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Not Eating Enough: Overcoming Underconsumption of Military Operational Rations (1995)

Chapter: 8 An Overview of Dietary Intakes During Military Exercises

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Suggested Citation:"8 An Overview of Dietary Intakes During Military Exercises." Institute of Medicine. 1995. Not Eating Enough: Overcoming Underconsumption of Military Operational Rations. Washington, DC: The National Academies Press. doi: 10.17226/5002.
×

8
Overview of Dietary Intakes During Military Exercises

Carol J. Baker-Fulco1

Not Eating Enough, 1995

Pp. 121–149. Washington, D.C.

National Academy Press

INTRODUCTION

Nutrition influences how well a soldier can train and fight. An optimal diet may be helpful in delaying fatigue, improving performance during training or combat, and avoiding injuries, while certain nutrient deficiencies can seriously impair performance. Military rations provide for the nutritional needs of the majority of service members; unfortunately, what is provided is not always consumed. If soldiers do not consume adequate rations, mental and physical performance and morale may suffer.

The purpose of this chapter is to present an overview of results of many ration consumption studies conducted by the Military Nutrition Division

1  

Carol J. Baker-Fulco, Military Nutrition Division, U.S. Army Research Institute of Environmental Medicine, Natick, MA 01760-5007

Suggested Citation:"8 An Overview of Dietary Intakes During Military Exercises." Institute of Medicine. 1995. Not Eating Enough: Overcoming Underconsumption of Military Operational Rations. Washington, DC: The National Academies Press. doi: 10.17226/5002.
×

(MND) so that the Committee on Military Nutrition Research can put the issue of underconsumption of rations into perspective and determine what interventions are warranted. Is there really a problem? If so, is underconsumption a problem of such magnitude as to threaten health or performance, or is the problem mainly one of degrading morale or wasting of food dollars?

METHODS

MND conducts ration tests in the field, using troops in their usual environments while they perform their everyday military duties. Most ration studies are performed to assess the nutritional impact of a prototype or an improved version of an operational ration. Data have been collected mostly from men, ages 19 to 30 years. Mean body weights have ranged from 75 to 81 kg. Study durations have varied from 5 to 30 days, although most studies lasted 7 to 10 consecutive days. One major exception was the Combat Field Feeding System-Force Development Test and Experimentation (CFFS-FDTE) conducted in Hawaii in 1985, which recorded food intake on days 2, 3, 6, 7, 12, 13, 18, 19, 24, 25, 30, 31, 36, 37, 42, and 43 of a 44-d field exercise (USACDEC/USARIEM, 1986). In all of the other field studies summarized in this chapter, although the study duration varied, data was collected on consecutive days.

In studies when most food intake was obtained from military dining facilities or when hot meals were served in the field, the dietary intake data were usually collected by visual estimation. For this method, the test subject presented his or her tray to a data collector before sitting down to eat. The data collector recorded the food items and visually compared the portion sizes of foods on the subject's tray to a weighed standard of the same food. The data collectors were trained to estimate portion sizes to within 10 percent. After the meal, the test subject returned to the data collector, who recorded the quantity of food remaining on the tray. Foods consumed outside the dining facility were recorded by the subject on food records.

For studies of individual field rations, dietary intakes were also obtained by self-recorded food record. Cards that were precoded and printed with the menu items were provided to the subjects. The subject had only to circle the proportion of a serving consumed next to the appropriate menu item. There were separate prompts for recording canteens or cups of water. When it was important to determine water intake accurately, subjects were provided with graduated bottles or canteens to measure their fluid consumption. A food record is a reasonably accurate method of collecting food intake data because ration items are individually packaged, single serving-sized pouches or bars. When the test subjects were accessible, dietitians collected and reviewed the

Suggested Citation:"8 An Overview of Dietary Intakes During Military Exercises." Institute of Medicine. 1995. Not Eating Enough: Overcoming Underconsumption of Military Operational Rations. Washington, DC: The National Academies Press. doi: 10.17226/5002.
×

food records with the subjects daily. In some situations, the subjects were not accessible, and therefore, weekly log books were used.

LIMITATIONS

While the MND studies collectively represent dietary intakes in the military, they cannot be used to look at trends or changes in dietary intakes. Although the study samples often represented large segments of the military, they were not random samples of military personnel. The number of test subjects was often small, and data were often collected for only a few days at the beginning of a field exercise. The data should thus not be interpreted to represent usual dietary intakes of the populations studied. Rather, the data reflect the exact nature and quantity of individual foods consumed within defined periods of time. The data collected do not account for intraindividual variations due to day of the week (weekday or weekend) or season of the year. Many studies did not record or analyze intakes of commercial or nonration foods ("pogey bait"). In addition, the ration composition data are based on few samples and do not reflect losses that would occur due to prolonged storage.

RESULTS AND DISCUSSION

Dietary and Energy Intakes in Garrison

Table 8-1 shows typical energy, carbohydrate, and protein intakes of MND study groups in garrison. Garrison studies evaluate soldiers' intake patterns in a more free-living situation while they perform their daily jobs and eat at least some of their meals in the dining facility on post. The results in Table 8-1 of the Fort Lewis and the two Fort Devens studies differ from the figures published in the original technical reports (Szeto et al., 1987, 1988). These reports did not include foods consumed outside of the dining facility, nor did they present mean total dietary intakes. The daily means reported were totals of the mean breakfasts, mean lunches, and mean dinners of whichever study participants ate those meals. The data were subsequently reanalyzed for mean total dietary intakes and for foods consumed outside of the military dining facilities. The corrected data for these four studies are reported in Table 8-1.

Soldiers do not necessarily consume less in the field than in garrison. Energy intakes in garrison have ranged from 2,730 kcal at Fort Lewis to 3,260 kcal at Fort Devens. Except for a slightly lower energy intake by the Fort Lewis group, energy and protein intakes met Military Recommended Dietary Allowances (MRDAs) (AR 40-25, 1985). Energy intakes were relatively high

Suggested Citation:"8 An Overview of Dietary Intakes During Military Exercises." Institute of Medicine. 1995. Not Eating Enough: Overcoming Underconsumption of Military Operational Rations. Washington, DC: The National Academies Press. doi: 10.17226/5002.
×

TABLE 8-1 Mean Dietary Intakes of Military Men in Garrison

Year

Location

N

Study Duration (days)

Energy (kcal)

Carbohydrate (g)

Protein (g)

Reference

1986

Ft. Lewis

31

6

2,730

313

103

Szeto et al., 1987

1987

Ft. Devens

54

7

3,260

400

114

Szeto et al., 1988

1988

Ft. Devens

51

8

3,131

353

126

Szeto et al., 1989

1991

Ft. Chaffee*

32

30

2,901

358

125

Thomas et al., unpublished

* Ft. Chaffee garrison data consist of total dietary intakes of the control group for a 30-d Meal, Ready-to-Eat (MRE) study. This group consumed two meals in a dining facility. They were provided 1 MRE/d for consumption at the worksite.

