Chapter 24- Estimating Chapter 24- Estimating Energy RequirementsEnergy Requirements

Jacalyn J. Robert-McComb, Jacalyn J. Robert-McComb, PhD, FACSMPhD, FACSM

Learning ObjectivesLearning Objectives

Following this presentation, you should Following this presentation, you should have an understanding of:have an understanding of:

the components of energy expenditure;the components of energy expenditure; methods of measuring energy methods of measuring energy

expenditure;expenditure; average dietary reference intake values average dietary reference intake values

of energy for active individuals; andof energy for active individuals; and estimated energy expenditure estimated energy expenditure

prediction equations.prediction equations.

Introduction to the Concept Introduction to the Concept of Energyof Energy

Energy is defined as “the capacity to Energy is defined as “the capacity to do work”. Energy is expended by the do work”. Energy is expended by the human body in the form of resting human body in the form of resting energy expenditure energy expenditure (REE),(REE), the the thermic effect of food thermic effect of food (TEF),(TEF), and and energy expended in physical activity energy expended in physical activity also referred to as also referred to as EEPA EEPA (Fray & (Fray & Johnson, 2004; Institute of Medicine (U.S.), Johnson, 2004; Institute of Medicine (U.S.), Standing Committee on the Scientific Evaluation Standing Committee on the Scientific Evaluation of Dietary Reference Intakes, 2002).of Dietary Reference Intakes, 2002).

Energy expended

in physical activity

(EEPA)~15% - 30%

Thermic effect of

feeding (TEF) ~ 10%

 

Resting energy

expenditure (REE)

~60% - 75%

  

 

 

Components of Energy

Resting Energy Resting Energy ExpenditureExpenditure

Resting energy expenditure (REE) is the Resting energy expenditure (REE) is the energy expended in the activities energy expended in the activities necessary to sustain normal body necessary to sustain normal body functions and homeostasis. This energy functions and homeostasis. This energy encompasses respiration, circulation, encompasses respiration, circulation, the synthesis of organic compounds, the the synthesis of organic compounds, the pumping of ions across membranes, the pumping of ions across membranes, the energy required by the central nervous energy required by the central nervous system, and the maintenance of body system, and the maintenance of body temperature. temperature.

Factors that cause the Factors that cause the REE to vary among REE to vary among

individuals individuals Body Size and Weight (Body Body Size and Weight (Body

Surface Area), Surface Area), Body Composition, Body Composition, Age, Age, Sex, and Sex, and Hormonal status Hormonal status

REEREE

The main determinant of REE is fat-The main determinant of REE is fat-free mass (FFM) or lean body mass free mass (FFM) or lean body mass (LBM). (LBM).

Because of their greater FFM, Because of their greater FFM, athletes or individuals who are athletes or individuals who are extremely fit have approximately a extremely fit have approximately a 5% higher basal metabolic rate 5% higher basal metabolic rate (BMR) than nonathletic individuals. (BMR) than nonathletic individuals.

Methods of Measuring Methods of Measuring Energy ExpenditureEnergy Expenditure

The Doubly Labeled Water Technique The Doubly Labeled Water Technique (DLW)(DLW)

Direct Calorimetry Direct Calorimetry Indirect CalorimetryIndirect Calorimetry Surveys/ Questionnaires Surveys/ Questionnaires

The Seven Day Recall Physical Activity The Seven Day Recall Physical Activity Yale Activity Survey Yale Activity Survey

Estimated Energy Expenditure Estimated Energy Expenditure Prediction Equations Prediction Equations

The Doubly Labeled Water The Doubly Labeled Water Technique (DLW)Technique (DLW)

This method uses two stable isotopes of water This method uses two stable isotopes of water (deuterium [2H2O] and oxygen -18 [H218O]); (deuterium [2H2O] and oxygen -18 [H218O]); the difference in the turnover rates of the two the difference in the turnover rates of the two isotopes measures the carbon dioxide isotopes measures the carbon dioxide production rate, from which total energy production rate, from which total energy expenditure can be calculated. expenditure can be calculated.

The DLW technique has many advantages; The DLW technique has many advantages; however, the expense of the technique makes however, the expense of the technique makes this technique impractical for daily use by this technique impractical for daily use by clinicians. clinicians.

The primary advantage of this technique is its The primary advantage of this technique is its accuracy (2-8% precision) and that it provides accuracy (2-8% precision) and that it provides a measure of energy expenditure that a measure of energy expenditure that incorporates all the components of TEE, REE, incorporates all the components of TEE, REE, TEF, and EEPA (1,9). TEF, and EEPA (1,9).

Direct CalorimetryDirect Calorimetry

This is a method for measuring the This is a method for measuring the amount of energy expended by amount of energy expended by monitoring the rate at which a person monitoring the rate at which a person loses heat from the body using a loses heat from the body using a structure called a whole-room structure called a whole-room calorimeter. calorimeter.

