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Introduction and Background

Not Eating Enough, 1995

Pp. 3–40. Washington, D.C.

National Academy Press

The Committee on Military Nutrition Research (CMNR) has reviewed many studies over the past 10 years that evaluated the acceptance and intake of military food items as part of its continuing task of assessing the nutritional adequacy of military operational rations (see IOM, 1992a for summary). The current main operational ration, the Meal, Ready-to-Eat (MRE), was developed in 1981 as the primary ration to replace the C Ration, which had been the mainstay of operational rations for many years. The MRE is compact, has a long shelf life, and can be issued directly to the individual soldier. It can be eaten with or without heating, and the 3,600 kcal provided by the total ration was designed to meet the Military Recommended Dietary Allowances (MRDAs) (see AR 40-25, 1985) for all nutrients. The MRE was initially developed for use up to 3 days at the start of military operations until other field feeding systems became available. The simplicity of this system, logistically and in terms of reduced need for food preparation personnel, led to the desire to use this ration for extended periods of time (i.e., 10 to 30 days). Field testing was thus ordered to evaluate the effectiveness of the MRE over extended periods of time. Summaries of these field studies can be found in Chapters 6 through 10 of this volume.

The CMNR reviewed many of these studies when they were initially completed and noticed that underconsumption of the ration appeared to be a



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Not Eating Enough: Overcoming Underconsumption of Military Operational Rations 1 Introduction and Background Not Eating Enough, 1995 Pp. 3–40. Washington, D.C. National Academy Press The Committee on Military Nutrition Research (CMNR) has reviewed many studies over the past 10 years that evaluated the acceptance and intake of military food items as part of its continuing task of assessing the nutritional adequacy of military operational rations (see IOM, 1992a for summary). The current main operational ration, the Meal, Ready-to-Eat (MRE), was developed in 1981 as the primary ration to replace the C Ration, which had been the mainstay of operational rations for many years. The MRE is compact, has a long shelf life, and can be issued directly to the individual soldier. It can be eaten with or without heating, and the 3,600 kcal provided by the total ration was designed to meet the Military Recommended Dietary Allowances (MRDAs) (see AR 40-25, 1985) for all nutrients. The MRE was initially developed for use up to 3 days at the start of military operations until other field feeding systems became available. The simplicity of this system, logistically and in terms of reduced need for food preparation personnel, led to the desire to use this ration for extended periods of time (i.e., 10 to 30 days). Field testing was thus ordered to evaluate the effectiveness of the MRE over extended periods of time. Summaries of these field studies can be found in Chapters 6 through 10 of this volume. The CMNR reviewed many of these studies when they were initially completed and noticed that underconsumption of the ration appeared to be a

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Not Eating Enough: Overcoming Underconsumption of Military Operational Rations consistent problem. Typically, soldiers did not consume sufficient calories to meet energy expenditure and consequently lost body weight. The energy deficit has been in the range of 700 to 1,000 kcal/d and thus raises concern about the influence of such a deficit on physical and cognitive performance, particularly over a period of extended use. Anecdotal reports from Operation Desert Storm, for example, indicated that some units may have used MREs as their sole source of food for 50 to 60 days—far longer than the original intent when the MRE was initially field tested. In contrast, studies with special purpose subsistence rations that supplied limited energy (1,500–2,000 kcal), but were based on similar design of the MRE, reported that the rations were fully consumed, and soldier weight losses were experienced as would be predicted by the limited calories in the rations. Systematic records of personnel weight loss and nutritional status were not maintained during the combat situation of Desert Storm. There were, however, no apparent major nutritional problems associated with this long-term use of MREs. Based on continuing research with the MREs as described later in this chapter and in Chapters 6 through 10 of this report, the Army Surgeon General, with concurrence from the Air Force, Marine Corps, and Navy, has recently issued a revised policy statement that ''…allows the MREs to be consumed as the sole source of subsistence for up to twenty-one days" (U.S. Department of the Army, 1995). There have been successive modifications of the MRE since 1981. These modifications in type of food items, diversity of meals, packaging, and food quality have produced small improvements in total consumption but have not significantly reduced the energy deficit that occurs when MREs are consumed. This problem continues in spite of positive hedonic ratings of the MRE ration items in laboratory and field tests. The suboptimal intake of operational rations thus remains a major issue that needs to be evaluated. This report originated from a concern within the military about the consistency of the deficit in energy intake and whether such a decrement could lead to meaningful reductions in physical and/or cognitive performance of troops during military operations. The report focuses on the various factors that may contribute to the reduced intake of operational rations, the potential effect on soldier performance, and suggested steps that may be taken to overcome the problem. The data covered in this report are limited to controlled field studies of operational rations. The information and conclusions drawn from these data, while reflecting the military performance demands in rigorous field conditions and environmental extremes, do not, however, reflect the extreme physical, social, and psychological stress of combat. THE COMMITTEE'S TASK The CMNR of the Food and Nutrition Board (FNB), Institute of Medicine, National Academy of Sciences, was asked to assist in a collaborative program

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Not Eating Enough: Overcoming Underconsumption of Military Operational Rations between scientists in the Military Nutrition Division, U.S. Army Research Institute of Environmental Medicine (USARIEM), and the U.S. Army Natick Research, Development and Engineering Center (NRDEC) to strategies on how to overcome underconsumption of military operational rations. The CMNR's task was to review the data on ration intake in controlled field settings, to determine whether the consistently reported suboptimal energy intake could be termed underconsumption , to evaluate whether this lowered intake could be detrimental to performance, and to discuss strategies that might be effective for increasing ration consumption. The committee was thus charged with reviewing the existing data on ration intake from studies that had been conducted by the Army and integrating current scientific hypothesis with relevant data on factors that depress or, conversely, enhance food intake. Other than anecdotal information, data were not presented on ration intake from soldiers engaged in combat situations. The committee was also asked to address five questions that dealt with the concept of underconsumption as it related to military applications. These questions are listed in Table 1-1. The basic factors and viewpoints of key scientists from USARIEM and NRDEC related to soldier underconsumption were initially discussed with the chair and several members of the CMNR in a small planning session in March, 1993. At this meeting the CMNR indicated their recognition of the complexity of the issues and decided to convene a workshop that would provide more specific information about the military research coupled with relevant presentations from scientists from academic and industry settings. In particular the committee members indicated the workshop scope should include more specific information about (1) Army field feeding logistics; (2) new developments TABLE 1-1 Questions to be Addressed in This Report 1. Why do soldiers underconsume (not meet energy expenditure needs) in field operations? 2. What factors influence underconsumption in field operations? Identify the relative importance of • rations, • environment, • eating situation, and • the individual. 3. At what level of underconsumption is there a negative impact on physical or cognitive performance? 4. Given the environment of military operations, what steps are suggested to enhance ration consumption? To overcome deficits in food intake? To overcome any degradation in physical or cognitive performance? 5. What further research needs to be done in these areas?