C. D. Thomas et al., U.S. Army Research Institute of Environmental Medicine, Natick, Mass., unpublished data.

compared to a mean energy intake of 2,667 kcal for men aged 19 to 34 years in the 1985 Nationwide Food Consumption Survey-Continuing Survey of Food Intakes by Individuals (NFCS-CSFII) (USDA, 1986).

MND also has studied students in military academy or school situations, where the subjects were more restricted, were typically required to attend all meals in the dining facility, and generally were more physically active than when in their usual jobs. Results of these studies are shown in Table 8-2. Study populations have been cadets at West Point; students of the Noncommissioned Officer Academy at Fort Riley, Kansas; enlisted basic trainees at Fort Jackson, South Carolina; and Marine Officer Candidates at Quantico, Virginia. The high energy intakes reflect the high levels of physical activity inherent in the training schedules of these schools.

Dietary intakes in garrison and academy situations have been presented as a reference point with which to interpret intakes in the field. They show the relatively high energy intakes when service men are not in the field. Unwanted weight gain is often a problem in garrison, while weight loss is typically observed in field situations. Depending on the quantity of physical training and the ease of obtaining food, either undesirable weight loss or weight gain tend to occur in academy or school situations.

Suggested Citation:"8 An Overview of Dietary Intakes During Military Exercises." Institute of Medicine. 1995. Not Eating Enough: Overcoming Underconsumption of Military Operational Rations. Washington, DC: The National Academies Press. doi: 10.17226/5002.
×

TABLE 8-2 Mean Dietary Intakes of Military Men in Academy or Training Situations

Year

Location

N

Study Duration (days)

Energy (kcal)

Carbohydrate (g)

Protein (g)

Reference

1979

West Point

13

5

3,738

432

125

Kretsch et al., 1986

 

 

6

1986

NCO* Academy

43

8

3,199

387

124

Carlson et al., 1987

1988

Enlisted Basic

41

7

3,199

410

125

R.W. Rose et al., 1989

1990

West Point

11

7

3,564

482

130

Klicka et al., 1993

 

 

9

1990

Marine OCS

12

5

4,430

559

160

Baker-Fulco et al., 1992

 

 

1

1992

1991

Marine OCS

16

5

4,647

706

169

Baker-Fulco et al., 1994

 

 

2

* Noncommissioned Officer.

Officer Candidate School.

Dietary and Energy Intakes in the Field

Table 8-3 presents the abbreviations used for military operational rations and a brief description of the rations. Energy requirements during field exercises are probably as high as during the academy or school situations, yet much lower energy intakes were found (see Table 8-4). For most of these studies, the high end of the MRDA energy allowance range was used (i.e., 3,600 kcal) to assess adequacy. For the Fort Hood study, in which physical activities were only moderate, 3,200 kcal was selected as a better criterion.

The only field study group that met the energy allowance was the Fort Sill group. Due to a last-minute moratorium on the Meal, Ready-to-Eat (MRE), this group received three hot A Ration meals while engaged in sustained operations. Not only did they receive three hot meals, but because hot meals were trucked out at specific times, meal times were scheduled, and the troops were given ample time to eat. This is the only field study that showed a mean weight gain by the subjects. The Fort Sill study clearly illustrates the benefit of providing scheduled, hot meals.

Suggested Citation:"8 An Overview of Dietary Intakes During Military Exercises." Institute of Medicine. 1995. Not Eating Enough: Overcoming Underconsumption of Military Operational Rations. Washington, DC: The National Academies Press. doi: 10.17226/5002.
×

TABLE 8-3 Military Rations

Ration

Description*

A

Perishable, semi-perishable, and staple foods served in garrison dining facilities. A Rations require refrigeration facilities and trained cooks.

B

Canned or dried foods not requiring refrigeration but requiring trained cooks to prepare.

T (Tray Pack)

Fully cooked, canned foods requiring only reheating. Used when group feeding is possible, but trained cooks and refrigeration are not available.

MRE (Meal, Ready-to-Eat)

Individual operational ration. Three menus per day provide an average of 3,900 kcal. The MRE has gone through numerous revisions since introduction. The version number refers to date of packaging.

RCW (Ration, Cold Weather)

Individual operational ration designed for cold-weather operations. Consists of low-moisture foods to avoid freeze-thaw damage and contains less protein and sodium to conserve body water.

* For more detailed description of each ration, see Darsch and Brandler (Chapter 7 in this volume).

Most of MND's ration studies revealed a variable weight loss during field exercises. Although no ration group in the 1985 Hawaii study of the Combat Field Feeding System-Force Development Test and Experimentation (CFFS-FDTE) lost greater than 3 percent of initial body weight, many individuals lost more than 5 percent of body weight during the 44-d field exercise. Approximately 9 percent, 10 percent, and 17 percent of men in the 2:T Ration, 2:A Ration, and 1:T Ration groups, respectively, lost more than 5 percent of their initial body weight. Thirty-seven percent of the men in the 2:B & 1:MRE group lost greater than 5 percent body weight.

Although the energy intake of the Fort Hood group was lower than the allowance, the group, as a whole, maintained body weight. This relatively high energy intake was partly attributable to the widespread availability of commercial snack foods. Between-meal foods and fluids accounted for 25 percent of the total energy intake. Only 44 percent of the MRE meals were consumed (Rose, 1989).

The very low energy intakes seen in the Bolivia study were probably due to the effects of altitude-induced anorexia. Abrupt exposure to high altitudes often results in symptoms of acute mountain sickness. These symptoms include headache, anorexia, nausea, vomiting, and malaise, all of which can interfere with the desire to eat. Food intakes are usually reduced 10 to 50 percent during acute altitude exposure (Askew, 1993). However, even after the symptoms of acute mountain sickness subside, depressed food intakes persist (Baker et al.,

Suggested Citation:"8 An Overview of Dietary Intakes During Military Exercises." Institute of Medicine. 1995. Not Eating Enough: Overcoming Underconsumption of Military Operational Rations. Washington, DC: The National Academies Press. doi: 10.17226/5002.
×
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TABLE 8-4 Mean Dietary Intakes and Weight Loss of Military Men during Field Studies

Ration

Year

Environment and Location

N

Study Duration (days)

Energy (kcal)

Carbohydrate (g)

Protein (g)

Weight Loss (%)

Reference

A

1986

Temperate, Ft. Sill, OK

31

8

3,713

467

129

0.0

Rose and Carlson, 1986

2:A & 1:MRE

1985

Temperate, Hawaii

33

16 out of 44*

3,047

334

113

~1.3

USACDEC/USARIEM, 1986

2:T & 1:MRE

1985

Temperate, Hawaii

33

16 out of 44*

2,689

354

105

~1.4

USACDEC/USARIEM, 1986

1:T & 2:MRE

1985

Temperate, Hawaii

38

16 out of 44*

2,715

335

107

~2.1

USACDEC/USARIEM, 1986

MRE VI

1985

Temperate, Hawaii

167

2

2,445

254

98

NA

USACDEC/USARIEM, 1986

MRE VI

1986

Temperate, Camp Ethan Allen, VT

17

30

2,782

318

112

2.2

Askew et al., 1987

2:A or B & 1:MRE VI

1988

Hot, Ft. Hood, TX

?

