Major new approaches and findings in this report include the following:

• The establishment of Estimated Energy Requirements (EER) at four levels of energy expenditure (Chapter 5).

• Recommendations for levels of physical activity associated with a normal body mass index range (Chapter 12).

• The establishment of RDAs for dietary carbohydrate (Chapter 6) and protein (Chapter 10).

• The development of the definitions Dietary Fiber, Functional Fiber, and Total Fiber (Chapter 7).

• The establishment of Adequate Intakes (AI) for Total Fiber (Chapter 7).

• The establishment of AIs for linoleic and α-linolenic acids (Chapter 8).

• Acceptable Macronutrient Distribution Ranges as a percent of energy intake for fat, carbohydrate, linoleic and α-linolenic acids, and protein (Chapter 11).

• Research recommendations for information needed to advance the understanding of human energy and macronutrient requirements and the adverse effects associated with intake of higher amounts (Chapter 14).

The scientific data used to develop Dietary Reference Intakes (DRIs) have come from observational and experimental studies. Studies published in peer-reviewed journals were the principal source of data. Life stage and gender were considered to the extent possible, but the data did not provide a basis for proposing different requirements for men, for pregnant and nonlactating women, and for nonpregnant and nonlactating women in different age groups for many of the macronutrients. Three of the categories of reference the values—the Estimated Average Requirement (EAR), Recommended Dietary Allowance (RDA), and Estimated Energy Requirement (EER)—are defined by specific criteria of nutrient adequacy; the third, the Tolerable Upper Intake Level (UL), is defined by a specific endpoint of adverse effect, when one is available (see Box S-1). In all cases, data were examined closely to determine whether a functional endpoint could be used as a criterion of adequacy. The quality of studies was examined by considering study design; methods used for measuring intake and indicators of adequacy; and biases, interactions, and confounding factors.

Although the reference values are based on data, the data were often scanty or drawn from studies that had limitations in addressing the various questions that confronted the panel. Therefore, many of the questions raised about the requirements for, and recommended intakes of, these macronutrients cannot be answered fully because of inadequacies in the present database. Apart from studies of overt deficiency diseases, there is a