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11
Situational Influences on Food Intake

Edward S. Hirsch1 and F. Matthew Kramer

INTRODUCTION

If one were asked to describe a situation where eating was not likely to occur, the description would probably contain many elements of the battlefield. It is striking that the thorough nutritional surveys taken during World War II were virtually unanimous in reporting the absence of nutritional disease among troops when food supplies were adequate (Bean, 1946; Johnson and Kark, 1946; Youmans, 1955). These surveys also frequently found weight loss (Youmans, 1955). Consistent with these observations, surveys of troops during World War II found that 54 to 73 percent reported that they were hungry during combat (Webster and Johnson, 1945). More recent observations in the Falkland islands (McCaig and Gooderson, 1986) and a retrospective survey of U.S. Marines who had served in World War II, Korea, and Vietnam (Popper et al., 1989) indicated that during combat, troops reported eating considerably less than usual. The picture that emerges is that under combat conditions troops consume sufficient food to avoid frank nutritional disease but do not consume enough food to meet their energy needs, and some weight loss occurs.

THE UNDERCONSUMPTION PROBLEM

During the past 10 years, the full range of current military rations has been rigorously tested under various field and climatic conditions by the

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Edward S. Hirsch, U.S. Army Natick Labs, Mail Stop STRNC/YBF, Natick, MA 01760



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Nutritional Needs in Hot Environments: Applications for Military Personnel in Field Operations 11 Situational Influences on Food Intake Edward S. Hirsch1 and F. Matthew Kramer INTRODUCTION If one were asked to describe a situation where eating was not likely to occur, the description would probably contain many elements of the battlefield. It is striking that the thorough nutritional surveys taken during World War II were virtually unanimous in reporting the absence of nutritional disease among troops when food supplies were adequate (Bean, 1946; Johnson and Kark, 1946; Youmans, 1955). These surveys also frequently found weight loss (Youmans, 1955). Consistent with these observations, surveys of troops during World War II found that 54 to 73 percent reported that they were hungry during combat (Webster and Johnson, 1945). More recent observations in the Falkland islands (McCaig and Gooderson, 1986) and a retrospective survey of U.S. Marines who had served in World War II, Korea, and Vietnam (Popper et al., 1989) indicated that during combat, troops reported eating considerably less than usual. The picture that emerges is that under combat conditions troops consume sufficient food to avoid frank nutritional disease but do not consume enough food to meet their energy needs, and some weight loss occurs. THE UNDERCONSUMPTION PROBLEM During the past 10 years, the full range of current military rations has been rigorously tested under various field and climatic conditions by the 1   Edward S. Hirsch, U.S. Army Natick Labs, Mail Stop STRNC/YBF, Natick, MA 01760

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Nutritional Needs in Hot Environments: Applications for Military Personnel in Field Operations U.S. Army Natick Research Development and Engineering Center and the U.S. Army Research Institute of Environmental Medicine. With one instructive exception, these studies have uniformly found that energy intake in the field is not sufficient, and weight loss occurs. Of the various military rations, the meal, ready-to-eat (MRE), a general purpose ration designed to be eaten when hot food is not available, has undergone the most thorough testing in the widest variety of circumstances. Table 11-1 shows the composition of the menus in an early version of this ration, the MRE IV. Newer improved versions are similar in configuration, with each meal consisting of an entree, a dessert, a beverage, crackers and a spread, and a starch in some instances. Hot sauce, fruit-flavored beverages, and new or reformulated items as well as larger entrees have replaced many of the items in Table 11-1. MRE IV provided 3669 calories in three meals whereas MRE VIII provides over 3900 calories in three meals. Table 11-2 shows the results of nine studies conducted with various versions of the MRE fed as the sole source of subsistence for periods ranging from 5 to 34 days, in environments as different as Hawaii and Alaska, and with troops that were relatively inexperienced compared to the highly trained and disciplined U.S. Army Special Forces. Caloric intake and body weight loss varied with the nature of the environment, duration of the test, experience of the participating troops, and version of the MRE tested. However, because of nonsystematic variations across tests, it is impossible to attribute differences in intake and weight loss to these factors independently. What is clear from this table is that energy intake is not sufficient and that weight loss occurs when this ration is fed as the sole source of food. The trend is likely to be even more pronounced in the high heat environment of the desert where the MRE has yet to be tested. PROBLEM DEFINITION The question arises whether these observations are an immutable fact of military feeding in the field, which those responsible for the health and well-being of troops will have to acknowledge and plan for, or whether their source can be uncovered and the situation can be remedied. What factors are responsible for the underconsumption of operational rations? WHY IS RATION INTAKE INSUFFICIENT? Most troops and their leaders would probably explain the inadequate consumption of rations in terms of the nature and quality of the food. However, this is probably not the complete answer for several reasons. First, the various field tests of the MRE have generally shown that troops report the MRE to be acceptable on a 9-point hedonic scale. For example, in a 34-day