8

3,056

404

113

1.0

M.S. Rose et al., 1989

2:B & 1:MRE VIII

1990

High altitude, Bolivia

35

15

2,140

244

97

2.0

Edwards et al., 1991

2:B & 1:MRE VIII + Suppl.§

1990

High altitude, Bolivia

32

15

2,265

271

100

2.0

Edwards et al., 1991

MRE XII

1991

Temperate, Ft. Chaffee, AR

32

30

2,901

358

125

4.8

Thomas et al., unpublished

*, The Combat Field Feeding System-Force Development Test and Experimentation (CFFS-FDTE) conducted in Hawaii in 1985, recorded food intake on days 2, 3, 6, 7, 12, 13, 18, 19, 24, 25, 30, 31, 36, 37, 42, and 43 of a 44-d field exercise; , NA, not available; , technical report did not report sample sizes of gender groups; §, the supplement group received approximately an additional 125 g of carbohydrate and 775 kcal/d in a food packet containing cookies, candies, bread and jellies, and nut-raisin mix; , C. D. Thomas et al., U.S. Army Research Institute of Environmental Medicine, Natick, Mass., unpublished data.

Suggested Citation:"8 An Overview of Dietary Intakes During Military Exercises." Institute of Medicine. 1995. Not Eating Enough: Overcoming Underconsumption of Military Operational Rations. Washington, DC: The National Academies Press. doi: 10.17226/5002.
×

1989). Mean weight losses in the Bolivia study were 2 percent of initial body weight for both the supplemented and control groups, consistent with body weight losses reported by other investigators for a 2-wk period at moderate altitude (Boyer and Blume, 1984; Fulco et al., 1985). The soldiers in this study were heavy equipment operators and not very physically active. Had they been required to perform the hard work typical of many high altitude field operations, weight losses may have been much greater.

MND's most recent ration study was a 30-d trial of the MRE conducted at Fort Chaffee, Arkansas. The control group for this study underwent the same training activities as the test group, but received two hot A Ration meals in a fixed dining facility on post and 1 MRE/d to be eaten at the worksite. The test group received 3 MREs/d. Both groups had scheduled meal times and were given ample time to eat. Flameless ration heaters were provided with the MREs. Because the MRE test group ate their breakfast and dinner rations at their bunks in the barracks, they avoided many of the situational factors that are thought to influence food consumption negatively (Hirsch and Kramer, 1993), such as they were protected from the elements, had ready access to potable water, and could wash their hands. Irregardless of this positive environmental situation, the test group consumed about 450 kcal less than the control group, and both the test and the control groups lost weight. The MRE test group lost a mean of 4.8 percent of initial body weight (9.1 lb or 4.1 kg) by day 30, while the control group lost a mean of 2.4 percent (4.3 lb or 2.0 kg).

The above studies show that soldiers typically do not consume enough rations during field operations to maintain body weight. For the most part, the longer the field study, the greater the weight loss. When more fresh foods and a greater variety of foods are offered, energy intakes are greater and weight losses are less. The presence of scheduled feeding periods, which occurs when hot foods are provided, enhances ration intakes.

Dietary and Energy Intakes During Cold Weather Field Training

Winter conditions in arctic and subarctic areas impose many constraints on the adequate feeding of troops. Freezing affects not only the ability to open ration packages but also the palatability and acceptability of the ration. All tasks take longer in cold-weather operations, leaving less time to prepare and consume food or beverages. Table 8-5 shows the results of cold-weather ration studies. Although energy intakes were higher in the cold-weather studies than what was observed in other field studies, they did not come close to the 4,500 kcal energy allowance for cold-weather operations. Based on the MRDA,

Suggested Citation:"8 An Overview of Dietary Intakes During Military Exercises." Institute of Medicine. 1995. Not Eating Enough: Overcoming Underconsumption of Military Operational Rations. Washington, DC: The National Academies Press. doi: 10.17226/5002.
×

TABLE 8-5 Mean Dietary Intakes of Military Men during Cold-Weather Training

Ratio

Year

Location

N

Study Duration (days)

Energy (kcal)

Carbohydrate (g)

Protein (g)

Weight Loss (%)

Reference

4:MRE

1986

New Hampshire

16

9

2,733

302

99

4.0

Roberts et al., 1987

4:MRE III

1988

MMWTC*

8

11

3,217

369

133

3.3

Morgan et al., 1988

31/2:MRE VIII

1989

Alaska

31

10

2,802

NA

NA

2.0

Edwards et al., 1989

MRE VIII + Suppl.

1989

Alaska

34

10

3,553

NA

NA

1.7

Edwards et al., 1989

MRE VIII + Suppl.

1990

Alaska

72–76

8

2,729

320

114

1.6

Edwards et al., 1990

RCW§

1986

New Hampshire

18

9

2,751

384

83

3.0

Roberts et al., 1987

RCW

1988

MMWTC

10

11

2,892

410

95

3.4

Morgan et al., 1988

RCW

1988

Alaska

16

8

2,891

386

92

3.1

Roberts et al., 1989

RCW

1990

Alaska

68–76

8

2,943

421

97

1.7

Edwards et al., 1990

2:T# &

1:MRE

1991

Alaska

37

10

3,271

375

134

1.1

King et al., 1992

*, Marine Mountain Warfare Training Center, Pickel Meadows, Calif.; , NA, not available; study mean not reported; , data reported as mean of days, not mean of individuals. There were 75 or 76 usable dietary records depending on study day. Weight change data reported for 72 subjects; §, Ration, Cold Weather, , data reported as mean of days, not mean of individuals. There were 69 to 76 usable dietary records depending on study day. Weight change data reported for 68 subjects; #, T Ration; see description of this ration in in Table 8-3.

Suggested Citation:"8 An Overview of Dietary Intakes During Military Exercises." Institute of Medicine. 1995. Not Eating Enough: Overcoming Underconsumption of Military Operational Rations. Washington, DC: The National Academies Press. doi: 10.17226/5002.
×

energy deficits ranged from approximately 950 to 1,770 kcal, and averaged 1,500 kcal for all studies.

