologies, physical performance measures, gut health analyses, blood sampling, and questionnaires. This design will test the hypothesis that 1) EN-DENSE ration products will attenuate the energy deficit during the training, thereby limiting whole-body protein losses and decrements in physiological status; and 2) the protein-sparing benefit of EAA will limit whole-body protein loss regardless of the energy deficit.

Inclusion Criteria:

Male and female Norwegian Soldiers aged 18 years or older participating in the winter training exercise at the Garrison in Sør-Varanger.

Exclusion Criteria:

• Any injury or health condition limiting full participation in the training program.
• Allergies or intolerance to foods used in the study (including but not limited to lactose intolerance/milk allergy) or vegetarian practices.