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Not Eating Enough: Overcoming Underconsumption of Military Operational Rations in operational rations; (3) an overview of Army research on food intake patterns and factors affecting food intake; (4) recent Army research results on the impact of lowered energy intake on performance; and (5) expert reviews of physiological, psychological, and social factors that influence eating. The workshop therefore was convened on November 3–4, 1993 to assist the CMNR in responding to the Army and provide background information useful for developing its report. This workshop included presentations from military and nonmilitary scientists with expertise in food engineering, food marketing strategies, food science, nutrition, nutritional biochemistry, physiology, psychology, and social factors. A panel discussion was held at the end of the workshop to summarize the findings and discuss potential strategies to increase ration intake. The four invited panelists contributed their expertise in complex data analysis, food development, ingestive behavior, and nutrition education. The panel discussion, summary statements, and recommendations were important contributions to the committee deliberations and conclusions. The invited speakers discussed their presentations with committee members at the workshop and submitted the contents of their verbal presentations as written reports. The committee met after the workshop to discuss the issues raised and the information provided. The CMNR later reviewed the written reports and drew on its collective expertise and the scientific literature to develop the summary, conclusions, and recommendations that appear here and in Chapter 2. Terms Used in This Report The term underconsumption will be used in Part I of this report to represent food intake that has been documented to provide fewer calories than required by energy expenditure on an individual or group basis. Use of the term underconsumption in this manner thereby assumes a longer-term risk of undernutrition if it persists over an extended period of time. In the military sense, a ration is the nutritionally adequate food allotment for one person for one day; a military operational meal is a unit making up one-third of the daily nutritional requirement of a ration. An operational ration is a collective term for rations used in the field or in combat. For operational rations the choice of a specific ration or meal type for individual or group feeding is determined by the tactical and logistical characteristics of the feeding situation, or Mission, Enemy, Troops, Terrain, and Time (METT-T) dependent (Mason et al., 1982; NLABS, 1983). Throughout Part I the committee uses the term ration collectively to represent the five types of current military operational rations (Meal, Ready-to-Eat [MRE], T, B, and A Rations, and the Unitized Group Ration [UGR]). The ration types are described

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Not Eating Enough: Overcoming Underconsumption of Military Operational Rations briefly here and in detail by Gerald A. Darsch and Philip Brandler in Chapter 7. The Meal, Ready-to-Eat (MRE) is an operational ration currently configured as 12 menus with all 12 menus packaged together in a case. Each meal weighs 11/2 pounds (0.7 kg) and comprises six to eight components. The individual meal is packaged in retort1 pouches, and entrees include chicken stew, pork with rice, and spaghetti, with accompaniments of fruit, cookies, cheese crackers, a beverage, and seasonings. Individual meals are nutritionally balanced in accordance with the Office of the Surgeon General's (OTSG) requirements as stated in U.S. Army Regulation 40-25 (1985). The MRE is a general purpose ration that is intended to be carried and consumed in the field in conflict situations where cooks cannot prepare group meals by virtue of the tactical environment. Since 1983, the MREs have been improved continually based on surveys of troop feedback from the field, including early feedback from Operation Desert Shield/Storm; from focus groups; and from individual interviews with soldiers. The Tray Ration (T Ration) is composed of heat-and-serve prepared foods in half-size steam-table (1.66 cubic ft) metal containers, with all necessary components, including napkins, knives, forks, trays, and so on, contained in modules. Each meal is nutritionally balanced in accordance with Army Regulation 40-25 (1985) and includes an entree, a vegetable, a starch, and a dessert. The T Ration provides a 10-d breakfast and a 10-d lunch-dinner menu for 18 military personnel. The most tactically versatile of the group rations, the T Ration provides hot group meals with limited personnel and minimal equipment. The T Ration has been the subject of a product improvement program at NRDEC, and menus have been restructured on a continuous basis to eliminate less acceptable items and to add new, more highly acceptable items. The B Ration is a cook-prepared group meal that requires a field kitchen. All ingredients used to prepare the B Ration are semi-perishable, and therefore, no refrigeration is required. Most of these semi-perishable ingredients are standard institutional-type ingredients such as flour, sugar, and large (# 10) cans of vegetables and meats. In addition, there are 13 unique items that are either dehydrated or chunked and formed. Preparation of these meals in the field using field kitchens is a demanding task that requires considerable culinary skill. The B Ration provides a 10-d breakfast and dinner menu. The A Ration is a meal prepared by cooks in a field kitchen where refrigeration is available, and chilled and frozen products can be provided. 1   In retort processing, packaged foods are heat treated (at approximately 250¹F) under pressure for sufficient time to inactivate food microorganisms. Examples of foods that require retort processing include low acid foods with sufficient moisture to support the growth of microorganisms (e.g., entrees, vegetables, starches, and desserts).

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Not Eating Enough: Overcoming Underconsumption of Military Operational Rations Like the B Ration, this meal requires considerable cooking skill and demands careful inventory management because of both the perishable nature of some ingredients and the total number and quantity of ingredients necessary to prepare and serve meals. The A Ration provides a 10-d breakfast and dinner menu. The Unitized Group Ration (UGR) integrates into a unified system the A Ration minus the perishables, the B Ration, the T Ration, and additional brand-name items that can be quickly prepared. The UGR contains 15 breakfast menu options (5 each of rations A, B, and T) and 30 lunch-dinner menu options (10 each of rations A, B, and T). Each of the meal options is unitized in six containers and provides all of the ingredients, trays, utensils, napkins, condiments, and so on, necessary to feed 100 military personnel. The six containers make up one layer of a pallet, and four layers constitute a pallet load. This system maximizes the efficiency of group feeding in the field and reduces the number of line items a cook must order for a meal to one-tenth the number formerly required. The UGR has been developed recently and is currently under final review. Definition of the Problem and Report Organization To develop answers to the questions posed by the Army, the CMNR sought to identify the magnitude of the lowered consumption experienced by troops in field settings, whether and when the energy deficit affected performance of militarily relevant tasks, and the specific factors involved. In this chapter, initially the committee reviewed the research evidence related to underconsumption and performance. In addressing the data with the assistance of personnel from USARIEM and NRDEC, the committee determined that the situational factors of the eating environment and attributes of the food were the major elements involved in reduced consumption. A review of research findings in these general areas is then presented in the sections that follow with an overview of newly proposed plans for changes of military operational rations and field feeding programs. The CMNR concludes its research synopsis with a discussion of the potential impact of these proposed changes on the underconsumption problem and incorporates a discussion of alternative research and operational strategies suggested at the workshop. LOWERED INTAKE AND PERFORMANCE Overview of Energy Intakes During Military Exercise Problems of suboptimal consumption during military exercise in real-life situations have been studied by the Military Nutrition Division at USARIEM