The 1991 Alaska study (King et al., 1992) was the only cold-weather study that MND conducted in which hot meals were provided. Not unexpectedly, this study had one of the highest energy intakes and the least weight loss of any of the cold-weather tests.

Dietary and Energy Intakes of Military Women

Table 8-6 presents the energy, carbohydrate, and protein intakes of military women in garrison and in the field. Energy intakes ranged from 1,832 kcal at Fort Lewis to 2,592 kcal in enlisted basic training. All of the women studied had energy intakes greater than the 1985–1986 NFCS-CSFII results for women 19 to 34 years of age, which averaged 1,558 kcal (USDA 1987, 1988). The current MRDA for women is 2,000 to 2,800 kcal.

MND has conducted only two studies in the field that included women. The first study was a hot-weather study at Fort Hood, Texas, in which the women received two hot meals and had liberal access to commercial snack foods. The women (as did the men in this study), on average, maintained body weight. The other field study was conducted at high altitude in Bolivia. Again, a depression of food intakes was seen at high altitude; however, body weight losses averaged only 0.74 percent, which indicates that energy intakes were sufficient to provide for the women's physical activity.

Intentional Weight Loss

Some of the weight losses observed during field operations are intentional. Many soldiers use field exercises as opportunities to diet. When asked prior to a number of different studies about their desire to lose or gain weight, 12 to 86 percent of participants reported that they wanted to lose weight (Edwards et al., 1989; USACDEC/USARIEM, 1986). However, up to 26 percent of study populations expressed the desire to gain weight (King et al., 1992). Although MND usually saw a mean body weight loss in its studies, there was always a small proportion of soldiers who gained weight.

Carbohydrate

Perhaps of more concern than the energy deficit observed during field studies is the carbohydrate deficit. Carbohydrates are very important in a

Suggested Citation:"8 An Overview of Dietary Intakes During Military Exercises." Institute of Medicine. 1995. Not Eating Enough: Overcoming Underconsumption of Military Operational Rations. Washington, DC: The National Academies Press. doi: 10.17226/5002.
×

TABLE 8-6 Dietary Intakes of Military Women

Ration

Year

Environment and Location

N

Study Duration (days)

Energy (kcal)

Carbohydrate (g)

Protein (g)

Reference

Garrison

A

1987

Temperate, Ft. Lewis, WA

12

6

1,832

212

75

Szeto et al., 1987

Academy/Training

A

1979

Temperate, West Point, NY

54

5

2,454

284

84

Kretsch et al., 1986

A

1988

Hot, enlisted basic training, Ft. Jackson, SC

40

7

2,467

318

96

R.W. Rose et al., 1989

A

1990

Temperate, West Point, NY

86

5

2,314

325

79

Klicka et al., 1993

A

1993

Temperate, enlisted basic training, Ft. Jackson, SC

49

7

2,592

365

82

King et al., 1994

Field

2:B & 1:MRE

1988

Hot, Ft. Hood, TX

?*

8

2,343

328

82

M.S. Rose et al., 1989

2:B & 1:MRE

1990

High altitude, Bolivia

13

15

1,668

218

68

Edwards et al., 1991

* Technical report did not report sample size of gender groups.

Suggested Citation:"8 An Overview of Dietary Intakes During Military Exercises." Institute of Medicine. 1995. Not Eating Enough: Overcoming Underconsumption of Military Operational Rations. Washington, DC: The National Academies Press. doi: 10.17226/5002.
×

physically active population. Field operations typically involve repeated, short-duration, high-intensity activities that rely heavily on carbohydrate stores for energy (Saltin and Karlsson, 1971). In addition, soldiers frequently must perform extended activities of moderate intensity, such as road marches. Availability of carbohydrate fuels determines endurance during prolonged activities. Potentially contributing to carbohydrate depletion is an increased usage of muscle glycogen during exercise performed in hot environments (Fink et al., 1975), and glycogen usage is increased when individuals shiver in the cold (Jacobs et al., 1985). Muscle glycogen depletion can occur over repeated days of heavy activity (Costill et al., 1971). Failure to restore muscle and liver glycogen stores will result in fatigue and disorientation and may increase the risk of injury (Williams, 1988).

There is no MRDA for carbohydrate. Sports nutritionists recommend a diet of at least 8 g/kg of body weight per day for individuals working hard for several hours a day. This corresponds to a carbohydrate intake of 500 to 600 g or approximately 65 percent of total calories. A carbohydrate intake of 6 g/kg/d is considered sufficient for persons exercising for 1 hour or less per day. This level would equate to about 400 to 500 g of carbohydrate per day.

MND found mean carbohydrate intakes greater than 400 g in only four field studies. One of these studies was the Fort Sill study in which three hot A Ration meals were fed (mean carbohydrate intake, 467 g) (Rose and Carlson, 1986). Another study was the Fort Hood study in which two hot B Ration meals were provided (M.S. Rose et al., 1989). The other two studies were cold-weather studies in which the high-carbohydrate Ration, Cold Weather (RCW) was the sole ration provided (Edwards et al., 1990; Morgan et al., 1988). The RCW provides about 650 g of carbohydrate, while the MRE provides about 475 g of carbohydrate.

Protein

Although energy and carbohydrate intakes are generally lower than desired, mean protein intakes almost always approach the MRDA of 100 g for men and 80 g for women (Tables 8-4, 8-5, and 8-6). The MRDA levels are probably adequate, although they are not as generous as they may seem. Energy deficits combined with increased levels of physical activity would increase the absolute protein requirement. Most of the studies that found mean protein intakes below the MRDA were conducted in the cold and involved the RCW, which was designed to contain less protein in an effort to conserve body water. Protein intakes ranged from 12 percent of calories for men consuming the RCW in the New Hampshire study (Roberts et al., 1987) to 18 percent of calories for men in the Bolivia study (Edwards et al., 1991). The women in the

Suggested Citation:"8 An Overview of Dietary Intakes During Military Exercises." Institute of Medicine. 1995. Not Eating Enough: Overcoming Underconsumption of Military Operational Rations. Washington, DC: The National Academies Press. doi: 10.17226/5002.
×

altitude study in Bolivia consumed only 68 g of protein, but protein intakes still averaged 16 percent of calories (Edwards et al., 1991).

One reason why protein intakes are relatively high is that service members, whether in garrison or eating operational rations in the field, typically consume the entree. Entrees are the major protein contributors in military rations. Because of the disproportionately greater consumption of the high-protein entrees, mean protein intakes during the MRE studies were 16 to 17 percent of calories, even thought the MRE provided only 14 to 15 percent of calories as protein (see Tables 8-4, 8-5, and 8-6).