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Nutritional Needs in Hot Environments: Applications for Military Personnel in Field Operations TABLE 11-1 Menus in the Meal, Ready-To-Eat (MRE) IV Ration Menu No. Entree Other Components 1 Pork sausage patty, freeze-dehydrated; catsup, dehydrated; applesauce; crackers Cheese spread; cookies, chocolate-covered; cocoa beverage powder 2 Ham/chicken loaf; strawberries, freezedehydrated; crackers Peanut butter; pineapple nut cake 3 Beef patty, freeze-dehydrated; soup and gravy base; beans with tomato sauce; crackers Cheese spread; brownies, chocolate-covered; candy 4 Beef slices with barbecue sauce; crackers; peanut butter; cookie, chocolate-covered Peaches, freeze-dehydrated; candy 5 Beef stew; crackers; peanut butter; fruit, mixed, freeze-dehydrated Cherry nut cake; cocoa beverage powder 6 Frankfurters; catsup, dehydrated; beans with tomato sauce; crackers Jelly; candy; cocoa beverage powder 7 Turkey, diced with gravy; potato patty, freeze-dehydrated; beans with tomato sauce; crackers Maple nut cake; candy 8 Beef, diced with gravy; beans with tomato sauce; crackers Cheese spread; brownie, chocolate-covered 9 Cooked beef or chicken à la king; catsup, dehydrated; crackers; cheese spread Fruitcake; cocoa beverage powder 10 Meatballs with barbecue sauce; potato patty, freeze-dehydrated; crackers Jelly; chocolate nut cake; cocoa beverage powder 11 Ham slices; crackers; cheese spread; peaches, freeze-dehydrated Orange nut roll; cocoa beverage powder 12 Chicken loaf or ground beef with spiced sauce; crackers; peanut butter; strawberries, freeze-dehydrated Cookies, chocolate-covered; candy NOTE: All menus include instant coffee; dry, nondairy cream substitute; granulated sugar; salt; and candy-coated chewing gum. Nonfood components are spoon, matches, and toilet paper. test, the average acceptability rating of all items in the ration was 7.05, which corresponds to the description like moderately on the acceptability scale, and there was no indication that food acceptability decreased over time despite an almost 30 percent reduction in food intake from the first week of the test to the last (Fox et al., 1989; Hirsch et al., 1985). These observations clearly suggest that the nature of the food is not the sole or perhaps not even a critical factor in limiting consumption of the MRE in field tests.

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Nutritional Needs in Hot Environments: Applications for Military Personnel in Field Operations TABLE 11-2 Caloric Intake and Body Weight Loss in Troops Fed Only MRE (Meal, Ready-to-Eat) Meals Ration Environment Eating Conditions Caloric Intake (Kcal) Body Weight Loss (%) Reference MRE IV Temperate, 6000 feet, Hawaii Three MREs per day for 34 days. Issued three per day, no special provisions for heating, training exercise. 2189 5.8 Hirsch et al., 1985 MRE IV Temperate, 7200 feet, Hawaii Three MREs per day for 12 days, ran strenuous cross-country course for 2 hours per day for 7 days. 2282 3.0 Askew et al., 1986 MRE IV MRE VII Improved MRE Temperate, 6000 feet, 35° to 80°F, Hawaii Three MREs per day for 11 days, no provisions for heating food. 2517 2517 2842 2.98 3.20 2.28 Popper et al., 1987 MRE VI Temperate, cool, 40° to 51°F, Vermont Thirty days, Special Forces, surveillance, reconnaissance, no foraging permitted. 2782; no trends over time 2.2 Askew et al., 1987 MRE V Cold, 4° to 35°F, White Mt. National Forest Four MREs per day for 10 days, outside all the time. 2733 4 Engell et al., 1987 Improved MRE VIII Cold, Mountain Warfare Training Center Four MREs per day; days 1-5 in field, 6-7 in garrison, 8-11 in field; leadership course; high activity. 3217 3.3 Morgan et al., 1988 MRE VIII Cold, 14° to 43°F, Wisconsin Four MREs per day for 3 days, three different heating methods,* ate outside. 2250 (canteen cup stand) 2289 (ration heater pad) 2206 (control) 1.7 2.1 2.5 Lester et al., 1990

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Nutritional Needs in Hot Environments: Applications for Military Personnel in Field Operations Ration Environment Eating Conditions Caloric Intake (Kcal) Body Weight Loss (%) Reference Four MRE VI Cold,-40° to +35°F, Alaska Ten days, some days high activity other days defensive position, meals eaten in tents. 2009 2802 2830 2.8 2.0 1.9 Edwards et al., 1989 Four MRE VIII Three MRE VI and supplement           Three MRE VIII and supplement     3553 1.7   Three MRE VIII and supplement Cold,-55° to +26°F, Alaska Air assault and defensive positions, meals eaten in warm tents. 2729 1.6 Edwards et al., 1990 * Three groups of U.S. Marines were provided with different heating methods. One group was given a canteen cup stand and a more-than-sufficient supply of heat tabs. A second group was given ration heater pads and the third group, the control, was given the Optimus Hiker Stove, which is standard issue by the Marine Corps.