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Not Eating Enough: Overcoming Underconsumption of Military Operational Rations (see Baker-Fulco, Chapter 8 in this volume). Either food records or, for group feeding situations, visual estimation techniques are used to estimate soldier intakes for from 5 to 30 days. Preweighed or prepackaged rations are used for much of the food in the field. Studies have been done of military groups in garrison dining facilities in normal and training environments to obtain comparative data on energy intake. See Table 1-2 for a summary. Typical energy intakes of military men in garrison situations range from 2,730 to 3,260 kcal/d. When soldiers are actively involved in training, garrison intakes range from 3,200 to 4,650 kcal/d. In field training operations male soldiers had significantly lower intakes, ranging from 2,265 kcal in a study in Bolivia where the MRE and B Rations were fed to individuals in a high-altitude environment (Edwards et al., 1991), to a high of 3,713 kcal at Fort Sill where A Rations were provided three times a day in the field as hot meals at regularly scheduled times (Rose and Carlson, 1986). The Fort Sill study was considered to represent the optimal situation for feeding soldiers in field operations. In another study at Fort Chaffee, a control group received hot meals in a fixed dining facility while the MRE group received the rations in their barracks at scheduled meal times in a thermally neutral environment (C. D. Thomas et al., U.S. Army Research Institute of Environmental Medicine, Natick, Mass., unpublished data). There was weight loss in both groups, but the MRE group lost twice as much weight over 30 days (4.8 percent of body weight versus 2.4 percent in the control group), with a difference in energy intake of about 400 kcal/d. These estimates of deficits have been confirmed in studies of energy expenditure in the field using the doubly labeled water technique, which show a typical daily deficit of 500 to 2,000 kcal (see Chapters 8 and 14). In a recent study of women in a hot environment at Fort Hood, Texas, that provided two B Rations and one MRE per day, the average intake was 2,343 kcal/d, which is close to the MRDA of 2,400 kcal (Rose, 1989). The women in this study maintained their body weight; however, they had liberal access to commercial snack foods. In previous studies in garrison during training, women had similar intakes ranging from 2,314 to 2,592 kcal/d, as compared to nontraining garrison intakes of 1,832 kcal/d (see Baker-Fulco, Chapter 8 in this volume for summary). In the Bolivia study mentioned above (Edwards et al., 1991), the women demonstrated a marked decrease in intake similar to that seen in men at high altitudes with an average intake of only 1,668 kcal/d. In studies conducted in cold weather, energy intakes are found to be much higher, demonstrating the effect of the increased energy requirement in cold-weather exercises. However, the increased level of intake does not offset the increased level of expenditure, as verified by studies conducted in the cold in which doubly labeled water was used to estimate actual energy expenditure (see Baker-Fulco, Chapter 8 in this volume). Many contributing factors such as the ration itself, meal schedules, environment, military and unit command emphasis, military feeding policy,

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Not Eating Enough: Overcoming Underconsumption of Military Operational Rations and individual biological rhythms may be important contributors to underconsumption. Food waste in the field is considerable, with 1,000 to 3,000 kcal/d differences occurring when actual intake of rations is monitored (only 51–78 percent of the ration being eaten). Soldiers, if given the opportunity, throw out foods they do not like (cf., Rose, 1989; Baker-Fulco, Chapter 8 in this volume). Also, there are time constraints that may prevent heating and preparing the rations. There appears to be a fatalistic attitude on the part of commanders and troops about the weight loss, which additionally may contribute to underconsumption and often deliberate dieting (see Baker-Fulco, Chapter 8 in this volume). In summary, energy intake of men and women decreases in the field compared to the garrison during training. In the MRE field studies using doubly labeled water, there appears to be an energy deficit of 500 to 2,000 kcal/d and resultant weight loss for the study participants. When men and women trainees were given the opportunity to augment their rations with snack food or when regularly scheduled hot meals were provided, body weight was maintained. Effects of Ration Modifications in Energy Intake, Weight Change, and Food Acceptance Five studies that compared the original MRE with improved versions containing 15 to 51 percent substitutions of new food items (see Hirsch, Chapter 9 in this volume) increased the ratings of soldier acceptability. However, increases in acceptability were only accompanied by increases in energy intake in four of the five studies. In other studies with improved T Rations, although there was an increase in acceptance, there was no increase in energy intake. These results must be viewed with caution as the limited increase in consumption might be due to the introduction of dietary variety (Rolls and Hetherington, 1989) or to the novelty effect of these new, highly palatable foods. These data thus raise an additional research question of whether heightened acceptance ratings and increased consumption might decline with repeated exposure to these new food items. Edward Hirsch (see Chapter 9 in this volume) has suggested that monotony is likely to set in; however, studies have not been conducted to address this issue. In addition, food acceptance as measured by hedonic ratings represents only one aspect of a complex issue. Certain foods such as bread, high starch-containing vegetables, and milk, which typically receive only average hedonic ratings, will continue to be consumed in quantity when other more highly rated foods will be rejected as no longer palatable (see further discussion later in this chapter and in Chapters 11 and 13). A broader range of foods and menus with increased variety may need to be considered. There are 18 MREs now proposed, but the effect of this variety of menus on intake needs to be tested

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Not Eating Enough: Overcoming Underconsumption of Military Operational Rations over a period of time. In addition, carefully designed menu rotation studies that incorporate current understanding of the impact of variety, sensory specific satiety, temporal habituation patterns, energy density, the fat and fiber content of foods, and palatability on intake and body weight would provide directly relevant information (cf., Jordan et al., 1981; Kissileff, 1984; Levine and Billington, 1994; Porikos et al., 1977, 1982; Prewitt et al., 1991; Rolls, 1986; Rolls and Hetherington, 1989; Rolls et al., 1981, 1992). In summary, the problem of underconsumption from the perspective of those scientists involved with the food development and testing aspect of rations is that, despite significant efforts to test operational rations and measure their acceptability in the field over the last 10 years, there continues to be generalized weight loss when compared to garrison feeding studies even with the same MRE rations (Hirsch and Kramer, 1993; see Table 1-2). Thus, any review of the problem must include situational factors, such as environment, social settings, logistics, and temporal considerations, as well as perceptions or image of ration acceptability, and the possible interactions of all of these on consumption behavior. When Does Soldier Physical Performance Decline as a Result of Lowered Consumption? True underconsumption of food, in the face of continuing or increased expenditures of body energy stores, leads to weight loss. A loss of body weight, over time, thus appears to be the easiest guide for quantifying dietary underconsumption. However, for an accurate evaluation of weight loss data, it is important to know the changes in body composition that account for the lost weight. As discussed in previous CMNR reports (IOM, 1992a, 1993), different combinations in the complex relationships between dietary intake and energy expenditure can result in widely different forms of weight loss. As examples: Initially, simple starvation produces primarily losses of fluids, electrolytes, and small amounts of lean body mass and body fat, but then the body begins to derive virtually all of its energy needs from its fat stores, while using every possible metabolic method to conserve body nitrogen. Weight losses due to acute disease or trauma are associated initially with predominant losses of body muscle mass because of the acute phase reaction. This loss of muscle mass may be accompanied by losses in water, electrolytes, and fat. Weight losses associated with extreme energy expenditures during periods of food restriction (such as in U.S. Army Ranger training [Moore et al., 1992; Shippee et al., 1994]) are associated with losses of body fat, as well as with losses of body water and muscle mass.