Micronutrients

Calcium is one of the micronutrients of concern. Figure 8-1 depicts mean calcium intakes of most of the MND study groups. The Recommended Dietary Allowance (RDA) of 1,200 mg was used for comparison because many of the study participants were 25 years of age or less (NRC, 1989). These data reveal the problem of promoting adequate calcium intake in the field. The three field-study populations that met the RDA for calcium received aseptically-packaged milk as part of their hot meal provision. None of the studies with women found a mean calcium intake meeting the RDA of 1,200 mg, although all but

FIGURE 8-1 Mean calcium intakes of male and female service members compared to the Recommended Dietary Allowance (RDA) (NRC, 1989) of 1,200 mg for individuals 19 to 24 years of age. Data were combined from several studies as listed in endnote 1.

Suggested Citation:"8 An Overview of Dietary Intakes During Military Exercises." Institute of Medicine. 1995. Not Eating Enough: Overcoming Underconsumption of Military Operational Rations. Washington, DC: The National Academies Press. doi: 10.17226/5002.
×

two studies met the MRDA for calcium of 800 mg2. These two studies included women in Bolivia and the recent study of women undergoing basic training at Fort Jackson.

Figure 8-2 charts the folate intakes of most of the MND study groups. Very few of the groups met the MRDA for folate of 400 µg (AR 40-25, 1985). If the 1989 reduced RDA values for folate were used for comparison, (men: 200 µg; women: 180 µg), four of seven field studies with men for which folate was analyzed would have found adequate intakes, and study means of three of the four studies with women would have met the criterion. Given that almost all female service members are of child-bearing age, the higher MRDA figure may be more appropriate. An argument often presented to counter the findings of low folate intakes is that there are too many missing values for folate in the ration data base. Data are thus also missing in the present analysis, but most of the ration items for which folate data are missing would be insignificant sources of this nutrient.

FIGURE 8-2 Mean folate intakes of male and female service members compared to the Military Recommended Dietary Allowance (MRDA) (AR 40-25, 1985) of 400 µg. Data for folate were not reported due to missing food composition data.

Data were combined from several studies as follows listed in endnote 2.

2  

The MRDAs (AR 40-25, 1985) are based on the earlier ninth edition of the RDAs (NRC, 1980), and are being revised.

Suggested Citation:"8 An Overview of Dietary Intakes During Military Exercises." Institute of Medicine. 1995. Not Eating Enough: Overcoming Underconsumption of Military Operational Rations. Washington, DC: The National Academies Press. doi: 10.17226/5002.
×
Food Waste

Another way to measure underconsumption of rations is to look at food waste. When energy intakes were compared to calories provided, energy intakes were consistently 1,000 to 2,000 kcal less than issue. Table 8-7 presents nutrient consumptions as a percentage of what was provided. Mean energy intakes ranged from 47 to 78 percent of the energy provided when the ration approximated energy requirements. Only in the study in which the Ration, Lightweight (RLW) was provided as a restricted ration did ration consumption approach 100 percent (Askew et al., 1987). MND study participants tended to consume more of the protein in the ration than they did energy or carbohydrate. Eleven of the 14 study groups listed in Table 8-7 consumed a greater percentage of the protein in the ration than they did of the energy provided. This finding illustrates the disproportionate consumption of ration components, with service members favoring the high-protein entrees. Despite a significant amount of food waste, soldiers tended to rate the amount of food provided as insufficient.

One reason nutrients are not consumed is that they are not taken to the field. When soldiers were allowed to take only the ration components they wanted to the field (based on two studies that were able to document this information), they took only 3,400 to 3,600 kcal, which was about 70 percent of the ration issued (Askew et al., 1987; Roberts et al., 1987). Of this, they consumed about 2,700 kcal. These two study groups were provided 4,023 kcal and 4,892 kcal, respectively. Space in the backpack is at a premium and therefore, soldiers will not carry what they know they will not eat or what is too heavy or too bulky. This fact was reemphasized by a study conducted by Natick Research, Development and Engineering Center at Fort Chaffee, Arkansas in 1985 (Siegal et al., 1985). One test group in the study was allowed to take to the field only what they ''normally would take." This "normal" group took a combination of ration components and commercial products. Unfortunately, the amount of food or ration items actually taken was not quantified; however, judging by nutrient intakes, the quantity taken was minimal. The normal group consumed a mean of only 1,028 kcal, 126 g of carbohydrate, and 41 g of protein over the 12 days of the study. They consumed 689 kcal and 855 kcal less, respectively, than the other two test groups who were intentionally provided calorically restricted rations.

Variety

Increasing the variety of tastes, textures, or colors increases food intakes (Rolls et al., 1981, 1982). This fact was exemplified by a study conducted in

Suggested Citation:"8 An Overview of Dietary Intakes During Military Exercises." Institute of Medicine. 1995. Not Eating Enough: Overcoming Underconsumption of Military Operational Rations. Washington, DC: The National Academies Press. doi: 10.17226/5002.
×

TABLE 8-7 Proportion of Nutrient Provision Consumed (in Percent)

Ration

Year

Location

Energy

Carbohydrate

Protein

Fat

Reference

RLW*

1986

Camp Ethan Allen, VT

98

100

94

97

Askew et al., 1987

2:RLW†

1988

MMWTC‡

76

86

77

67

Morgan et al., 1988

2:RLW + Suppl.§

1989

Mt. Rainier, WA

47

47

51

41

Jones et al., 1990

4:MRE III

1986

White Mountains, NH

56

55

57

55

Roberts et al., 1987

MRE VI

1986

Camp Ethan Allen, VT

69

64

74

74

Askew et al., 1987

4:MRE VIII

1988

MMWTC

62

57

69

67

Morgan et al., 1988

MRE VIII + Suppl.

1989

Alaska

78

76

70

79

Edwards et al., 1989

MRE VIII + Suppl.

1990

Alaska

59

~57

~59

~79

Edwards et al., 1990

MRE XII

1991

Ft. Chaffee, AR

55

50

65

58

Thomas et al., unpublished**

RCW

1986

White Mountains, NH

61

56

77

65

Roberts et al., 1987

RCW

1988

MMWTC

65

62

79

65

Morgan et al., 1988

RCW

1988

Alaska

57

51

65

64

Roberts et al., 1989

RCW

1990

Alaska

64

~64

~81

~68

Edwards et al., 1990

2:T & 1:MRE

1991

Alaska

51

44

60

57

King et al., 1992

*, Ration, Lightweight, a completely dehydrated, restricted calorie ration, provided approximately 1,976 kcal, 194 g of carbohydrate, 68 g of protein, and 103 g of fat; , Ration Lightweight provided 4,219 kcal, 400 g of carbohydrate, 142 g of protein, and 230 g of fat; , Marine Mountain Warfare Training Center, Pickel Meadows, Calif.; §, Ration, Lightweight plus supplement provided 5,200 kcal, 700 g of carbohydrate, 142 g of protein, and 230 g of fat; , macronutrient provision not quantified in report; estimated from current ration data; **, C. D. Thomas et al., U.S. Army Research Institute of Environmental Medicine, Natick, Mass., unpublished data; , Ration, Cold Weather.

