Chapter 18

Dietary Guidelines for Americans

A resource produced by the U.S. Department of Health & Human Services (HHS) and the United States Department of Agriculture (USDA) that provides guidelines and key recommendations for healthy diets that may help prevent diet-related chronic conditions.

The Food and Nutrition Board of the Institute of Medicine

An entity within the National Academies of Sciences that establishes principles and guidelines of adequate dietary intake among other tasks.

Dietary Reference Intakes (DRIs)

The recommended intake of various nutrients as determined by the Food and Nutrition Board of the Institute of Medicine – the DRIs include recommendations like the Recommended Dietary Allowance (RDA) and Acceptable Macronutrient Distribution Range (AMDR)

Acceptable Macronutrient Distribution Range (AMDR)

A range of intakes for carbohydrates, protein, and fats set by the Food and Nutrition Board of the National Academy of Medicine recommended to meet the nutritional needs of most individuals and reduce risk of chronic disease.

45-65% carbohydrates

25-35% fat

15-35% protein.

Recommended Dietary
Allowance (RDA)

Amount of nutrient needed to meet the needs of almost all individuals in an age–sex group.

Adequate Intake (AI)

The recommended average daily intake level based on observed or experimentally determined estimates of nutrient intake by groups of apparently healthy people that are assumed to be adequate – the AI is used when an RDA cannot be determined.

Tolerable Upper Intake Level
(UL)

The highest level of daily nutrient intake that is likely to pose no risk of adverse health effects to almost all individuals in the general population – as intake increases above the UL, the risk of adverse effects increases.

Estimated Average
Requirement (EAR)

A nutrient intake value that is estimated to meet the requirement of half the healthy individuals in a group.

Resting Metabolic Rate (RMR)

The amount of energy (i.e., number of calories) an individual uses at rest in order to sustain basic processes in the body – this value is often considered for a 24-hour period.

Adiposity

A condition of being severely overweight or obese.

Dietary Assessment

Analyzing a client’s food and beverage intake in order to determine their intake of calories and specific nutrients – specific forms of dietary assessment include 24-hour recalls, usual intake, diet records, and food frequency questionnaires.

Usual intake

The average daily intake of food or nutrients clients consumer over a long period of time.

Body composition

The makeup of an individual’s body– major components of interest include fat mass and fat-free mass (i.e., water, bone, protein, etc.).

Body Mass Index (BMI)

An individual’s weight divided by their height squared, typically shown in units of kilograms/meters².

2-Compartment Model

Any method of body-composition assessment that divides the body into two major parts – typically, these parts are fat mass and fat-free mass. Most common methods of body-composition assessment use a 2-compartment model.

3-Compartment Model

A method of body composition assessment that divides the body into three major parts – typically, these parts are fat mass, water, and everything else (i.e., the residual).

4-Compartment Model

A method of body composition assessment that divides the body into four major parts – typically, these parts are fat mass, water, bone, and everything else (i.e., the residual). These models are viewed as a gold-standard method of body-composition assessment.

To build this model, measurements of body weight, body volume, water, and bone content are needed. Body volume can be obtained by underwater weighing or air displacement plethysmography (ADP); water can be estimated by bioelectrical impedance analysis (BIA) and bone can be estimated using dual-energy X-ray absorptiometry (DXA)

Bioelectrical Impedance Analysis (BIA)

A technology that estimates body composition based on the fluid content, it produces a 2-compartment model to split the body into fat mass and fat-free mass.

It determines how easily small electrical currents travel through the body, and predict the amount of lean tissue (higher water content and easier flow of electricity) and fat tissue (lower water content and more resistance to electrical currents).

Skinfold Method

A body composition estimation method that is based on measuring the thickness of the fat layer under the skin – using calipers, the skin and fat are pinched at certain locations on the body to determine their thickness. These measurements are placed into a series of equations, which provide an estimate of body fat percentage using 2-compartment model.

the experience and skill of the health professional performing the assessments can greatly impact the accuracy of body-composition estimates.

Body Density

The estimated thickness of fat under the skin at specific locations when entered into an equation.

Ultra sound

Uses high-frequency sound waves emitted by a probe to visualize different parts of the body. It can determine the size or quality of a muscle as well as the thickness of the fat layer under the skin.
It can be performed at the same sites as a skinfold assessment and prediction equations can be used to estimate the overall body composition using a 2-compartment model (i.e. a more advanced version of skinfold calipers)

Circumference Measurements

Measurements of the circumferences of different body parts – these measurements provide some basic indication about the distribution of fat in the body, although they cannot actually distinguish between muscle and fat.

Underwater Weighing (Hydrodensitometry) or hydrostatic weighing

A body composition assessment method that involves the estimation of the 3-dimensional volume of the body through measurement of an individual’s body weight while they are completely submerged under water. this method estimates body composition in 2-compartment

Air Displacement Plethysmography (ADP)

A 2-compartment model body composition assessment method that involves the estimation of the 3-dimensional volume of the body through measurement of an individual’s displacement of air while they sit in a sealed chamber.

Dual-Energy X-Ray Absorptiometry

A 3-compartment model body composition assessment method that measures whole-body and regional (arms, legs, and trunk) body composition using low-energy X-rays.

This method is considered accurate but there can be error in an individual person’s results, which may be partially due to the amount of water in their body. Also this method is considered costly.

Infrared 3-Dimensional Scanning

A body composition assessment method that involves the estimation of the 3-dimensional volume of the body using infrared sensors.

Computed Tomography (CT)

Imaging procedure to create scans and pictures of inside the body.

Magnetic Resonance Imaging (MRI)

A medical imaging process that measures the reaction of tissue nuclei to magnetic fields to produce images of inside the body.

Hydrometry

The process of monitoring water within the body to determine body composition.

Near-Infrared Interactance (NIR)

A technique using a specialized probe against the body, emitting infrared light to estimate body composition of an individual.