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Not Eating Enough: Overcoming Underconsumption of Military Operational Rations Abrupt weight losses (within 24–48 hours) associated with high energy expenditures in hot, humid environments or protective clothing are due mainly to acute losses of body fluid and electrolytes. In assessing the degree of weight loss needed to induce measurable decrements in physical performance, Karl E. Friedl (see Chapter 14 in this volume; see also Table 1-2) reviewed data from a number of historical situations and studies, as well as data recently generated in separate studies of Scandinavian and U.S. Army Ranger trainees. There were some similar, overall conclusions that could be drawn from these diverse studies and weight loss situations: decrements in physical performance were not evident with minor degrees of weight loss or losses primarily of body fat. In studies conducted at the U.S. Army Ranger Training School (see Chapter 14 in this volume), decrements in physical performance occurred when weight losses of 10 to 15 percent were recorded over the 6 to 8 weeks of this intensive training program. Data from these studies cannot be directly applied to other military situations because Rangers in training in the Ranger School are highly motivated, thus these results may not be indicative of what can be expected from regular military units. The rate of weight loss in this situation must be taken into consideration. Weight losses of as little as 3 to 5 percent in 24 to 48 hours or less are primarily due to dehydration and will result in reductions in performance (see for example Altman and Fisher, 1986). Weight losses of 6 to 10 percent in a similar time period are potentially debilitating and may adversely affect the health of individuals. Therefore, when evaluating the effects of underconsumption of operational rations and resulting weight loss, it is necessary to eliminate dehydration as a factor and be concerned with well-hydrated individuals in assessing the effect of weight loss on performance. The rate of weight loss is also an important consideration in healthy and adequately hydrated individuals and is primarily related to the energy deficit. An approximate calculation is that a deficit of 3,500 calories equates to 1 lb of weight loss in overweight individuals. Therefore, extreme rates of weight loss in the presence of adequate hydration are indicative of severe underconsumption. A soldier of 160 lb body weight losing 10 percent of body weight or 16 lb in 2 weeks (14 days) would be experiencing a calorie deficit of approximately 16 x 3,500 divided by 14, or approximately 4,000 kcal/d. A similar loss in 4 weeks (28 days) represents an approximate daily deficit of 2,000 kcal/d; 8 weeks (56 days), 1,000 kcal/d deficit; and over 16 weeks (112 days), a 500 kcal/d deficit. Physically fit soldiers with less body fat than the usual, somewhat overweight individual would experience less fat loss and more reduction in lean body mass as weight loss progresses (see discussion in Altman and Fisher, 1988; Vanderveen et al., 1977). Therefore, the fit soldier is likely to have a reduction in performance capability related to the reduction in lean body mass similar to the studies with lean Gambian laborers, where

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Not Eating Enough: Overcoming Underconsumption of Military Operational Rations changes in body weight were mirrored by changes in fat-free mass, and fat-free mass was significantly correlated with physical work performance (Diaz et al., 1991). Workers in less developed countries where energy deficits are common during certain seasons voluntarily reduce their physical activity to compensate for the reduced energy intake and thus help retain lean body mass (Scrimshaw and Young, 1989). There is the suggestion from the data on Ranger Training School (Moore et al., 1992; Shippee et al., 1994; see Chapter 14 in this volume) that body weight loss of less than 10 percent in hydrated individuals may not significantly reduce physical performance. However, concern arises with continued energy deficits that may occur if troops are redeployed after losing 5 to 10 percent of their body weight and before having an opportunity to regain this lost weight. If inadequate energy intake continues and further weight loss occurs, performance deficits can be expected. In addition, voluntary physical activity will likely be reduced, and situations that demand high energy output may result in reduced ability to perform (Scrimshaw and Young, 1989). A number of studies have shown that the work productivity of semi-starved laborers could be increased markedly by supplementing their energy intake (Diaz et al., 1991; Viteri, 1971; Viteri and Torun, 1975; see also reviews by Conzolazio, 1983; Spurr, 1986, 1990). Weight losses in some of the historical studies were also complicated, undoubtedly, by deficiencies of certain nutrients, such as individual vitamins and minerals. Iron deficiency anemia, for example, induces decrements in physical performance (Edgerton et al., 1979; Finch and Huebers, 1982; Gardner et al., 1977) that can be reversed by iron supplementation (Edgerton et al., 1979). Multiple variables are known to complicate the evaluation of physical performance during periods of weight loss. Measured decrements in physical performance vary with the test procedure being used. Decrements in U.S. Ranger performance were best demonstrated by the incremental dynamic lift, a maximal lift capacity test (Moore et al., 1992). Load-lifting capability fell progressively by an average of 30 to 40 lb as Ranger training progressed to the third and fourth periods. The magnitude of performance decline correlated well with the percentage of weight lost by individual soldiers. In this study, a higher correlation was evident when decrements in lift capability were compared to losses in fat-free mass. In contrast, handgrip strength failed to show measurable decrements in the Rangers, even in the face of high percentages of body weight loss. Recently developed tests of jumping ability tend to yield performance data comparable to those generated by load-lifting tests (see Friedl, Chapter 14 in this volume). Physical performance tested during prolonged, continuous efforts, such as marching, jogging, or cross-country skiing, can give different results from studies using acute tests of strength. Some of these differences may be due to the type of muscle fibers being affected by the weight loss, that is, fast-twitch versus slow-twitch fibers. And some differences may be dependent on the

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Not Eating Enough: Overcoming Underconsumption of Military Operational Rations is strongly influenced by their hedonic attributes, although this relationship has not been carefully examined in field studies. In summary, the key points regarding fluid consumption and fluid related energy intake among troops in the field are: (1) improve hedonic qualities and variety of beverages supplied in the field to increase fluid intake, (2) optimize social settings in the field (e.g., mealtimes) to enhance fluid intake, (3) increase the convenience of obtaining water in the field, (4) encourage officers to promote increased fluid consumption among troops, and (5) conduct further research on the factors that influence fluid consumption and on the use of fluids to enhance energy intake. Biological Rhythms and Timing In Chapter 19 of this volume, Franz Halberg and colleagues discuss the influence of alterations in the diurnal pattern of food intake on physiologic functions of the body. In particular, Halberg's work has shown that the ingestion of a single daily meal in the evening promoted better weight maintenance than one consumed in the morning. A careful examination of meal timing in relation to the daily performance cycle in military personnel in the field might thus reveal if meal timing might be useful in optimizing body weight and performance. NEW CHANGES IN MILITARY OPERATIONAL RATIONS AND FIELD FEEDING Ration Evolution Development and testing of military operational rations has been an ongoing component of the military, and the use of nutritional standards for rations has been in place since World War II (for a review see Schnakenberg, Chapter 6 in this volume). All military rations are expected to meet the Military Recommended Dietary Allowances (MRDAs) (see AR 40-25, 1985) with the exception of restricted rations, which are currently the Ration, Lightweight; the Long Range Patrol Food Packet; and the Survival General Purpose, Food Packet. There are also separate specifications for these restricted rations, which are provided to sustain soldiers for no more than 10 days. Testing of military operational rations is prescribed in procedures and policies approved by the Office of the Surgeon General (OTSG) of the Army and is conducted jointly by USARIEM and the Sustainability Directorate at NRDEC. The MRDAs (included in AR 40-25, 1985) define both the recommended allowances for evaluating what people should consume and nutritional standards for development and procurement of the ration. However, the criteria