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Nutritional Needs in Hot Environments: Applications for Military Personnel in Field Operations A much stronger argument against the notion that low intakes of rations in the field are due to the nature of the food derives from a series of studies conducted where the identical ration was fed either in the field or in a dining room environment. LABORATORY AND FIELD DIFFERENCES The impetus for the initial laboratory study of the MRE arose because this ration had never been tested as the sole source of food for extended periods of time. Military planners and logisticians would like to be able to provide only packaged operational rations to troops for prolonged time periods. This type of subsistence plan would obviously save on equipment, personnel, and money if it could be accomplished without compromising troop morale and performance. In addition, information was needed to set policy on how long the MRE could be fed as the sole source of food without affecting health and nutritional status. It seemed prudent to determine if intake was adequate under controlled conditions prior to field testing, where serious nutritional and health problems might develop, at which time they would be more difficult to treat. In response to these concerns, a laboratory study was conducted with paid student volunteers at the Massachusetts Institute of Technology (E. Hirsch and F. M. Kramer, unpublished data). One group of 17 healthy, normal-weight male students was fed the MRE IV as their sole source of food for 6 weeks. A second group of 16 subjects was fed freshly prepared food that provided 3600 calories per day and closely matched the MRE in macronutrient composition. The control diet was fed in a 12-day menu cycle and consisted of high-preference food items offered in traditional meals. Both groups ate in a small, pleasant dining room with meals available at traditional times for a 2-hour period. Subjects eating the MRE were free to exchange items with each other as is typical of the field. Uneaten MRE components were noted and were available for later consumption by members of the MRE group. The control group could also consume extra food if, at the end of a meal, there were leftovers in the kitchen. Thus, it was possible for some subjects to consume more than the 3600 calories provided in a day's allotment. The MRE was provided at ambient temperature, but components could be heated in a nearby microwave oven. Similarly, hot and cold water was available for mixing beverages or rehydrating ration components. Dinner plates, silverware, bowls, glasses, and cups were available to the MRE group for consuming their food and beverages. The general eating environment can best be described as pleasant, clean, and social. Figure 11-1 shows that during the first two weeks of the experiment the two dietary groups had comparable levels of energy intake. During later weeks, although intake remained relatively constant in the control group it

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Nutritional Needs in Hot Environments: Applications for Military Personnel in Field Operations FIGURE 11-1 Mean daily caloric intake for student volunteers fed three MREs per day or freshly prepared food (control) for 6 weeks. SOURCE: Kramer et al. (1992); used with permission. declined in the MRE group to a value of 3017 calories per day in the final week of the study. Mean caloric intake averaged 3465 calories per day in the control group and 3149 in the MRE group over the course of the experiment. The group differences in caloric intake and the decline in intake over time by the MRE group were statistically reliable (p's < 0.01). At these levels of food intake the control group showed a slightly positive energy balance and gained 0.68 kg over the six weeks of the study whereas the MRE group showed a slightly negative energy balance and lost 0.69 kg. The group differences in energy intake are not readily accounted for by differences in food acceptability, as measure by hedonic ratings. In this study the ration was as highly rated as the freshly prepared food and the reduction in consumption that developed over time in the ration group was not accompanied by changes in food acceptability ratings. At this juncture an explanation of why caloric intake dropped in the MRE group awaits additional research. These findings contrast sharply with data from the field. When troops were fed MRE IV as their sole source of food for 34 days, their average energy intake was only 2190 calories per day (Hirsch et al., 1985; Wenkam et al., 1989). Thus, in the field, intake of the identical ration was almost 1000 calories lower than it was in a dining room environment. Differences in food intake that were observed in the preceding studies suggest that the nature of the feeding environment can dramatically affect daily energy intake. However, it is also possible that this difference is due

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Nutritional Needs in Hot Environments: Applications for Military Personnel in Field Operations to comparing a student population to infantry troops. These populations differ in many dimensions that could affect intake such as, fitness, experience with military food, perceptions of the military and military rations, ethnic and racial composition and food habits. Accordingly, a second study of this type was conducted where troops were fed an improved version of the ration (MRE VIII) either in a field setting or in a garrison dining room (E. Hirsch and F. M. Kramer, unpublished data) for 5 days. The troops in the field were engaged in small-unit training and were provided with three MRE VIIIs, which provide approximately 3900 calories per day. The garrison group ate all meals for a 5-day period at fixed times in a dining room. Meals were prepared and served, restaurant style, on individual trays with plates, bowls, cups, and utensils. Serving sizes were identical to those provided in the ration packages with the exception that cold beverages were served in 200-ml rather than 355-ml portions. Additional portions were available, and subjects could also request ration items for between-meal snacks. Thus, garrison subjects were able to consume more than 3900 calories per day. The field group received one freshly prepared meal on the first and fifth day of the study. For this reason intake on only the middle 3 days, when they were consuming only operational rations, was analyzed. Troops who received rations in the dining room consumed 3848 calories per day compared to the field group, which consumed 2870 calories per day. Level of intake in the field was similar to the level previously observed in a field test with a prototype version of the MRE that was very similar to MRE VIII in a temperate environment (Popper et al., 1987). The large difference in food intake when the MRE VIII was fed to troops in the field compared to troops in a garrison dining hall replicates our earlier finding of about a 1000 calorie difference in intake when the MRE IV was fed to students in a dining room relative to troops in the field. The same finding with more similar subjects in the two eating environments (field versus garrison) strengthens the view that situational factors, such as the nature of the feeding environment, play a critical role in controlling human food intake. To identify specific aspects of the feeding environment that promote this higher food intake in the dining room setting, levels of intake of various classes of food in the ration were examined. Figure 11-2 shows that consumption of desserts and cold beverages was almost 100 percent higher in the dining room than the field, while intake of the other ration components was similar. Higher intake of these items was due to dining room consumption rather than to between-meal snacks. Why these two ration components were consumed at such markedly higher levels remains an open question. A final example of field-dining room differences in energy intake pro-

