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for sweat losses of nitrogen by diminished losses in the urine. Consolazio and Shapiro (1964) found that protein intakes of men exercising in a hot climate exceeded the then National Research Council (NRC) recommended allowances of 100 grams per day. They felt that the increased protein intake in the heat was not due to an innate desire for protein but to the relatively greater caloric intake that the men were consuming. Paul (1989) has suggested that because protein and amino acids contribute 5 to 15 percent of the energy for prolonged exercise, with the higher value perhaps associated with glycogen depletion, adequate protein intake is important when exercising in the heat. In Chapter 6, Buskirk concludes nevertheless, that there appears to be no evidence that protein intakes in excess of 1 to 1.5 grams per kilogram (kg) of body weight offer any advantage to the mature military person. Indeed, higher protein intakes may be a disadvantage, given the obligatory urine volume required to excrete the products of protein breakdown. The generous protein level of the MRDAs would suggest that somewhat lower levels might reduce body heat production while maintaining nutritional adequacy under conditions of high ambient temperatures. It should also be kept in mind that the matter of the relative proportions of protein, carbohydrate, and fat in hot environments is not yet entirely resolved.

Energy

Caloric requirements of troops are largely determined by the physical activities in which troops are engaged. The higher caloric intakes recommended for cold environments are largely due to the need to maintain thermal balance. It is interesting that studies of troops who operated in cold, moderate, and hot environments doing moderate work had essentially the same caloric requirements when calculated on the basis of body weight plus clothing and equipment being manually transported. In addition, a study that examined the performance of well-fed troops who were actively exercising in a hot environment with a group who experienced moderate energy restriction over a 12-day period found no difference in task performance between the groups, with both groups exhibiting weight loss (Crowdy et al., 1982). Buskirk (Chapter 6) concludes that for troops working in a hot environment, the submaximal exercise they perform has a far greater impact on their physiological functioning than if they performed the same tasks in a more comfortable environment. He also concludes that acclimatization plays a valuable role in physiological adaptation but that the process has only a minor part in modifying energy turnover and caloric requirements.

A major factor in meeting macronutrient requirements is the tendency for appetites to be adversely affected when unacclimatized personnel are suddenly exposed to a hot environment. Therefore, careful attention should



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