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Not Eating Enough: Overcoming Underconsumption of Military Operational Rations for testing rations are not specified, and USARIEM has had a major role in their development, as did the OTSG of the Army. Prior rations have included the K Ration in World War II and the C Ration (Meal, Combat Individual) in tin cans during World War II and Korea (see Schnakenberg, Chapter 6 in this volume for a more detailed history). The MRE ration was developed to replace the C Ration in the 1970s and 1980s and can be used for up to 21 days (U.S. Department of the Army, 1995). Many constraints exist in developing rations (see Darsch and Brandler, Chapter 7 in this volume). These constraints include acceptance, nutrition, wholesomeness, productivity, cost, sanitation, cultural appropriateness, variety, usage in a variety of environments, the need for withstanding air drops, shelf life equal to or greater than 3 years, minimal weight and size, and the capacity to self-heat and be assembled in modules tailored to the ration needed. In addition, the packaging must be protective in response to nuclear, biological, and chemical threats during war. Finally, there are performance enhancement characteristics that may affect the formulation of specific components (IOM, 1994). The program of continuous field improvement is reviewed in depth for all classes of rations by Gerald A. Darsch and Philip Brandler in Chapter 7 and Edward Hirsch in Chapter 9 of this volume. A review of the ration types is included earlier in this chapter. A new combination, the Unitized Group Ration (UGR), has been developed to simplify logistics of ordering and meal preparation in the field. The UGR uses components of the A Ration (without the perishables), the B Ration, the T Ration, and additional brand-name items combined in a unified system. Fifteen breakfast and 30 lunch/dinners are available. The UGR increases field feeding efficiency and reduces the number of items that a cook has to order to get the necessary items for a meal. Based on direct feedback from Desert Shield/Storm, the OTSG of the Army, and the CMNR, an increasing emphasis is being placed on nutritional labeling and nutrition information on operational rations. Guidelines are now being developed to provide appropriate consumer-oriented information. In the future, the goals are to develop self-heating rations with "fresh" quality yet shelf-stable and suitable for both individual and group feeding. Pending further approval, a self-heating group meal is in the planning stages; the meal module would include all accessories, be modularized similar to the UGR, but provide food for 18 soldiers. This concept has been called "Kitchens in a Carton." In summary, military operational rations are under almost continual revision. Ration developers are concerned to provide the best possible product for their consumers and at the same time be cognizant of the factors related to packaging, shelf-life, transport, and distribution. New developments such as shelf-stable bread products and the flameless ration heater will significantly broaden the scope of food products available for individual rations.

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Not Eating Enough: Overcoming Underconsumption of Military Operational Rations The Current Situation with Army Field Feeding Some of the major problems faced by the Army with feeding troops in the field include logistics, time, the quality of the food preparation and packaging, the lack of hot/cold alternatives with certain food items, and the lack of cooks in the forward areas. Added to these problems are the realities of combat itself. The MRE has some advantages in these circumstances, but when it does not include a flameless heater, lack of hot foods is still a significant deterrent to energy intake (for a discussion, see Motrynczuk, Chapter 4 in this volume). The logistics of supply may thus play a role in underconsumption of rations. The military feeding system in the field in the recent past, based on Army field feeding policy, has relied primarily on MREs and T Rations unless field kitchens were accessible. The policy was that commanders should provide soldiers with two T Rations per day and one A or B meal every 3 days. The recent Desert Shield/Storm conflict demonstrated that forward units might well not be supplied with even T Rations for periods of up to 60 days. This situation, in many cases, was the commander's decision, as the commander's responsibility according to policy was to provide soldiers with three quality meals per day, Mission, Enemy, Terrain, Troops, and Time (METT-T) dependent. Thus, long-term consumption of the MREs and any supplemental packs was a frequent occurrence depending on the scenario and the distance from battalion support services. In this environment, depending on time to reach the forward lines, hot meals in the form of T Rations might take 6 to 10 hours, and availability of hot fluids was limited to what the soldier could heat on his own. Thus, the logistics of supply and the system for field food preparation becomes extremely important in long-term support. In response to the problems encountered in Desert Shield/Storm, a new strategy for field feeding was developed that will provide soldiers with at least one cook-prepared meal (A or B Rations3) everyday and has now been approved by the Army Chief of Staff (Decision to Increase the Number of Military Cook Personnel, unpublished Army doctrine, June 1992). The major changes will be to have an enhanced company-level field feeding truck with two cooks, which will provide hot meals and perishable foods on a daily basis and be able to follow the unit on maneuvers. These field kitchens will be supervised by a foodservice technician at the brigade level who will develop the feeding plan for brigade-size exercises and ensure that the ration fits the unit scenario. This procedure will allow planned variety and provide a specific individual who is responsible for the meal planning. Significant efforts have thus been put forward to improve the component that supply and logistics has in affecting underconsumption of the ration. 3   A Rations are cook-prepared from fresh or perishable foods; B Rations are cook-prepared from canned or dehydrated foods.

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Not Eating Enough: Overcoming Underconsumption of Military Operational Rations Scenario in the Future The plan for the future as described by CW4 Peter Motrynczuk (see Chapter 4 in this volume for summary) is to add three more cooks per battalion and to use all cooks in new ways. The plan is to put small mess teams forward; one of these two-person teams will be a soldier with a grade of E-5 with some cooking experience. They will do limited food preparation forward and will have equipment and support to do it with Kitchen Company Level Field Feeding-Enhanced (KCLFF-E) equipment and a high-mobility vehicle (HMV). The equipment forward includes a sanitation center (SC) with materials for preparation and cleanup of B and some A Rations. This center is a component of the mobile kitchen trailer (MKT) with a new container kitchen and a generator to minimize preparation time, to allow food refrigeration, and to permit water storage. Cooks remain in the battalion field training area to do food preparation. Equipment improvements will be made at this level as well. It is hoped that by having the cooks forward with the assault companies it will be possible to customize food preparation to better fit troops' needs. This proposal is an example of tailoring both the food and the situation to each other, and then adjusting the fit. In summary, proposed changes in the number and location of Army cooks and their support vehicles may greatly reduce the present logistical difficulties in providing hot meals to soldiers. The improvements outlined by CW4 Peter Motrynczuk are scheduled for implementation in early 1996 and will also allow increased use of a wider variety of food items, including fresh foods. PROPOSED PLAN OF ACTION BY NRDEC The research proposal by Edward Hirsch (see Chapter 22 in this volume) is designed to show if certain manipulations in the way troops are fed in the field will lead to increased ration consumption. The proposed manipulations include using a new ration, premarketing the ration system, providing a social setting for the eating situations, and introducing more variety in the system. Other suggested manipulations are to prevent some of the trauma frequently associated with deployment, provide scheduled meals and snacks, create a protected environment for feeding, provide easy ways to heat the ration, and ensure adequate fluid intake. The proposal suggests that company-sized units might be exposed to the variable individually and food intake measured relative to energy expenditure. This demonstration would involve the use of approximately a battalion of troops and involve considerable data collection by a number of investigators. The CMNR is concerned that several of the proposed manipulations may produce an improvement, but provide little data as to whether or not implementation of these changes would result in adequate