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Nutritional Needs in Hot Environments: Applications for Military Personnel in Field Operations FIGURE 11-2 Mean daily caloric intake from each food class of the MRE (meal, ready-to-eat) for troops in garrison or in the field. vides additional support for the notion that the nature of the feeding situation has a substantial influence on food intake. Over the past several years, the U.S. Army Research Institute of Environmental Medicine has been assessing the impact of the Army's initiatives to improve the healthfulness of the diet eaten by troops in garrison dining facilities. As part of this effort researchers have examined the nutrient intakes of troops in garrison over 7-day periods. Table 11-3 shows the level of caloric intake they have observed in five studies of this type where troops were provided with three A-ration meals per day. In contrast to operational rations, such as the MRE, which are designed to be eaten hot or cold from shelf-stable, packaged components, A-ration meals consist of fresh foods, prepared and cooked in the field. A remarkably narrow range of caloric intakes (2978 to 3199) was measured in troops that ranged from new recruits in basic training (Fort Jackson) to those attending a leadership course (Fort Riley) and in facilities that were operated by either the military or contractors as illustrated in the first five studies in the table. The final entry in this table is from a field study where, due to unusual circumstances, an artillery unit was engaged in sustained operations for an 8-day period; where sleep was limited and fragmented; and where three A-ration meals per day were provided. The hot meals were brought to the troops in the field, ample time for eating was allowed, and seconds were available. Under these conditions, troops in the field consumed an average of 3713 calories per day and gained 0.8 kg over

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Nutritional Needs in Hot Environments: Applications for Military Personnel in Field Operations TABLE 11-3 Energy Intake by Troops Fed A-Rations in the Garrison or Field for Three Meals per Day Population Location Energy Intake in Calories (Standard Deviation) Reference 43 Male students attending primary leadership development course; attended all meals Fort Riley 3112 (758) Carlson et al., 1987 31 Male soldiers stationed at Ft. Lewis; most meals in dining facility Fort Lewis 3173 (616) Szeto et al., 1987 54 Male soldiers stationed at Ft. Devens who habitually ate at dining hall Fort Devens I 2978 (527) Szeto et al., 1988 52 Male soldiers stationed at Ft. Devens who habitually ate at dining hall Fort Devens II 3165 (511) Szeto et al., 1989 41 Male and 40 female basic trainees; limited meal time; socializing discouraged Fort Jackson 3199 (736), men 2467 (560). women Rose et al., 1989 31 Male artillery soldiers engaged in 8 days of sustained operations; food brought to them, and ample time allowed to eat Fort Sill 3713 (785) gained 0.8 kg in 8 days Rose and Carlson, 1987 the 8 days. The male soldiers in the field study consumed an average of 588 calories per day more than the men in the combined garrison studies. Perhaps the higher A-ration intake in the field occurred because in these unusual circumstances feeding was in some sense easier and more convenient than even in the garrison dining facility. The observed weight gain in a field setting with A-rations is also in marked contrast to the typical weight loss of 1–2 kg in an MRE field trial of comparable duration. SITUATIONAL INFLUENCES The question arises why such large differences in food intake are observed when the identical ration is provided in garrison dining facilities or in a field setting. This laboratory has begun to study how aspects of the eating situation other than food affect food acceptability and consumption

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Nutritional Needs in Hot Environments: Applications for Military Personnel in Field Operations both in single meals and over longer periods of time. The dimensions of the eating situation being studied fall into the general areas of constraints on food intake, social influences, and time of day. Constraints on Food Intake For most organisms, food and water rarely are freely available. Time and effort must be expended to obtain these commodities. Animal research has demonstrated clear relationships between patterns of ingestion and food choice and the cost-benefit structure of an animal's niche and current habitat (for example, Collier, 1989). Although the conceptual leap from animal models of optimal foraging to human feeding behavior is substantial, these authors believe that a comprehensive model of human ingestive behavior must ultimately embrace this class of variables. Further, a consideration of these variables probably will provide insight into the factors that influence the initiation, continuation, and termination of feeding by troops in the field and in combat. Reflecting on the events involved in preparing, consuming, and cleaning up from a meal of operational rations in the field indicates that a series of time-consuming and effortful actions may be required. Potential actions to be carried out include finding a safe or protected location, finding water, rendering it potable, cleaning oneself, opening ration packages, rehydrating foods and beverages that require it, choosing a heating method, actually heating those items one wants hot, and finally eating food items contained in as many as five different packages. If the entire meal is to be eaten in one setting, a place to eat that is relatively flat and dry must be found or prepared. Throughout this entire sequence, orders to move on or perform another task may be issued. Cleaning up may involve burying or burning trash and cleaning a canteen cup if it was used to heat food or prepare beverages. These events become more difficult in a cold, dark, or muddy environment. These constraints on feeding appear to play a major role in limiting the intake of operational rations under field conditions. A corollary of this conjecture is that whatever makes eating easier, less time consuming, and free from situational limitations will lead to higher levels of food intake. The scene just described is obviously complex, with many factors that are difficult to operationalize or to quantify. Studies that vary the effort or cost, of obtaining food may provide an appropriate model for a better understanding of eating behavior in this environment. The literature is limited on the effects of either cost or effort, broadly defined to include physical cost, monetary cost, physiological cost, or cost in a cost-benefit sense on human ingestion. Most of the initial studies were conducted in the context of testing Schachter's (1971) hypothesis that the obese differ from normal-weight individuals in that their feeding behavior

