The goal of this randomized clinical trial is to determine the effects of consuming the Close Combat Assault Ration (CCAR) compared to the First Strike Ration (FSR) during a 7-day strenuous military training on energy intake and energy balance in healthy, Active Duty Warfighters.

The main questions it aims to answer are:

• Will consuming the CCAR result in lower energy intake or energy balance compared to consumption of the FSR?
• Will consuming the CCAR result in lower lower body strength or anaerobic power compared to consuming the FSR?
• Will those consuming the CCAR report lower ration acceptability or greater gastrointestinal side effects compared to those consuming the FSR?

Participants will be asked to consume either the CCAR or FSR as the sole nutrition source during a 7-day field training exercise (FTX). The vertical jump test, running-based anaerobic sprint test, and lower-body strength pull will be conducted pre and post the 7-day FTX to assess physical performance. Energy expenditure and intake will be measured by the doubly-labelled water method and dietary logs, respectively. Surveys will be completed to assess ration acceptability and gastrointestinal symptoms.

Researchers will compare the CCAR and FSR groups to see if their consumption impacted energy intake, energy balance, physical performance, ration acceptance, or gastrointestinal side effects.

Army modernization priorities have identified the need to build the "capability to sustain multiple Brigade Combat Teams for up to seven days without periodic resupply to support semi-independent operations". To address this challenge and meet modernization requirements, ration developers from the Combat Feeding Division (CFD), Soldier Sustainment Directorate, Combat Capabilities Development Command - Soldier Center (DEVCOM-SC) developed the next generation ration, the Close Combat Assault Ration (CCAR). The CCAR is produced using novel food processing techniques that reduce weight and volume by removing air and water and increase the energy density by increasing the relative fat content. The result is a lightweight, low volume, energy-dense, shelf-stable, daily combat assault ration that provides Warfighters with meals that can be consumed while on the move, requiring no heating and little to no field preparation.

The ration will provide approximately 2800 kcals/day (47% carbohydrate, 12% protein, 41% fat) and includes a greater distribution of energy from fat to enable a smaller logistic footprint than the First Strike Ration (FSR, 2800 kcals/d; 58% carbohydrate, 12% protein, 30% fat).

This proposed project will evaluate the CCAR relative to the current recommended materiel solution (i.e., the FSR) in a field setting that approximates the operational conditions under which the ration will be consumed. Specifically, the proposed effort will compare energy intake, energy balance, physical performance, appetite, ration acceptability, and gastrointestinal responses in military personnel randomized to consume the CCAR or FSR in a multi-day training environment.

Participants will be randomized to consume the CCAR or FSR during a 7-day field training exercise. Physical performance will be assessed PRE and POST by the Running-Based Anaerobic Sprint Test, lower-body strength pull, and vertical jump. A subset of participants will consume doubly-labeled water and provide urine samples throughout the study period to measure energy expenditure. Appetite, ration acceptability, and gastrointestinal symptoms will be assessed by daily surveys. Energy intake will be measured by review of uneaten ration products and daily logs.

Inclusion Criteria:

• Active-duty male or female military personnel who are actively participating in the 7-day strenuous military training exercise.
• Willing to consume only foods/beverages provided by study staff during the training exercise, except for coffee and water.

Exclusion Criteria:

• Any injury or health condition limiting full participation in the 7-day Field Training Exercise.
• Any food allergy, lactose intolerance, or vegetarian practices.
• Not willing to participate in all study procedures.