NATICK, Mass. (July 24, 2017) -- About two hours north of Oslo, in the bitter cold of Elverum, Norway, U.S. Army Research Institute of Environmental Medicine, or USARIEM, scientists partnered with the Norwegian Defence Material Agency to conduct an eating behavior field study in an effort to improve nutritional intake and military ration design for Soldiers operating in cold weather.Often, Soldiers can experience negative energy balance during cold-weather training when they cannot easily replace the calories they burn during rigorous physical activity. Pål Stenberg, commander of the Norwegian Defence Material Agency Catering branch and principal investigator of the Norway study, supported by Dr. Scott Montain, chief of USARIEM's Military Nutrition Division, or MND, and the Combat Feeding Directorate, or CFD, at the Natick Soldier Research, Development and Engineering Center, or NSRDEC, has been working to develop the next generation of Norway's cold-weather field rations in an effort to tackle this prevalent, yet complex, problem.Stenberg and Montain explained that negative energy balance in warfighters can be caused by a number of different factors, from environmental conditions to lack of time, physical or mental stress that can reduce appetite, how the ration tastes or how functional it is in the environment in which a Soldier is working."The food a warfighter chooses to discard might affect his or her ability to perform and fight," Stenberg said. "In just a few days, we have seen results of reduced muscle loss, especially from those individuals with a lean body mass. However, we would like to see our troops alert and ready with optimal performance at any time. Sufficient nutrition will provide optimal performance, both physically as well as cognitively.""Whether in Norway or in the U.S., undernutrition is something we almost always see in Soldiers during training," Montain said. "In arctic winter conditions, Soldiers can expend huge amounts of energy--up to 6,000 calories per day. This is more than double what a typical person in an office job would be burning in a day. Eating enough to meet this high energy demand, however, is difficult because Soldiers are eating as time permits and in difficult environmental conditions."While the Army has spent decades making field rations nutritious and safe, Montain and Stenberg know that part of the challenge is encouraging Soldiers to consume the much-needed nutrients despite having less time or energy in a high-stress environment. The two researchers noted that the amount of food on your plate, or (in a Soldier's case) in an unwrapped ration, could greatly influence how much you are actually going to eat."This study is a research cooperation between USARIEM, University of Oslo, and Norwegian Surgeon General command, and the purpose is to find out if troops will increase their daily intake by providing them with larger entrées for breakfast, lunch and dinner," Stenberg said."Typically, approximately 90 percent of the main entrées that are issued in individual field rations are consumed, making it a great target for an intervention designed to increase Soldier daily energy intake," Montain said.In March, MND researchers Anthony Karis and Susan McGraw, as well as Barbara Daley from CFD, traveled to Terningmoen, Norway, an Elverum training base for royal guardsman, to execute a four-day eating behavior study. They wanted to test if increasing the size or volume of the main entrée would increase the amount of energy Soldiers ate per meal, over the course of a day and over the four-day exercise. After measuring the height, weight and body fat of 57 Norwegian Soldiers, the researchers randomly divided the Soldiers into two groups.A control group received rations that contained normal amounts of food. The experimental group received rations with overfilled entrées that contained one-third more food."We wanted to see if the added size of the main entrée led to increased energy intake or if Soldiers compensated and changed their eating behavior by either eating only a portion of the larger entrée or by eating less of the other components in the ration," Karis said. "To test our idea, we tracked the fate of each of the food items they received."Since the Norwegian Army uses freeze-dried rations during cold weather, the two different-sized entrées looked very similar in size to each other when removed from the ration package. Soldiers had no clue how much food they had in their entrée until they had actually rehydrated the food. While the main entrées differed in size, the ration contents remained the same for both groups.The researchers instructed the study volunteers to fill out eating cards to record which components in the cold-weather rations they had eaten, how much of the food component they had consumed, and if they did not eat an item--why they left it uneaten. They went through the study volunteers' disposed cold-weather rations to verify that the food listed as eaten on the card was accurate. They also used visual estimation to verify the amount of the component that was actually consumed. By doing this, the researchers could better understand how entrée size influenced eating behavior.While the MND and CFD researchers collected data, it was business as usual for the Soldiers at Terningmoen. The Soldiers performed field marches, dug foxholes, and learned to set up guard and use a bayonet in 20- to 40-degree Fahrenheit weather.On the final day of the field study, the researchers took the Soldiers' final body composition measurements before flying home.Now back in the U.S., the researchers are diligently processing the data to determine if the larger entrée led to greater daily energy intake. They are continuing to collaborate with their Norwegian research partners in interpreting the data.The relationship between cold weather and Soldiers' nutrition and eating behavior is complex. The researchers realize there is much more to understand to create a military ration that is nutritious, tasty and easy to prepare in such an extreme environment. Karis said that these field studies in Norway are extremely important for the U.S. Army researchers because they allow them to see firsthand how the cold affects Soldiers' use of operational rations and the challenges it creates for sustaining health and performance. The information the two countries are gathering by working together is intended to provide their Soldiers with practical solutions when operating in extremely cold temperatures so they are healthy enough to continue performing their missions and training."Norway is basically the lead in cold weather survival because they operate in a cold, damp environment for most of the year, while the U.S. only faces winter for a few months out of the year," Karis said. "Yet, every military seems to have an issue with negative energy balance when out in the field in the cold. This is not just a unique issue for the United States. Canada, Norway and other countries that work in the cold have similar issues. This study was a perfect opportunity for USARIEM, NSRDEC and Norway to work together and learn what we can do to tackle persisting challenges in field feeding."