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Not Eating Enough: Overcoming Underconsumption of Military Operational Rations intake of the modified ration system. The incremental effects of any of these manipulations could not be adequately evaluated, and it might not be possible to recommend a field feeding system that did or did not provide assurance of adequate consumption to meet energy needs. Instead such a program should first review the data on eating behavior from both military and civilian institutional studies. The best results from this review could be used to construct a multifactorial model concerning the importance of such variables as variety, meal schedules, snacks, feeding environment, social influences, and convenience of food preparation. Such a model would provide a basis for carefully controlled pilot studies to obtain a potential measure of the influence of these variables on intake. From these pilot studies, hypotheses could be constructed utilizing the most likely variables. Those variables that are judged feasible in a military operation could be more effectively tested. A multifactorial modeling approach could thus provide a rationale for obtaining military field test units. The resultant data could be used as a guide to field commanders in utilizing the strategies developed for a field feeding doctrine. Although the Army has devoted a significant amount of effort to ration development, less consideration has been given to the effects of situational and environmental factors that may have a significant impact on consumption. The stressful environment of the field, particularly combat, certainly impacts on ration consumption, and there may be higher acceptance of certain ration items than others under those conditions. A program for marketing or educating soldiers about the military operational ration and its importance to their performance may be important, particularly when it is known that negative comments from peers, superiors, media, and others can help establish a negative image of military combat rations and thus discourage consumption. Underconsumption of military operational rations may only be a problem if it has negative impact on physical and cognitive performance. Long-term or repeated usage of rations may result in more significant weight losses and thus may have the potential for larger effects on physical or cognitive performance. REFERENCES Adolph, E.F., and J.H. Wills 1947. Thirst. Pp. 241–253 in Physiology of Man in the Desert, E.F. Adolph and Associates, eds. New York: Interscience Publishers, Inc. Adolph, E.F., A.H. Brown, D.R. Goddard, R.E. Gosselin, J.J. Kelly, G.W. Molnar, H. Rahn, A. Rothstein, E.J. Towbin, J.H. Wills, and A.V. Wold 1947. The Physiology of Man in the Desert. New York: Interscience Publishers, Inc. Altman, P.L., and K.D. Fisher 1986. Research Opportunities in Nutrition and Metabolism in Space. Bethesda, Md.: Life Sciences Research Office, Federation of American Societies for Experimental Biology. AR (Army Regulation) 40-25 1985. See U.S. Departments of the Army, the Navy, and the Air Force.

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Not Eating Enough: Overcoming Underconsumption of Military Operational Rations Bass, D.E., C.R. Kleeman, M. Quinn, A. Henschel, and A.H. Hegnauer 1955. Mechanisms of acclimatization to heat in man. Med. Anal. Rev. 34:323–380. Beisel, W.R. 1991. Nutrition and infection. Pp. 507–542 in Nutritional Biochemistry and Metabolism with Clinical Applications, 2nd ed., M.C. Linder, ed. New York: Elsevier. Belk, R.W. 1975. Situational variables and consumer behavior. J. Consum. Res. 2:157–164. Berry, S.L., W.W. Beatty, and R.C. Klesges 1985. Sensory and social influences on ice cream consumption by males and females in a laboratory setting. Appetite 6:41–45. Booth, D.A., J. Fuller, and V. Lewis 1981. Human control of body weight: Cognitive or physiological? Some energy-related perceptions and misperceptions. Pp. 305–314 in The Body Weight Regulatory System: Normal and Disturbed Mechanisms, L.A. Cioffi, W.P.T. James, and T.B. Van Itallie, eds. New York: Raven Press. Cardello, A.V. 1994. Consumer expectations and their role in food acceptance. Pp. 253–297 in Measurement of Food Preferences, H.J.H. MacFie and D.M.H. Thompson, eds. Glasgow: Blackie Academic and Professional. Cardello, A.V., and F.M. Sawyer 1992. Effects of disconfirmed consumer expectations on food acceptability. J. Sensory Studies 7:253–277. Conger, J.C., A.J. Conger, P.R. Costanzo, K.L. Wright, and J.A. Matter 1980. The effect of social cures on the eating behavior of obese and normal subjects. J. Pers. 48:258–271. Consolazio, C.F. 1983. Nutrition and performance. Prog. Food Nutr. Sci. 7(1–2):29–42. Cornell, C.E., J. Rodin, and H. Weingarten 1989. Stimulus induced eating when satiated. Physiol. Behav. 45:695–704. de Castro, J.M. 1990. Social facilitation of duration and size but not rate of the spontaneous meal intake of humans. Physiol. Behav. 47:1129–1135. 1994. Family and friends produce greater social facilitation of food intake than other companions. Physiol. Behav. 56:445–455. de Castro, J.M., and E.M. Brewer 1992. The amount eaten in meals by humans is a power function of the number of people present. Physiol. Behav. 51:121–125. de Castro, J.M., and E.S. de Castro 1989. Spontaneous meal patterns in humans: Influence of the presence of other people. Am. J. Clin. Nutr. 50:237–247. de Graaf, C., A. Schreurs, and Y.H. Blauw 1993. Short-term effects of different amounts of sweet and nonsweet carbohydrates on satiety and energy intake. Physiol. Behav. 54:833–843. Diaz, E., G.R. Goldberg, M. Taylor, J.M. Savage, D. Sellen, W.A. Conward, and A.M. Prentice 1991. Effects of dietary supplementation on work performance in Gambian laborers. Am. J. Clin. Nutr. 53:803–811. Duncan, K.H., J.A. Bacon, and R.L. Weinsier 1983. The effects of high and low energy density diets on satiety, energy intake, and eating time of obese and nonobese subjects. Am. J. Clin. Nutr. 37:763–767. 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.

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Not Eating Enough: Overcoming Underconsumption of Military Operational Rations Edgerton, V.R., G.W. Gardner, Y. Ohira, K.A. Gunawardena, and B. Senewiratne 1979. Iron-deficiency anemia and its effect on worker productivity and activity patterns. Br. Med. J. 2:1546–1549. 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, with and without a supplemental pack in a cold environment. Technical Report T18–89. Natick, Mass.: U.S. Army Research Institute of Environmental Medicine. Edwards, J.S.A., E.W. Askew, N. King, C.S. Fulco, R.W. Hoyt, and J.P. DeLany 1991. An assessment of the nutritional intake and energy expenditure of unacclimatized U.S. Army soldiers living and working at high altitude. Technical Report T10–91. Natick, Mass.: U.S. Army Research Institute of Environmental Medicine. Engell, D. 1988. Interdependency of food and water intake in humans. Appetite 10:133–141. 1993. Effects of water intake on food palatability and intake [abstract]. Appetite 20:149. Engell, D., and E. Hirsch 1991. Environmental and sensory modulation of fluid intake in humans. Pp. 382–388 in Thirst: Physiological and Psychological Aspects, D.J. Ramsay and D.A. Booth, eds. London: Springer-Verlag. Engell, D.B., D.E. Roberts, E.W. Askew, M.S. Rose, J. Buchbinder, and M.A. Sharp 1987. Evaluation of the Ration, Cold Weather during a 10-day cold weather field training exercise. Technical Report TR-87/030. Natick, Mass.: U.S. Army Natick Research, Development and Engineering Center. Evans, W.J. 1993. Exercise and protein metabolism. World Rev. Nutr. Diet. 71:21–33. Evans W.J., and V.A. Hughes 1985. Dietary carbohydrate and endurance exercise. Am. J. Clin. Nutr. 41:1146–1154. Finch, C.A., and H. Huebers 1982. Perspectives in iron metabolism. N. Engl. J. Med. 306:1520–1528. Gardner, G.W., V.R. Edgerton, B. Senewiratne, R.J. Barnard, and Y. Ohira 1977. Physical work capacity and metabolic stress in subjects with iron deficiency anemia. Am. J. Clin. Nutr. 30:910–917. Goldman, S.J., C.P. Herman, and J. Polivy 1991. Is the effect of a social model on eating attenuated by hunger? Appetite 17:129–140. Hargreaves, M. 1991. Carbohydrates and exercise. J. Sports Sci. 9:17–28. Hirsch, E., and F.M. Kramer 1993. Situational influences on food intake. Pp. 215–243 in Nutritional Needs in Hot Environments, B.M. Marriott, ed. A report of the Committee on Military Nutrition Research, Food and Nutrition Board, Institute of Medicine, Washington, D.C.: National Academy Press. 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 TR-85/035. Natick, Mass.: U.S. Army Natick Research and Development Center. Hugstad, T.P., C.S. Mayer, and T.W. Whipple 1975. Consideration of context differences in product evaluation and market segmentation. J. Acad. Marketing Sci. 3:42. IOM (Institute of Medicine) 1992a. Body Composition and Physical Performance. A report of the Committee on Military Nutrition Research, Food and Nutrition Board. Washington, D.C.: National Academy Press.