Suggested Citation:"8 An Overview of Dietary Intakes During Military Exercises." Institute of Medicine. 1995. Not Eating Enough: Overcoming Underconsumption of Military Operational Rations. Washington, DC: The National Academies Press. doi: 10.17226/5002.
×

Alaska in 1989 (Edwards et al., 1989). When a supplement pack containing candy, jerky, and trail mix was added to the MRE, energy intakes were higher (3,533 Kcal) than when the same number of calories (4,565 kcal) was provided by simply providing more MREs (2,802 kcal) (Figure 8-3). Not only did the supplements contribute to energy intakes, but consumption of the MRE was greater as well.

In contrast, the next year when 4,604 kcal were provided by a similar supplement pack with the MRE, energy intakes were only 2,729 kcal (Edwards et al., 1990). However during this second year, physical activities of the test unit were much lower than those of the unit studied in 1989. Based on energy intake and body weight loss, assuming that the energy deficit incurred by body weight loss is 3,500 kcal per pound, energy expenditures were 4,603 kcal and 3,954 kcal for the MRE VIII + supplement groups in 1989 and 1990, respectively. But weight losses of the two supplemented groups were comparable, 1.7 percent and 1.6 percent for the 1989 and 1990 study groups, respectively. So, although the unit studied the second year did not require as many calories and, therefore, theoretically needed to eat less and could more easily meet their needs, the weight-loss data indicate that they experienced the

FIGURE 8-3 Effect of supplement pack with the Meal, Ready-to-Eat (MRE) on energy intakes during two cold-weather field studies. Figures in parentheses are the years of the respective studies. Three or 3 1/2 MREs (3 1/2:MRE) were provided as the ration. Data compiled from Edwards et al. (1989, 1990).

Suggested Citation:"8 An Overview of Dietary Intakes During Military Exercises." Institute of Medicine. 1995. Not Eating Enough: Overcoming Underconsumption of Military Operational Rations. Washington, DC: The National Academies Press. doi: 10.17226/5002.
×

same energy deficit. Therefore, whereas increasing the variety of ration components should be done to enhance dietary intakes, this should not be expected to prevent weight loss.

Energy Intakes Versus Energy Expenditures

The best way to assess energy deficit during field operations is to compare energy intakes to actual energy expenditures. MND has used the doubly labeled water method (Schoeller and van Santen, 1982) to measure energy expenditures in subsamples of study groups in six field studies. Table 8-8 presents the results of these studies.

Energy deficits ranged from 520 kcal/d, in a group that was moderately active in a temperate environment, to 2,199 kcal/d in a group conducting a difficult mountain operation under extreme winter conditions. Average energy deficit for the six studies was 1,552 kcal/d or 34 percent.

Table 8-8 Energy Intake as a Proportion of Energy Expenditure

Year

Environment and Location

Energy Expenditure (kcal)

Energy Intake (kcal)

Difference (kcal)

Proportion (%)

Reference

1986

Temperate, Vermont

3,480

2,960

520

85

Askew et al., 1987

1988

Cold, high altitude, California.

4,900

3,132

1,768

64

Morgan et al., 1988

1990

Cold, Alaska

180

3,060

2,120

59

Edwards et al., 1990

1991

Cold, Alaska

4,250

3,330

920

78

King et al., 1992

1990

Cold, high altitude, Washington

4,557

2,358

2,199

52

Jones et al., 1990

1990

Cold, high altitude, Bolivia

3,549

2,200

1,349

64

Edwards et al., 1990

. Marine Mountain Warfare Training Center, Pickel Meadows, Calif.

† This study was not included in the rest of this paper because of small sample size and short duration. Data from Hoyt et al. (1994).

Suggested Citation:"8 An Overview of Dietary Intakes During Military Exercises." Institute of Medicine. 1995. Not Eating Enough: Overcoming Underconsumption of Military Operational Rations. Washington, DC: The National Academies Press. doi: 10.17226/5002.
×

The doubly labeled water data confirm that a significant component of the weight losses observed during field operations is due to an energy deficit and cannot be solely attributed to a fluid deficit. Although partly explainable, the energy deficits and resulting acute weight losses are of concern. Significant weight loss is almost always accompanied by loss of lean body mass as well as fat. The greater the energy deficit and the leaner the individual, the greater is the relative contribution of lean tissues to the energy deficit (Forbes, 1987). Military weight control standards insure that most service members are relatively lean. An energy deficit in excess of 1,000 kcal/d in lean individuals could lead to detrimental losses of glycogen, body water, electrolytes, and body proteins.

CONTRIBUTING FACTORS

There is no single cause of ration underconsumption in the field, and there will be no simple solution. Most of the factors that MND has identified that contribute to underconsumption fall into one of four interrelated categories: the ration, training schedule, environment, and command emphasis.

The Ration

Provision of at least one hot meal per day enhances nutrient intake. It does not seem to matter whether the hot meal is a T or B Ration, but there is an even greater benefit if the hot meal is an A Ration meal. When hot meals are provided, the primary reasons soldiers give for not getting enough to eat is dislike of the ration, not receiving enough food to eat, and lack of variety or boredom with the food. Taste fatigue of sweets is common. Providing more food positively affects absolute nutrient intakes, although service members seem to consume a relatively smaller proportion of the ration provided. In other words, the enhanced intakes are at the expense of greater food waste. When soldiers must carry their own food, they have to juggle competing priorities for positions in the rucksack. Food and nutrition often lose out.

Training Schedule and Situation

When prepackaged rations are provided, the commonly cited reason for not getting enough to eat is insufficient time to prepare and eat the rations. On days when soldiers are moving their position, ration intakes are low, whereas on days that soldiers are stationary, energy intakes increase because they have

Suggested Citation:"8 An Overview of Dietary Intakes During Military Exercises." Institute of Medicine. 1995. Not Eating Enough: Overcoming Underconsumption of Military Operational Rations. Washington, DC: The National Academies Press. doi: 10.17226/5002.
×

more time and greater opportunity to heat and eat the rations. In the Fort Sill study (Rose and Carlson, 1986), it appears that intakes were high not just because A Rations were provided, but also because there were fairly regular, scheduled meal periods.

Environment

Environmental stress adds to the physical and emotional stress of field operations or combat. There are increased energy and water requirements in hot, cold, and high-altitude environments. Furthermore, these environments may induce anorexia and an inappropriate thirst response in some individuals. Dehydration itself results in anorexia. The availability of potable water directly affects water and ration intakes, especially if ration components require rehydration before eating.