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Nutritional Needs in Hot Environments: Applications for Military Personnel in Field Operations FIGURE 11-7 Mean change in acceptability on a 100-mm visual analogue scale of food consumed in a lunch meal following negative or positive comments at the start of the meal. foods are considered appropriate for only selected meals. In particular, a distinction exists between morning meals and meals later in the day. Although many breakfast foods are eaten later in the day, few people would consider roast beef, vegetables, or ice cream as appropriate for breakfast. Operational military rations have been especially noted for lacking sufficient numbers of acceptable breakfast meals. Soldiers comment that they would like to have more breakfast meals and better ones than those presently available. Furthermore, when MREs are the sole source of food, soldiers eat less and rate the food as less acceptable at morning meals (Hirsch et al., 1985; Lester et al., 1990). One study found effects of time of day on hedonic ratings (Birch et al., 1984), but recent reports also show that even under normal day-to-day conditions, breakfast is typically the smallest meal of the day (Chao and Vanderkooy, 1989; Fricker et al., 1990). Thus, whether time of day is affecting overall intake requires further exploration. To better determine the relevance of time of day, this laboratory conducted a study in which subjects ate four meals (Kramer et al., 1991). Two meals were served at 8:00 a.m. and two at 12:00 noon. One meal at each time consisted of lunch-type foods such as a turkey sandwich, and one consisted of breakfast foods such as bacon and eggs. Subjects were given a serving of each item with additional servings available on request. Contrary

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Nutritional Needs in Hot Environments: Applications for Military Personnel in Field Operations to what was expected, no clear effect of meal "appropriateness" was found. Mean caloric intake at each meal is shown in Figure 11-8. Both the time when the meal was eaten and the type of food served affected consumption. Subjects ate more at noon than at 8:00 a.m., and subjects ate more when offered a lunch menu than a breakfast menu. The hypothesized statistical interaction between menu type and serving time did not approach significance. Hedonic ratings were also not affected by time of day. These results suggest that the best strategy to improve consumption is to focus primarily on developing the most acceptable and nutritious meals possible without regard to their time of day appropriateness. Interestingly, subjects' hunger ratings after the meal gave some indication that appropriateness is a salient feature. Although changes in hunger from immediately before to after the meal did not differ across the meal, hunger did recover more rapidly following inappropriate meals than following appropriate meals. Given that intake and acceptance were not affected by time of day, the importance of this finding remains to be determined. FIGURE 11-8 Mean caloric intake in meals as a function of time of day and type of food.

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Nutritional Needs in Hot Environments: Applications for Military Personnel in Field Operations The results suggest that when subjects do not have a choice about type of food, the appropriateness of those foods for that time of day will have little impact on intake or hedonic ratings. However, as noted earlier, soldiers engaged in field training typically eat less and rate the foods lower for morning meals than for meals at other times of day. Whether this finding merely reflects that morning meals tend to be smaller or is more closely linked to a lack of appropriate breakfast foods cannot be determined with current data. CONCLUSIONS AND RECOMMENDATIONS Three major themes are developed in this review. First, a consistent pattern of underconsumption relative to maintenance needs is apparent when troops subsist on operational rations in combat or training environments. Second, the dining room-laboratory environment embodied features that support substantially higher levels of food intake than a field environment. Third, seemingly minor changes in the feeding situation can have marked effects on food acceptance, food choice, and food intake. It is possible to translate these themes into recommendations that are relevant to troops living and working in hot weather environments, with the caveat that there is limited information concerning the specific effects of situational factors on human food intake to strongly support particular conclusions. The general conceptual model posited here says that whatever makes eating in the field easier and less constrained will enhance consumption. This approach could be accomplished through military doctrine, command emphasis, ration design and configuration, or materials used in food preparation and disposal. Similarly, social factors could be exploited in a direct fashion, such as by encouraging scheduled group feeding or through leadership influence and example. These authors believe the latter in tandem with marketing and training offers particular promise. Although instituting a policy of eating with one's buddies at every meal is not possible, officers can be given a basis for describing, and encouraged to describe, rations in a positive way. REFERENCES Asch, S. 1956 Studies of independence and conformity: A minority of one against a unanimous majority. Psychol. Monogr. 70:No. 9, Whole No. 416. Askew, E.W., J.R. Claybaugh, S.A. Cucinell, A.J. Young, and E.G. Szeto 1986 Nutrient intakes and work performance of soldiers during seven days of exercise at 7,200 ft altitude consuming the meal, ready-to-eat ration. Technical Report T3-87. U.S. Army Research Institute of Environmental Medicine, Natick, Mass.