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Not Eating Enough: Overcoming Underconsumption of Military Operational Rations 1992b. Letter report: Calorie-dense rations. In Committee on Military Nutrition Research Activity Report 1986–1992. A report of the Committee on Military Nutrition Research, Food and Nutrition Board. Washington, D.C.: National Academy Press. 1993. Review of the Results of Nutritional Intervention, Ranger Training Class 11/92 (Ranger II). A report of the Committee on Military Nutrition Research, Food and Nutrition Board. Washington, D.C.: National Academy Press. 1994. Food Components to Enhance Performance. A report of the Committee on Military Nutrition Research, Food and Nutrition Board. Washington, D.C.: National Academy Press. Jenkins, D.J.A., T. Wolever, V. Vuksan, F. Brighenti, S.C. Cunnane, A.V. Rao, A.L. Jenkins, G. Buckley, R. Patten, W. Sinder, P. Corey, and R.G. Josse 1989. Nibbling versus gorging: Metabolic advantages of increased meal frequency. New Engl. J. Med. 321:929–934. Jones P.J.H., I. Jacobs, A. Morris, and M.B. Ducharme 1993. Adequacy of food rations is soldiers during as arctic exercise measured by doubly labeled water. J. Appl. Physiol. 75:1790–1797. Jordan, H.A., L.S. Levitz, K.L. Utgoff, and H.L. Lee 1981. Role of food characteristics in behavioral change and weight loss. J. Am. Diet. Assoc. 79:24–29. Kalick, J. 1992. The effect of consumer-oriented packaging designs on acceptance and consumption of military rations. Technical Report TR-92/034. Natick, Mass.: U.S. Army Natick Research, Development and Engineering Center. Kark, R., R. Johnson, and J. Lewis 1946. Defects in pemmican as an emergency ration for infantry troops. War Med. 8:345–352. Kissileff, H.R. 1984. Satiating efficiency and a strategy for conducting food loading experiments. Neurosci. Biobehav. Rev. 8:129–135. Kissileff, H.R., L.P. Gruss, J. Thornton, and H.A. Jordan 1984. The satiating efficiency of foods. Physiol. Behav. 32:319–332. Kramer, F.M., J. Edinberg, S. Luther, and D. Engell 1989. The impact of food packaging on food consumption and palatability. Paper presented at Association for Advancement of Behavior Therapy, Washington, D.C. Lemon, P.W.R. 1991. Effect of exercise on protein requirements. J. Sports Sci. 9:53–70. Lester, L.S., F.M. Kramer, J. Edinberg, S. Mutter and D.B. Engell 1989. 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 TR-90/008L. Natick, Mass.: U.S. Army Natick Research, Development and Engineering Center. Lester, L.S., L.L. Lesher, M. Salomon, D.B. Engell, S.L. Dewey, J.L. Ward II , C. Thomas, and J. Kalick 1993. Nutritional and hedonic consequences of consuming the Meal, Ready-to-Eat (MRE) VIII or the Soldier Enhancement Program (SEP) MRE. Technical Report TR-93/015. Natick, Mass.: U.S. Army Natick Research, Development and Engineering Center. Levine, A.S., and C.J. Billington 1994. Dietary fiber: Does it affect food intake and body weight? Pp. 191–200 in Appetite and Body Weight Regulation: Sugar, Fat, and Macronutrient Substitutes, J. Fernstrom and G. Miller, eds. Boca Raton, Fla.: CRC Press. Mason, V.C., A.I. Meyer, and M.V. Klicka 1982. Summary of operational rations. Technical report TR-82/013. Natick, Mass.: U.S. Army Natick Research and Development Laboratories.

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Not Eating Enough: Overcoming Underconsumption of Military Operational Rations McArdle, W.D., F.I. Katch, and V.L. Katch 1991. Exercise Physiology: Energy, Nutrition, and Human Performance, 3rd ed. Philadelphia/London: Lea & Febiger. McClellan, W.S., and E.F. Dubois 1930. Clinical calorimetry XLV. Prolonged meat diets with a study of kidney function and ketosis. J. Biol. Chem. 87:651–668. Miller, K., And J. Ginter 1979. An investigation of situational in brand choice behavior and attitude. J. Marketing Res. 16:111–123. Moore-Ede, M.C. 1986. Physiology of the circadian timing system: Predictive versus reactive homeostasis. Am. J. Physiol. 250:735–752. Moore, R.J., K.E. Friedl, T.R. Kramer, L.E. Martinez-Lopez, R.W. Hoyt, R.T. Tulley, J.P. DeLany, E.W. Askew, and J.A. Vogel 1992. Changes in soldier nutritional status and immune function during the Ranger training course. Technical Report T13-92, AD A257 437. Natick, Mass.: U.S. Army Research Institute of Environmental Medicine. NLABS (U.S. Army Natick Research and Development Laboratories) 1983. Operational rations current and future of the Department of Defense. Natick, Mass.: U.S. Army Natick Research and Development Laboratories. NRC (National Research Council) 1989. Recommended Dietary Allowances, 10th ed. Report of the Subcommittee on the Tenth Edition of the RDAs, Food and Nutrition Board, Commission on Life Sciences. Washington, D.C.: National Academy Press. Pavlou, K.M. 1993. Energy needs of the elite athlete. World Rev. Nutr. Diet 71:9–20. Phinney, S.D., B.R. Bistrian, W.J. Evans, and G.L. Blackburn 1983. The human metabolic response to chronic ketosis without caloric restriction: Preservation of submaximal exercise capability with reduced carbohydrate oxidation . Metabolism 32:769–776. Popper, R., E.S. 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 TR-87/027. Natick, Mass.: U.S. Army Natick Research, Development and Engineering Center. Porikos, K.P., G. Booth, and T.B. Van Itallie 1977. Effect of covert nutritive dilution on the spontaneous intake of obese individuals: A pilot study. Am. J. Clin. Nutr. 30:1638–1644. Porikos, K.P., M.F. Hesser, and T.B. Van Itallie 1982. Caloric regulation in normal weight men maintained on a palatable diet of conventional foods. Physiol. Behav. 29:293–300. Prewitt, T.E., D. Schmeisser, P.E. Bowen, P. Aye, T.A. Dolecek, P. Langenberg, T. Cole, and L. Brace 1991. Changes in body weight, body composition, and energy intake in women fed high- and low-fat diets. Am. J. Clin. Nutr. 54(2):304–310. Rolls, B.J. 1986. Sensory-specific satiety. Nutr. Rev. 44:93–101. Rolls, B.J., and M. Hetherington 1989. The role of variety in eating and body weight regulation. Pp. 63–73 in Nutrition in the '90s: Current Controversies and Analysis, G.E. Gaull, F.N. Kotsonis, and M.A. Mackey, eds. New York: Marcel Dekker, Inc. Rolls, B.J., and D.J. Shide 1992. The influence of dietary fat on food intake and body weight. Nutr. Rev. 50:283–290.