Harsh environments may also directly affect the training schedule because all tasks are more difficult and take longer to accomplish. This further erodes the time available to prepare and eat rations. In the cold, the process of eating is more bothersome because it is difficult to rehydrate or heat a ration in the cold, to get water and keep it from freezing, and to open ration packages with gloved or cold, stiff hands.

Environment also affects the quality of foods. Foods that are hot in the kitchen tent may literally be ice cold by the time they reach the squad tent. In hot weather, foods may be served at temperatures inappropriate to the type of food, for example, aseptically packaged milk served at 95¹F (35¹C). Blowing dust or sand can quickly render a meal unsuitable for consumption. Food preferences are also altered at environmental extremes. In cold weather, soldiers prefer hot foods and cocoa, while in the heat, they prefer ice tea and Kool Aid. A high-fat diet may be tolerated in the cold, but it is not well tolerated at high altitude. Preference for fat has been expressed in the Arctic while a preference for carbohydrate has been recorded at high altitude (Ward et al., 1989).

Command Emphasis

Commanders and soldiers view the energy deficit as acceptable and unavoidable. The consequences of inadequate intakes of carbohydrate, protein, sodium, water, or other nutrients are not appreciated. Field feeding decisions are based more on personal preference and logistical considerations than on nutrition. R. M. Kark (1954, p. 193) found that, "Loss of military efficiency through inadequate nutrition is most often due to inadequate planning, catering

Suggested Citation:"8 An Overview of Dietary Intakes During Military Exercises." Institute of Medicine. 1995. Not Eating Enough: Overcoming Underconsumption of Military Operational Rations. Washington, DC: The National Academies Press. doi: 10.17226/5002.
×

or supply, and to inadequate training or indoctrination." Lack of command emphasis on the importance of ration consumption may be perceived by the troops as an indication that nutrition is not important.

CONCLUSIONS AND RECOMMENDATIONS

The available data clearly show consistent energy and carbohydrate deficits, whether based on comparisons with dietary allowances, nutrient provisions, or energy requirements. The carbohydrate deficit is of concern, as it is more detrimental to performance. Carbohydrate stores are finite and easily depleted, whereas fat stores are relatively unlimited. Although simple energy imbalances are well tolerated for short periods, further research is needed on the effects of frequent weight cycling at the levels reported here in healthy, nonobese populations.

Although short-term vitamin or mineral deficits are well tolerated, the nutritional consequences of frequent, repeated periods of inadequate intake may not be so benign. The reduction in military populations will result in an increase in the amount of time spent in the field by the remaining troops. This effect is already being felt by some units that are in the field 40 to 50 percent of the time (Personal communication, C. Thomas, Dietitian, 55th Medical Group, Fort Bragg, N.C., 1993). The low calcium and folate intakes by female service members are also of concern; these nutrients are also often low in the diets of military women when in garrison (Klicka et al., 1993; Kretsch et al., 1984, 1986; R.W. Rose et al., 1989).

Although weight losses in the field are not inevitable, they are certainly difficult to prevent because of the myriad of contributing factors, many of which are not under the control of the individual or the commander. The goal should not be to prevent weight loss, but to prevent unacceptable levels of weight loss. Some recommendations are:

  • Define what constitutes an unacceptable weight loss.

  • Require unit commanders to weigh their troops immediately before and after a field operation (similar to a coach weighing the team before and after practice). This would emphasize the importance of maintaining food and water intakes in the field.

  • Just as the military has been fairly successful with water discipline, they may need to consider developing some form of food discipline as well.

  • Greater emphasis should be placed on the promotion of optimal carbohydrate intakes.

Suggested Citation:"8 An Overview of Dietary Intakes During Military Exercises." Institute of Medicine. 1995. Not Eating Enough: Overcoming Underconsumption of Military Operational Rations. Washington, DC: The National Academies Press. doi: 10.17226/5002.
×
  • Efforts to increase the variety of ration components should target snack foods as well as entrees, since these "eat-on-the-go" foods provide most of the carbohydrates.

  • Just as there are 12 or more MRE entrees, there could be 12 or more different starches and snacks. Slight variations in taste, texture, form, or color could constitute the differences (e.g., various flavors of crackers).

  • The return of sweetened beverage bases to all ration menus should be investigated, as these were popular and effective sources of carbohydrate. Half of the MRE menus now contain artificially sweetened beverage-base powder.

ENDNOTES

1.  

Data on calcium intakes for Figure 8-1 were combined from the following studies: Garrison: Szeto et al. (1987, 1988, 1989) and C. D. Thomas et al. (U.S. Army Research Institute of Environmental Medicine, Natick, Mass., unpublished data); Academy: Baker-Fulco et al. (1990, 1994), Carlson et al. (1987), Klicka et al. (1993), Kretsch et al. (1986), and R. W. Rose et al. (1989); Field: Askew et al. (1987), Edwards et al. (1990, 1991), King et al. (1992), Morgan et al. (1988), Roberts et al. (1989), Rose and Carlson (1986), M.S. Rose et al. (1989), and C. D. Thomas et al. (U.S. Army Research Institute of Environmental Medicine, Natick, Mass., unpublished data); Combined Women: Edwards et al. (1991), King et al. (1994), Klicka et al. (1993), Kretsch et al. (1986), M.S. Rose et al. (1989), R.W. Rose et al. (1989), and Szeto et al. (1987).

2.  

Data on folate intakes for Figure 8-2 were combined from the following studies: Garrison: Szeto et al. (1987, 1988, 1989) and C. D. Thomas et al. (U.S. Army Research Institute of Environmental Medicine, Natick, Mass., unpublished data); Academy: Baker-Fulco et al. (1992, 1994), Carlson et al. (1987), Klicka et al. (1993), and Kretsch et al. (1986); Field: Edwards et al. (1990, 1991), Morgan et al. (1988), Roberts et al. (1989), Rose and Carlson (1986), M.S. Rose et al. (1989), and C. D. Thomas et al. (U.S. Army Research Institute of Environmental Medicine, Natick, Mass., unpublished data); Combined Women: Edwards et al. (1991), King et al. (1994), Klicka et al. (1993), Kretsch et al. (1986), M.S. Rose et al. (1989), and Szeto et al. (1987).

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Suggested Citation:"8 An Overview of Dietary Intakes During Military Exercises." Institute of Medicine. 1995. Not Eating Enough: Overcoming Underconsumption of Military Operational Rations. Washington, DC: The National Academies Press. doi: 10.17226/5002.
×

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Suggested Citation:"8 An Overview of Dietary Intakes During Military Exercises." Institute of Medicine. 1995. Not Eating Enough: Overcoming Underconsumption of Military Operational Rations. Washington, DC: The National Academies Press. doi: 10.17226/5002.
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Schoeller, D.A., and E. van Santen 1982. Measurement of energy expenditure in humans by doubly labeled water method. J. Appl. Physiol. 53:955–959.

