Not Eating Enough Overcoming Underconsumption of Military Operational Rations (1995) / Chapter Skim
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15 Impact of Underconsumption on Cognitive Performance
15 Impact of Underconsumption on Cognitive Performance
Pages 285-302
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From page 285... ...
The outcome of military nutrition research must be rations that are readily consumed in quantities sufficient to fuel maximum intellectual and physical performance. Thus, the question of whether underconsumption is reliably associated with measurable degradation in intellectual behavior is of considerable concern to developers of military rations.
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From page 286... ...
However, the vast majority of the studies were not designed to study the relationship of underconsumption to cognitive performance, per se, or the ability of military rations to sustain cognitive performance under stress. Underconsumption For the purposes of this review, underconsumption was operationally defined as a loss of gross body weight due to restrained eating, loss of appetite, or exertion.
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From page 287... ...
but not prevent weight loss. Military rations are calorie dense and vitamin fortified to ensure that they will be nutritionally adequate even when consumed in small quantities (Askew et al.?
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From page 288... ...
The engineering of military field rations contributes to underconsumption, no doubt, but it is likely that eating cold rations. eating during short breaks eating bY yourself, performing O demanding physical exercise, and performing challenging intellectual tasks contribute far more.
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From page 289... ...
They shared the same field setting, but both ate field rations, both underconsumed, and both lost weight. Thus, it was impossible to determine whether underconsumption, the field setting, or some interaction of the two influenced performance on cognitive tests.
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From page 290... ...
When the purpose of a study is to determine whether cognitive performance is grossly degraded by extended subsistence on a specific ration, the variance in extraneous variables is largely irrelevant. However, when the purpose of the experiment is to determine the degree to which a specific level of consumption influences cognitive performance, this variance reduces the ability to characterize the effect precisely.
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From page 291... ...
, Consideration of Individual Differences The range of weight change was quite large in many of the studies where there was an average weight loss (Askew et al., 1987; Hirsch et al., 1985; King et al., 1992; Popper et al., 1987; Thomas et al., 1995~. That is, there were soldiers who gained weight, while the majority of their peers lost weight.
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From page 292... ...
However, this begs the issue, since momentary inattentiveness or confusion can have fatal consequences in military field settings. Influence of Underconsumption on Cognitive Performance The literature on simple underconsumption of military rations is astonishingly consistent.
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From page 293... ...
suggest that underconsumption combined with other stressors significantly degrades cognitive performance. The training of special operations forces combines food deprivation with several stressors, including exercise, sleep deprivation, danger, and personal evaluation (Hudgens et al., 1992; Marriott, 1993; Moore et al., 1992; Opstad et al., 1978; Pleban et al., 1990; Rognum et al., 1986; Shippee et al., 1994~.
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From page 294... ...
Their estimates have been confirmed over the years in a variety of settings, including military field settings. Figure 15-1 illustrates their predictions concerning weight loss over a 60-d period.
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From page 296... ...
296 ~1 C~ CO ~ 1 UD o o o ~c'~ ~1 _H, // 1 1 1 UD o UD o a, ~co O ~ _ ._ C ~ C~ ~ m o U)
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From page 298... ...
A series of carefully designed doseresponse field studies need to be conducted for the sole purpose of defining the increase in cognitive performance that can be derived from a specific level of consumption. In summary, the following conclusions can be drawn from military nutrition field studies: · Weight losses of 6 percent or less over a period of 10 to 45 days produce no meaningful degradation in cognitive performance.
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From page 299... ...
Engell, and C.P. Shaw 1987 Nutritional status and physical and mental performance of special operations soldiers consuming the Ration, Lightweight or the Meal, Ready-to-Eat Military Field Ration during a 30-day field training exercise.
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From page 300... ...
Tulley 1992 Nutrition and hydration status of soldiers consuming the 18-man Arctic Tray Pack ration module with either the Meal, Ready-to-Eat or the Long Life Ration Packet during a cold weather field training exercise. Technical Report T4-92.
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From page 301... ...
Engell 1987 Nutritional and hydration status of special forces soldiers consuming the Ration, Cold Weather or the Meal? Ready-to-Eat ration during a 10-day cold weather field training exercise.
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From page 302... ...
The cognitive tests used in these studies ran the gamut from batteries ~=A r~;~^lP tP~t~ likP th~ r~mmoniv found on clinical neuropsycho logical tests to perforrrAance tests which lasted for hours and involved complicated decision-making tasks. In every case, they failed to show any effects of underconsumption when body weight losses were less than 6 ~UI1A~JKJ~11 ~J1 O1111V]
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