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ments might be made for body size, energy intake, or physiological status. However, such adjustments are usually not necessary since the DRIs are assumed to apply to all healthy individuals in the specified life stage and gender group.

Are there situations when adjustments to the Estimated Average Requirement (EAR), and thus the RDA, should be made for certain individuals to ensure that they are at little or no risk of nutrient inadequacy?

In most cases, adjustments are not likely to be required because the EAR already accounts for normal individual variability. However, adjustments may be warranted for individuals who have unusually high or low body weight, experience physiological changes at unusual ages, experience unusual physiological changes, or have unusually high energy requirements. These situations are discussed below.

Body Weight

When nutrient recommendations are established in relation to body weight, the weight of a reference individual is often used to derive DRIs. (See Appendix A for reference weights used in developing the DRIs.) For example, the RDA for protein has traditionally been related to body weight and in the 10th edition of the RDAs (NRC, 1989) the RDA for protein was set at 0.8 g of protein per kg body weight. Summary tables list RDAs of 63 and 50 g/day of protein, respectively, for reference adult men and women weighing 79 and 63 kg (NRC, 1989). Recommendations for individuals above or below these reference weights would be modified accordingly. For example, the RDA for individuals weighing 45 and 100 kg would be 36 and 80 g/day of protein, respectively. When this adjustment is made the individuals are assumed to have relatively normal body composition because protein requirements are related more strongly to lean body mass than to adipose tissue mass. Thus, a protein intake of 160 g/day would not be recommended for an obese individual weighing 200 kg. None of the DRIs established at the time this report went to press have been expressed in relation to body weight.



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