Suggested Citation:"8 An Overview of Dietary Intakes During Military Exercises." Institute of Medicine. 1995. Not Eating Enough: Overcoming Underconsumption of Military Operational Rations. Washington, DC: The National Academies Press. doi: 10.17226/5002.
×

Siegal, S.F, P.M. Poole, E.W. Askew, M.A. Kinney, C. Shaw, J. Aylward, and S. Hunter 1985. Twelve-day field test of Ration, Lightweight, 30-day at Fort Chaffee, Arkansas. Technical Report TR-87/032. Natick, Mass.: U.S. Army Natick Research and Development Center.

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Suggested Citation:"8 An Overview of Dietary Intakes During Military Exercises." Institute of Medicine. 1995. Not Eating Enough: Overcoming Underconsumption of Military Operational Rations. Washington, DC: The National Academies Press. doi: 10.17226/5002.
×

DISCUSSION

ROBERT NESHEIM: Thank you very much. We have time for a question.

RICHARD JANSEN: Are there any systematic weight data coming back from Operation Desert Shield and/or Desert Storm on the weight of the troops when they were deployed?

CAROL BAKER-FULCO: No, that unfortunately was not obtained. What I noticed, when soldiers anecdotally tell you how much weight they lost, is a grossly inflated amount in any situation.

PRISCILLA DOLLOFF-CRANE: We had a unit come back to Fort Lee from Somalia. Not Desert Shield and Desert Storm but Somalia. They were on a 2.5-m deployment from January to the middle of March 1993. Coincidentally, their commander had them perform PT (physical training) tests shortly before their deployment, and she had good starting weights for them. When she brought them back, we asked her to weigh them again. The weight ranges for fit troops were anywhere from a 10-to 35-lb drop in that 2.5-m period. They were not overweight to begin with, and there was no command pressure to lose weight. The commander did notice a lot of performance deficiencies during that time. There was not a scientific analysis, but the data are there to support the finding.

GILBERT LEVEILLE: Did they have a problem with diarrhea at that point?

PRISCILLA DOLLOFF-CRANE: No, not so much diarrhea. It was the environmental and psychological stress factors that were pronounced in the environment they were working in. Of course, nobody is sensitized to exactly what we said in terms of the command emphasis and the leadership issues involved. That is, it is accepted that you are going to lose some weight. The thing is that we are traditionally in 2-wk exercises so this attitude we have all developed is that weight loss is okay. Over a short period of time, we do not have compensatory measures in place for that.

HOWARD SCHUTZ: There are two points that are going to recur when we come up with questions. First, when we focus on carbohydrate, is the level required for maintenance of glycogenic performance supported by data? Do we really have data to support a relationship between performance and intake?

CAROL BAKER-FULCO: Not in soldiers, no.

Suggested Citation:"8 An Overview of Dietary Intakes During Military Exercises." Institute of Medicine. 1995. Not Eating Enough: Overcoming Underconsumption of Military Operational Rations. Washington, DC: The National Academies Press. doi: 10.17226/5002.
×

EDWARD HIRSCH: And the second point related to that. When we talk about things like folate, I was intrigued by your comment that they eat the entree and don't eat the other stuff. Have we really looked at adding whatever nutrients we are going to add to the entree rather than to the peripheral items?

(NO ANSWER HERE TO QUESTION)

HOWARD SCHUTZ: Was there any relationship between any of the underconsumption and any of the changes in the MRE that the previous speakers discussed? Because apparently there has been improvement over time. Have you noticed any reflection of that in the underconsumption data?

CAROL BAKER-FULCO: Almost during any study where we are comparing a new to an old ration, the new ration will fare much better, at least the first year we study it. If that becomes the control the next year, that is the poor ration. There is a big novelty factor.

STEPHEN PHINNEY: Have there been any attempts to add carbohydrate supplements to water to capitalize on your emphasis on the water discipline? If you get the caloric density of the beverage to 25 kcal/cc, 2 liters of water will give you 1,000 kcal of carbohydrate per day.

CAROL BAKER-FULCO: Not in conjunction with water discipline, but almost as an ergogenic aid, as a supplement. Special operations forces would use this more as a supplement.

ROBERT NESHEIM: In the sports world, it has become a component of success.

CAROL BAKER-FULCO: Yes. A liquid supplement seems to be much better.

ROBERT NESHEIM: I think we have to be a little careful in looking at what might be a carbohydrate requirement, for example, in terms of maintaining muscle glycogen because a soldier is not a marathon runner. The level of activity for a soldier is not as high for a prolonged period of time. Consequently, even on a lower carbohydrate intake, there is an opportunity for regeneration of muscle glycogen if they are eating. So I think we cannot make those direct translations, and we have to be very careful.

DAVID SCHNAKENBERG: I think it is not a question of whether you can maintain or restore muscle glycogen by adding carbohydrate if you have not fixed the caloric energy deficit. I mean, if you put in even 400, 500, or 600 g

Suggested Citation:"8 An Overview of Dietary Intakes During Military Exercises." Institute of Medicine. 1995. Not Eating Enough: Overcoming Underconsumption of Military Operational Rations. Washington, DC: The National Academies Press. doi: 10.17226/5002.
×

of carbohydrate, if you still have an energy deficit, you are going to have difficulty in restoring your energy.

EDWARD HIRSCH: I just wanted to ask Carol quickly about women and the number of women in your samples. Are they substantial enough?

CAROL BAKER-FULCO: I am not sure if I have the actual N values of the women. I can look it up and answer, but I cannot remember the N values now. I have been pulling this data from reports, and they are all jumbled up in my mind right now.

EDWARD HIRSCH: Because the numbers we are starting to see are five or six or seven in a group in a field study and never quite enough to know what is going on.

Suggested Citation:"8 An Overview of Dietary Intakes During Military Exercises." Institute of Medicine. 1995. Not Eating Enough: Overcoming Underconsumption of Military Operational Rations. Washington, DC: The National Academies Press. doi: 10.17226/5002.
×
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Eating enough food to meet nutritional needs and maintain good health and good performance in all aspects of life--both at home and on the job--is important for all of us throughout our lives. For military personnel, however, this presents a special challenge. Although soldiers typically have a number of options for eating when stationed on a base, in the field during missions their meals come in the form of operational rations. Unfortunately, military personnel in training and field operations often do not eat their rations in the amounts needed to ensure that they meet their energy and nutrient requirements and consequently lose weight and potentially risk loss of effectiveness both in physical and cognitive performance. This book contains 20 chapters by military and nonmilitary scientists from such fields as food science, food marketing and engineering, nutrition, physiology, psychology, and various medical specialties. Although described within a context of military tasks, the committee's conclusions and recommendations have wide-reaching implications for people who find that job-related stress changes their eating habits.

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