Energy and Macronutrient Metabolism in High Performance Athletes (Oral Session 20)

(OR20-03-25) Higher Fat Combat Rations Minimize Energy Deficits During a 5-Day Military Training Exercise

Tuesday, June 3, 2025

8:56 AM – 9:06 AM ET

Location: S230 CD

Presenting Author(s)

M. Alan Dawson, PhD

Military Deputy Chief, Military Nutrition Division
U.S. Army Research Institute of Environmental Medicine
Hopkinton, Massachusetts, United States

Disclosure(s): No relevant financial relationship(s) with ineligible companies to disclose.

Co-Author(s)

AH

Adrienne Hatch-McChesney, MS, RD, CSSD (she/her/hers)

Research Dietitian
U.S. Army Research Institute of Environmental Medicine
Natick, Massachusetts, United States
TN

Tshinanne V. Ndou

US Army Combat Capabilities Development Command Soldier Center, United States
JM

Julie McNiff

Combat Feeding Directorate, United States
EH

Emily E. Howard, PhD

Nutrition Physiologist
US Army Research Institute of Environmental Medicine
Natick, Massachusetts, United States
J. Philip Karl, PhD, RD (he/him/his)

Nutritional Physiologist
U.S. Army Research Institute of Environmental Medicine
Roslindale, Massachusetts, United States
LM

Lee M. Margolis, PhD, RD

U.S. Army Research Institute of Environmental Medicine
Tracey J. Smith, PhD, RD

Deputy Chief/Nutrition Scientist
U.S. Army Research Institute of Environmental Medicine
Natick, Massachusetts, United States
JM

James P. McClung

U.S. Army Research Institute of Environmental Medicine
JJ

Julianna M. Jayne

Defense Centers for Public Health - Aberdeen, Maryland, United States

Objectives: Military personnel often experience energy deficits during short-duration training and operations due to high daily energy expenditures and logistical constraints that limit food availability. One approach to enhance energy intake while minimizing the weight of carried provisions during military training is to increase the fat content of rations. The Close Combat Assault Ration (CCAR) has been developed as a higher fat, lower volume alternative to address these challenges for scenarios lasting less than seven days. However, the effects of consuming the CCAR during short-term military training, compared to the standard issued First Strike Ration (FSR), had not been previously assessed. This study aimed to determine the effects of consuming the CCAR, compared to the FSR, during a 5-day field training exercise (FTX) on energy intake, energy balance and physical performance.

Methods: Active-duty servicemembers participating in this parallel, single-blinded trial were randomized to consume either one CCAR (n=29; 2843kcal, 84g protein, 333g carbohydrate, 128g fat) or one FSR (n=28; 2809kcal, 87g protein, 417g carbohydrate, 92g fat) each day as their sole source of nutrition during the FTX. Doubly-labeled water was used to measure energy expenditure. Energy intake was calculated by measuring consumption of provided rations. To assess physical performance, participants completed a maximum vertical jump, a 300-yard shuttle sprint, and a lower-body strength pull before and after the FTX.

Results: Energy expenditure was similar (p=0.68) between CCAR (3245±238kcal/d) and FSR (3276±317kcal/d), but energy intake was higher in CCAR compared to FSR (2194±539 kcal/d and 1914±611 kcal/d, respectively, p=0.001) resulting in attenuated energy deficits (-32±12% vs. -42±11%, respectively, p=0.003). Lower-body power, 300-yard shuttle sprint time, and peak pull force were not different between groups (p-interaction≥0.05).

Conclusions: Higher-fat rations can be effective as a short-term nutritional strategy to mitigate energy deficits when lower weight and volume rations are required, without affecting physical performance.

Funding Sources: Supported by U.S. Army Medical Research and Development Command and the U.S. Army Combat Capabilities Development Command Soldier Center.

DISCLAIMER: Authors’ views do not reflect official DoD or Army policy.