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Not Eating Enough: Overcoming Underconsumption of Military Operational Rations Rolls, B.J., E.A. Rowe, E.T. Rolls, B. Kingston, A. Megson, and R. Gunary 1981. Variety in a meal enhances food intake in man. Physiol. Behav. 26:215–221. Rolls, B.J., P.M. van Duijvenvoorde, and E.T. Rolls 1984. Pleasantness changes and food intake in a varied four-course meal. Appetite 5:337–348. Rolls, B.J., I.C. Fedoroff, J. Guthrie, and L.J. Laster 1990. Foods with different satiating effects in humans. Appetite 15:115–126. Rolls, B.J., D.J. Shide, N. Hoeymans, P. Jas, and A. Nichols 1992. Information about fat content of preloads influences energy intake in women [abstract]. Appetite 19:213. Rose, M.S 1989. Between-meal food intake for reservists training in the field. Technical Report T15-89. Natick, Mass.: U.S. Army Research Institute of Environmental Medicine. Rose, M.S., and D.E. Carlson 1986. Effects of A Ration meals on body weight during sustained field operations. Technical Report 2-87. Natick, Mass.: U.S. Army Research Institute of Environmental Medicine. Salter, C.A., D. Sherman, S. Adams, and K. Rock 1990. Feeding concept, military vs. civilian system. Technical Report TR-91/011. Natick, Mass.: U.S. Army Natick Research, Development and Engineering Center. Schutz, H.G. 1988. Beyond preference: Appropriateness as a measure of contextual acceptance of food. Pp. 115–134 in Food Acceptability, D.M.H. Thompson, ed. London: Elsevier Applied Science. Schutz, H.G., and F.J. Pilgrim 1958. A field study of monotony. Psychol. Rep. 4:559–565. Scrimshaw, N.S., and V.R. Young 1989. Adaptation to low protein and energy intakes. Hum. Organ. 48(1):20–30. Shaw, J. 1973. The Influence of Type of Food and Method of Presentation on Human Eating Behavior. Ph.D. Dissertation, University of Pennsylvania, Philadelphia. Sherif, M., and C.I. Hovland 1961. Social Judgment: Assimilation and Contrast Effects in Communication and Attitude Change. New Haven, Conn.: Yale University Press. Shippee, R., K. Friedl, T. Kramer, M. Mays, K. Popp, E.W. Askew, B. Fairbrother, R. Hoyt, J. Vogel, L. Marchitelli, P. Frykman, L. Martinez-Lopez, E. Bernton, M. Kramer, R. Tulley, J. Rood, J. DeLany, D. Jezior, and J. Arsenault 1994. Nutritional and immunological assessment of Ranger students with increased caloric intake. Technical Report T95-5. Natick, Mass.: U.S. Army Research Institute of Environmental Medicine. Siegel, P.S., and F.J. Pilgrim 1958. The effect of monotony on the acceptance of food. Am. J. Psychol. 71:756–759. Smutz, E.R., H.L. Jacobs, D. Waterman, and M. Caldwell 1974. Small sample studies of food habits: 1. The relationship between food preference and food choice in naval enlisted personnel at the Naval Construction Battalion Center, Davisville, Rhode Island. Technical Report TR-75-52-FSL. Natick, Mass.: U.S. Army Natick Research and Development Command. Spurr, G.B. 1986. Physical work performance under conditions of prolonged hypocaloria. Pp. 99–135 in Predicting Decrements in Military Performance Due to Inadequate Nutrition. A report of the Committee on Military Nutrition Research, Food and Nutrition Board, Commission on Life Sciences, National Research Council. Washington D.C.: National Academy Press. 1990. Physical activity and energy expenditure in undernutrition. Prog. Food. Nutr. Sci. 14:139–192.

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Not Eating Enough: Overcoming Underconsumption of Military Operational Rations Thomas, C.D., C.J. Baker-Fulco, T.E. Jones, N. King, D.A. Jezior, B.N. Fairbrother, and E.W. Askew 1993. Nutrition for health and performance: Nutritional guidance for military operations in temperate and extreme environments. Technical Note 93-3, AD 261 392. Natick, Mass.: U.S. Army Research Institute of Environmental Medicine. Tournier, A., and J. Louis-Sylvestre 1991. Effect of the physical state of a food on subsequent intake in human subjects. Appetite 16:17–24. USACDEC/USARIEM (U. S. Army Combat Developments Experimentation Center and U.S. Army Research Institute of Environmental Medicine) 1986. Combat Field Feeding System-Force Development Test and Experimentation (CFFS-FDTE). Technical Report CDEC-TR-85-006A. Vol. 1, Basic Report; vol. 2, Appendix A; vol. 3, Appendixes B through L. Fort Ord, Calif.: U.S. Army Combat Developments Experimentation Center. U.S. Department of the Army 1995. Memorandum for Deputy Chief of Staff for Logistics, Revision of Sole Source Meal, Ready-to-Eat Policy-Action Memorandum. June 21. Washington, D.C. U.S. Departments of the Army, the Navy, and the Air Force 1985. Army Regulation 40-25/Naval Command Medical Instruction 10110.1/Air Force Regulation 160-95. ''Nutrition Allowances, Standards, and Education." May 15. Washington, D.C. Vanderveen, J.E. T.H. Allen, G.F. Gee, and R.E. Chapin 1977. Importance of body fat burden on composition of loss in body mass of men [abstract]. Second International Congress on Obesity, October 23–26, Washington, D.C. Viteri, F.E. 1971. Considerations on the effect of nutrition on the body composition and physical working capacity of young Guatemalan adults. Pp. 350–375 in Amino Acid fortification of Protein Foods, N.S. Scrimshaw and A.M. Altshull, eds. Cambridge, Mass.: Massachusetts Institute of Technology Press. Viteri, F.E., and B. Torun 1975. Ingestion calorica and trabajo fisico de obreros agricolas en Gautemala. Efecto de la supplementation alimentaria y su lugar en los programs de salud. Bol. Off. Sanit. Panam. 78:58–74. Weingarten, H.P. 1984. Meal initiation controlled by learned cues: Basic behavioral properties. Appetite 5:147–158. Williams, D. 1993. Carbohydrate needs of elite athletes. World Rev. Nutr. Diet 71:34–60. Woods, S.C. 1991. The eating paradox: How we tolerate food. Psychol. Rev. 98:488–505. Woods, S.C., J.R. Vaselli, E. Kaestner, G.A. Szakmary, P. Milburn, and M.V. Vitello 1977. Conditioned insulin secretion and meal feedings in rats. J. Comp. Physiol. Psychol. 91:128–133. Wyant, K.W., H.L. Meiselman, and D. Waterman 1979. U.S. Air Force food habits study: Part I, Method and overview. Technical Report TR-79-041. Natick, Mass.: U.S. Army Natick Research and Development Command. Zajonc, R.B. 1965. Social facilitation. Science 149:269–274.