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Nutritional Needs in Hot Environments: Applications for Military Personnel in Field Operations Askew, E.W., I. Munro, M.A. Sharp, S. Siegel, R. Popper, M.S. Rose, R.W. Hoyt, J.W. Martin, K. Reynolds, H.R. Lieberman, D.B. Engell, and C.P. Shaw. 1987 Nutritional status and physical and mental performance of special operations soldiers consuming the ration, lightweight or the meal, ready-to-eat military field ration during a 30-day field training exercise. Technical Report T7-87. U.S. Army Research Institute of Environmental Medicine, Natick, Mass. Axelson, M.L. 1986 The impact of culture on food related behavior. Ann. Review Nutr. 6:345–363. Bean, W.B. 1946 Nutrition survey of American troops in the Pacific. Nutr. Rev. 4:257–259. Birch, L.L., J. Billman, and S.S. Richards 1984 Time of day influences food acceptability. Appetite 5:109–116. Carlson, D., T. Dugan, J. Buchbinder, J. Allegretto and D. Schnakenberg 1987 Nutritional assessment of the Ft. Riley Non-Commissioned Officer Academy Dining Facility. Technical Report 14-87. U.S. Army Institute of Environmental Medicine, Natick, Mass. Chao, E.S.M, and P.S. Vanderkooy 1989 An overview of breakfast nutrition. J. Can. Diet. Assoc. 50:225–228. Collier, G. 1989 The economics of hunger, thirst, satiety and regulation. Ann. N.Y. Acad. Sci. 575:136–154. de Castro, J.M. 1988 Physiological, environmental, and subjective determinants of food intake in humans: A meal pattern analysis. Physiol. Behav. 44:651–659. 1990 Social facilitation of duration and size but not rate of the spontaneous meal intake of humans. Physiol. Behav. 47:1129–1135. de Castro, J.M., and E.S. de Castro 1989 Spontaneous meal patterns of humans: Influence of the presence of other people. Am. J. of Clin. Nutr. 50:237–247. de Castro, J.M., E.M. Brewer, D.K. Elmore, and S. Orozco 1990 Social facilitation of the spontaneous meal size of humans occurs regardless of time, place, alcohol or snacks. Appetite 15:89–101. Durrant, M.L., and J.S. Garrow 1982 The effect of increasing the relative cost of palatable food with respect to ordinary food on total-energy intake of eight obese inpatients. Int. J. Obes. 6:153–164. Edelman, B., D. Engell, P. Bronstein, and E. Hirsch 1986 Environmental effects on the intake of overweight and normal-weight men. Appetite 7:71–83. Edwards, J.S.A., D.E. Roberts, T.E. Morgan, and L.S. Lester 1989 An evaluation of the nutritional intake and acceptability of the meal, ready-to-eat consumed with and without a supplemental pack in a cold environment. Technical Report T18-89. U.S. Army Research Institute of Environmental Medicine, Natick, Mass. Edwards, J.S.A., D.E. Roberts, S.H. Mutter, and R.J. Moore 1990 A comparison of the meal, ready-to-eat VIII with supplemental pack and the ration cold weather consumed in an arctic environment. Technical Report T21-90. U.S. Army Research Institute of Environmental Medicine, Natick, Mass. Engell, D., and E. Hirsch 1991 Environmental and sensory modulation of fluid intake in humans. Pp. 382–390 in Thirst: Physiological and Psychological Aspects, D.J. Ramsey and D. Booth, eds. London, U.K.: Springer-Verlag.

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Nutritional Needs in Hot Environments: Applications for Military Personnel in Field Operations Engell, D.B., D.E. Roberts, E.W. Askew, M.S. Rose, J. Buchbinder, and M.A. Sharpe 1987 Evaluation of the ration cold weather during a 10-day cold weather field training exercise. Natick Technical Report TR-87/030. U.S. Army Natick Research, Devel opment and Engineering Center, Natick, Mass. Engell, D., F.M. Kramer, S. Luther, and S.O. Adams 1990 The effect of social influences on food intake. Presented at the Society for Nutrition Education 1990 Annual Meeting, Anaheim, Calif. Fox, M., N. Wenham, and E. Hirsch 1989 Acceptability studies of military ration: Meal, ready-to-eat. J. Foodserv. Systems 5:189–197. Fricker, J., S. Giroux, F. Fumeron, and M. Apfelbaum 1990 Circadian rhythms of energy intake and corpulence status in adults. Int. J. Obes. 14:387–393. Galef, B.G. 1986 Social interaction modifies learned aversions, salt appetite, and both palatability and handling-induced dietary preference in rats (Rattus norvegicus). J. Comp. Psychol. 100:432–439. Haney, C., W.C. Banks, and P. Zimbardo 1973 Interpersonal dynamics in a simulated prison. Int. J. Criminol. Penol. 1:69–97. Hirsch, E., H.L. Meiselman, R.D. Popper, G. Smits, B. Jezior, I. Lichton, N. Wenkam, J. Burt, M. Fox, S. McNutt, M.N. Thiele, and O. Dirige 1985 The effects of prolonged feeding meal, ready-to-eat (MRE) operational rations. Technical Report Natick TR-85/035. U.S. Army Natick Research, Development and Engineering Center, Natick, Mass. Johnson, R.E., and R.M. Kark 1946 Feeding problems in man as related to environment. An analysis of United States and Canadian army ration trials and surveys, 1941–1946, Chicago, Quartermaster Food and Container Institute for the Armed Forces, Research and Development Branch, Office of the Quartermaster General. Klesges, R.C., D. Bartsch, J.D. Norwood, D. Kautzman, and S. Haugrud 1984 The effects of selected social and environmental variables on the eating behavior of adults in the natural environment. Int. J. Eating Disord. 3:35–41. Kramer, F.M., K. Rock, and D. Engell 1992 Effects of time of day and appropriateness on food intake and hedonic ratings of morning and midday. Appetite 14:1.13. Lappalainen, R., and L.W. Epstein 1990 A behavioral economics analysis of food choice in humans. Appetite 14:81–93. Lester, L.S., and F.M. Kramer 1991 The effects of heating on food acceptability and consumption. J. Foodserv. Systems. Lester L.S., F.M. Kramer, J. Edinberg, S. Mutter, and D.B. Engell 1990 Evaluation of the canteen cup stand and ration heater pad: Effects on acceptability and consumption of the meal, ready-to-eat in a cold weather environment. Technical Report Natick TR-90/008L. U.S. Army Natick Research, Development and Engineering Center, Natick, Mass. Levitz, L. 1975 The susceptibility of feeding to external control. Pp. 53–60 in Obesity in Perspective, G. A. Bray, ed. Department of Health, Education, and Welfare Publication No. NIH 75-708. Washington, D.C.: U.S. Government Printing Office. Lichton, I.J., J.B. Miyamura, and S.W. McNutt 1988 Nutritional evaluation of soldiers subsisting on meal, ready-to-eat operational ra-