Direct calorimetry provides a measure of Direct calorimetry provides a measure of energy expended in the form of heat but energy expended in the form of heat but does not provide information on the type does not provide information on the type of fuel being oxidized. of fuel being oxidized.

Indirect Indirect Calorimetry Calorimetry

This is a method of estimating energy This is a method of estimating energy production by measuring oxygen production by measuring oxygen consumption and carbon dioxide consumption and carbon dioxide utilizing a respirator gas-exchange utilizing a respirator gas-exchange canopy or ventilation hood. canopy or ventilation hood.

Data are obtained from indirect Data are obtained from indirect calorimetry that permits calculation of calorimetry that permits calculation of the respiratory quotient (RQ= moles the respiratory quotient (RQ= moles CO2 expired/moles O2 consumed). CO2 expired/moles O2 consumed).

Depending on the RQ value, energy Depending on the RQ value, energy per liter of oxygen will be converted per liter of oxygen will be converted

Estimated Energy Estimated Energy Expenditure Prediction Expenditure Prediction

EquationsEquations The National Academy of Sciences, Institute of The National Academy of Sciences, Institute of

Medicine (IOM), and Food and Nutrition Board in Medicine (IOM), and Food and Nutrition Board in partnership with Health Canada, developed new partnership with Health Canada, developed new prediction equations to estimate energy requirements prediction equations to estimate energy requirements (EER) for people according to their life-stage group (EER) for people according to their life-stage group

The EER incorporates age, weight, height, gender, The EER incorporates age, weight, height, gender, and level of physical activity for individuals in various and level of physical activity for individuals in various life-stages. life-stages.

These equations should only be used as a guide to These equations should only be used as a guide to promote optimal nutritional status; the individual promote optimal nutritional status; the individual should be monitored closely to adjust caloric intake should be monitored closely to adjust caloric intake based on target goals and changes in body mass. based on target goals and changes in body mass.

As in all prediction equation, standard errors are As in all prediction equation, standard errors are inherent .inherent .

Sample Equation Sample Equation EER for Women 19 Years and Older (BMI 18.5-25 EER for Women 19 Years and Older (BMI 18.5-25

kg/m2)kg/m2) EER = TEEEER = TEE EER = 354 – (6.91 X Age [yr]) + PA X (9.36 X Weight EER = 354 – (6.91 X Age [yr]) + PA X (9.36 X Weight

[kg] + 726 X Height [m])[kg] + 726 X Height [m]) WhereWhere PA = Physical activity coefficient:PA = Physical activity coefficient: PA = 1.0 if PAL is estimated to be PA = 1.0 if PAL is estimated to be >> 1.0 < 1.4 1.0 < 1.4

(Sedentary)(Sedentary) PA = 1.12 if PAL is estimated to be PA = 1.12 if PAL is estimated to be >> 1.4 < 1.6 (Low 1.4 < 1.6 (Low

Active)Active) PA = 1.27 if PAL is estimated to be PA = 1.27 if PAL is estimated to be >> 1.6 < 1.9 (Active) 1.6 < 1.9 (Active) PA = 1.45 if PAL is estimated to be PA = 1.45 if PAL is estimated to be >> 1.9 < 2.5 (Very 1.9 < 2.5 (Very

Active)Active)

Average dietary reference Average dietary reference intake values of energy for intake values of energy for active females individuals active females individuals

(non-pregnant)(non-pregnant) 0-6 mo0-6 mo 520(3mo)520(3mo) 7-12 mo7-12 mo 676(9mo)676(9mo) 1-2 yr1-2 yr 992(24mo)992(24mo) 3-5 yr3-5 yr 1642(6yr)1642(6yr) 9-13 yr 9-13 yr 2071(11yr)2071(11yr) 14-18yr14-18yr 2368(16yr)2368(16yr) >18 yr>18 yr 2403‡(19yr)2403‡(19yr) ‡‡Subtract 10kcal/day for men and 7 Subtract 10kcal/day for men and 7

kcal/day for women for each year of age kcal/day for women for each year of age above 19 year. above 19 year.

SummarySummary

A clinical decision of whether an accurate A clinical decision of whether an accurate metabolic rate by measurement is required to metabolic rate by measurement is required to provide nutritional care and counseling should provide nutritional care and counseling should be made on a case by case basis. If the target be made on a case by case basis. If the target goals are not being met, the client should be goals are not being met, the client should be monitored closely utilizing any dietary intake monitored closely utilizing any dietary intake records, energy expenditure logs, and records, energy expenditure logs, and physiological measurements of body mass and physiological measurements of body mass and or weight change. Indirect calorimetry may be or weight change. Indirect calorimetry may be an important tool when, in the judgment of the an important tool when, in the judgment of the clinician, the predictive methods fail an clinician, the predictive methods fail an individual in a clinically relevant way individual in a clinically relevant way (Frankenfield, Roth-Yousey, Compher, et al., (Frankenfield, Roth-Yousey, Compher, et al., 2005 ). 2005 ).