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Nutritional Needs in Hot Environments: Applications for Military Personnel in Field Operations tions for an extended period: Body measurements, hydration, and blood nutrients. Am. J. Clin. Nutr. 48:30–37. McCaig, R.H., and C.Y. Gooderson 1986 Ergonomic and physiological aspects of military operations in a cold wet climate. Ergonomics 29:849–857. Messer, E. 1984 Anthropological perspectives on diet. Annu. Rev. Anthropol. 13:205–249. Meyers, A.W., A.J. Stunkard, and M. Coll 1980 Food accessibility and food choice. Arch. Gen. Psychiatry 37:1133–1135. Milgram, S. 1973 Obedience to Authority. New York: Harper and Row. Morgan, T.E., L.A. Hodgess, D. Schilling, R.W. Hoyt, E.J. Iwanyk, G. McAninch, T.C. Wells, and E.W. Askew 1988 A comparison of the meal, ready-to-eat, ration, cold weather and ration, light weight nutrient intakes during moderate altitude cold weather field training operations. Technical Report T5-89. U.S. Army Research Institute of Environmental Medicine, Natick, Mass. Polivy, J., and C.P. Herman 1985 Dieting and binging: A causal analysis. Am. Psychol. 40:193–201. Polivy, J., C.P. Herman, J.C. Younger, and B. Erskine 1979 Effects of a model on eating behavior: The induction of a restrained eating style. J. Pers. 47:100–117. Popper, R., E. Hirsch, L. Lesher, D. Engell, B. Jezior, B. Bell, and W.T. Matthew 1987 Field evaluation of Improved MRE, MRE VII, and MRE IV. Technical Report Natick TR-87/027. U.S. Army Natick Research, Development and Engineering Center, Natick, Mass. Popper, R., G. Smits, H.L. Meiselman, and E. Hirsch 1989 Eating in combat: A survey of U.S. Marines. Milit. Med. 154:619–623. Rose, M.S., and D.E. Carlson 1987 Effect of A-ration meals on body weight during sustained field operations. Technical Report T2-87. U.S. Army Research Institute of Environmental Medicine, Natick, Mass. Rose, R.W., C. Baker, C. Salter, W. Wisnaskas, J.S.A. Edwards, and M.S. Rose 1989 Dietary assessment of U.S. Army basic trainees at Fort Jackson, SC. Technical Report T6-89. U.S. Army Research Institute of Environmental Medicine , Natick, Mass. Rozin, P., and T.A. Vollmecke 1986 Food likes and dislikes. Ann. Rev. Nutr. 6:433–456. Salter, C.A., D. Engell, F.M. Kramer, L.S. Lester, J.J. Kalick, L.L. Lester, S.L. Dewey, and D. Caretti 1991 The relative acceptability and consumption of the current and proposed versions of the T Ration. Technical Report 91/031. U.S. Army Natick Research, Development and Engineering Center, Natick, Mass. Schachter, S. 1971 Some extraordinary facts about obese humans and rats. Am. Psychol. 26:129–144. Schachter, S., and L.N. Friedman 1974 The effects of work and cue prominence on eating behavior. Pp. 11–14 in Obese Humans and Rats, S. Schachter and J. Rodin, eds. Potomac, Md.: Earlbaum Associates. Schachter, S., and L. Gross 1968 Manipulated time and eating behavior. J. Personal. Soc. Psychol. 10:98–106.

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Nutritional Needs in Hot Environments: Applications for Military Personnel in Field Operations Singh, D., and S. Sikes 1974 Role of past experience on food-motivated behavior of obese humans. J. Comp. Physiol. Psychol. 86:503–508. Smith, E.E. 1961 The power of dissonance techniques to change attitudes. Public Opin. Q. 25:626–639. Striegel-Moore, R.H., L.R. Silberstein, and J. Rodin 1986 Toward an understanding of risk factors for bulimia. Am. Psychol. 41:246–263. Szeto, E.G., D.E. Carlson, T.B. Dugan, and J.C. Buchbinder 1987 A comparison of nutrient intakes between a Ft. Riley contractor-operated and a Ft. Lewis military-operated garrison dining facility. Technical Report T2-88. U.S. Army Research Institute of Environmental Medicine, Natick, Mass. Szeto, E.G., T.B. Dugan, and J.A. Gallo 1988 Nutrient intakes of habitual diners in a military-operated garrison dining facility—Ft. Devens I. Technical Report T3-89. U.S. Army Research Institute of Environ mental Medicine, Natick, Mass. Szeto, E., J.A. Gallo, and K.W. Samonds 1989 Passive nutrition intervention in military-operated garrison dining facility—Ft. Devens II. Technical Report T7-89. U.S. Army Research Institute of Environmental Medicine, Natick, Mass. Webster, E.C., and F.H. Johnson 1945 Questionnaire of wounded soldiers. Part II. Data on rations in combat and behind the lines. Report No. C6162 to the Associate Committee Army Medical Research, National Research Council Canada. Wenkam, N.S., M. Fox, M.N. Thiele, and I.J. Lichton 1989 Energy and nutrient intakes of soldiers consuming MRE operational rations: Physiological correlates. J. Am. Diet. Assoc. 89:407–409. Youmans, J.B. 1955 Malnutrition and deficiency diseases. Pp. 159–170 in Preventive Medicine in World War II, J.B. Coates, Jr., and E.C. Hoff, eds. Washington, D.C.: Office of the Surgeon General, Department of the Army. DISCUSSION DR. NESHEIM: Any questions? PARTICIPANT: A couple of comments. One of them is about getting up in the morning—the attendance being low for the breakfast items in the field kitchens—when you talk about the notion about how much work is involved, breakfast is a good case. Going to breakfast is a little bit more trouble, often, than it is to go to eat at lunchtime when you are already up. But the other thing that I think needs to be emphasized is that as the Army goes more and more to continuous operations which go around the clock, it is really very difficult to say what time of day is breakfast. So the notion of the meal that is served early in the morning being everybody's breakfast, I think, needs to be reevaluated because for many of the troops, particularly the light infantry, who do most of their raids at

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Nutritional Needs in Hot Environments: Applications for Military Personnel in Field Operations night, the meal that they eat early in the morning is the meal they are eating before they go to bed. So the whole notion of what is breakfast becomes very confused and that needs to be given some consideration. PARTICIPANT: One of the things that we heard yesterday from most speakers and you mentioned also, is the availability of time and eating on the run. I have noticed that that is one of the variables that you didn't have any data on, people who had more access to time. DR. HIRSCH: I think it is critical. Since the first MRE test, we have been trying to line up a field study where troop commanders would allow us to schedule meals and provide ample time for eating. Even during a training exercise, troop commanders don't want to relinquish that kind of control and impose that lack of flexibility on themselves. It is a real problem and I think particularly in the heat, which we were fortunate to escape this time around. PARTICIPANT: One other question related to that, we heard about the number of packets that they have to deal with. Would it make sense to consider greater proportions of calories in something that could be consumed between meals, on-the-go type of things. DR. HIRSCH: I think we will probably move in that direction. On-the-go food items are one of the items that troops were asking for. PARTICIPANT: I just want to address the question about putting lunch and dinner type items in breakfast menus and this is in the early 1980s. We only had really about five entrees but they told us that we will eat anything you give us for breakfast. So we went to that concept of putting what we felt were mildly flavored lunch and dinner items at breakfast. The comments that came back, even though they told us to do this, were abominable. They didn't want to see another beef stew or peppers or lasagna or whatever we put—I don't remember. We had excesses that we had to use up for years in the 1984, 1985 and 1986 time frame. I am not saying that in the 1990s now that people are used to it and we have been to work, that that might not work, but we did try that and that was—we lost so much credibility with the agency that was doing menus at the time that I would be reluctant to do that again, and we were listening to the troops. DR. HIRSCH: Yes, but I think at that point in time you were dealing with such a limited range of entrees that were available, that what you were giving them for breakfast they were also seeing for lunch and dinner. No wonder they were upset with you.

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Nutritional Needs in Hot Environments: Applications for Military Personnel in Field Operations PARTICIPANT: I was just curious about the breakfast items. Were they significantly worse? DR. HIRSCH: I invite you to join us for a tray pack breakfast when you are up in Boston. PARTICIPANT: I can tell you that a breakfast tray pack doesn't look very good. PARTICIPANT: Even in a civilian setting, the breakfast meal is usually the one where people are willing to put forth the least effort. They want a breakfast cereal or something you could pour milk on, something that is fast. I would guess that in a military setting, you have the additional effort of having to get up earlier and you have to go to the effort of heating water and rehydrating something. The whole environment would argue against their eating it. It seems like it is almost a set-up to almost ensure that you are going to have minimal consumption. I would think the effort would have to be directed to greater ease of preparation, something that could be eaten cold perhaps. DR. HIRSCH: Well, they are certainly moving in that direction with the breakfast cereals which are very popular. PARTICIPANT: A comment on that, one of the things that people ask for from home to kind of fill that is things like pop tarts and granola bars which they would often eat for breakfast. PARTICIPANT: I notice that now. Kids eat poptarts now without putting them in the toaster. They eat them cold out of the package. DR. HIRSCH: My own guess is that as the American culture moves more and more toward packaged eat-on-the-run foods, it will be much easier for the soldier to find that part of his military ration and be very comfortable with it. In the past, when we have tried to feed people unconventional foods that they have never seen before or had a strange name or a strange sight, they really resist it. Over the past several years there have been some, senior generals had very strong opinions about the rations and let it be known to their troops and you could just see that attitude in working with the troops. As a matter of fact, in testing one of the new versions of the MRE, we were kind of told that before we went to the field with it, we had to test it with his troops, and until his troops told him it was okay, he was going to fight it.

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Nutritional Needs in Hot Environments: Applications for Military Personnel in Field Operations And fortunately, the product was good enough that with this version of the MRE, his troops endorsed it and he went along. But the senior leadership effect is very dramatic. I can't quantify it but I certainly see it every time I am out with troops. PARTICIPANT: To what extent have cold instant breakfasts consumed as beverages been tried? DR. HIRSCH: I can't think of any. PARTICIPANT: Just an editorial comment on whether the leadership has any impact, but one thing that is real obvious in the field is many of the senior NCOs that were in Vietnam had the C rations, whether they like it or not, in their mind it was better. And routinely you will have 18-, 19-year-old soldiers who wouldn't know one if a palette-full dropped on them, will tell you, C rations were much better than MREs. People they trust say it is, so it must be so. DR. NESHEIM: Thank you very much.

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