Module 3 Measurement of energy expenditure PDF

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Module 3: Measurement of energy expenditure This module relates to subject intended learning outcome 1: Use the basic principles of energy balance to determine an individual’s energy balance status. Related reading: Chapter 8 – energy balance and body composition and Appendix F – physical activity and energy requirements This module is designed to develop your understanding of energy, how energy is expended, and how we can measure (or estimate) energy expenditure. You will have the opportunity to estimate your own energy expenditure in Assessment Task 1. Estimating food energy intake: Duplicate food sample : burned in bomb calorimeter Record of weights of all foods eaten 24 hour recall diet history (usual weekly intake) food frequency questionnaire) Energy You will recall from Module 1 that our bodies require energy to maintain homeostasis and for all of our daily activities. Our bodies derive energy from the carbohydrate, protein and fat in our food. Alcohol, while not considered to be a nutrient, also contributes 29 kJ/g of energy. The energy density of foods (measured in kJ/g) depends on their nutrient composition. Foods that are higher in fat will be more energy dense, while foods with a high water content will have low energy density. For example: Food Oil, fat Peanuts Rice Ice cream Oranges Lettuce, mushrooms

Energy Density (g/kg) 37 24 5.2 3.8 1.5 0.5

Energy expenditure Think of all the ways that your body expends energy and record them below: 1. 2. 3. 4. 5.

Ingested energy Digestible energy Metabolisable energy Net energy value Stored energy

Read Components of energy expenditure (pages 234-237) and adjust your list accordingly. It is important that you have a clear understanding of each of the components of energy expenditure. Develop a definition for each of the terms below. Adaptive thermogenesis Thermic effect of food TEF Thermic effect of activity (TEA) Basal metabolic rate (BMR) or basal energy expenditure (BEE Component of energy expenditure Basal metabolism

Definition Used interchangeably, essentially the same thing Amount of energy expended while at rest BMR = rate of EE in post – absorptive state (1214 hours after eating), at rest, in ambient temperature, while lying down. BEE is extrapolated from BMR over a 24 hour period Any bodily activity that enhanves or maintains physical fitness and overall health and wellness.

Physical activity

Thermic effect of food

Amount of energy expenditure above the resting metabolic rate due to the cost of processing food for use and storage

Adaptive thermogenesis

Decrease in energy expenditure beyond what could be predicted from body weight or its components under conditions of standardized physical activity in response to a decrease in energy intake.

The thermic effect of food is considered in many popular diets. What percentage of the energy consumed is expended with the thermic effect of food (page 235)? Which macronutrient has the highest relative thermic effect of food (page 237)?Protein receives the highest relative thermic effect of food. (20%-30% of total daily energy intake) The basal metabolic rate (BMR) accounts for approximately two thirds of our daily energy expenditure. There are several factors that impact on an individual’s BMR. Review Table 8.1 Factors that affect the BMR on page 235 (and explanations on page 237 under Estimating energy requirements) and identify which factors either increase or decrease energy expenditure. Factor Age Height Growth

Effect on BMR Decrease Increase Increase

Body composition (gender)

Increase. (higher the BMR

Explanation Due to reduced lean body mass In tall and thin people Due to children, adolescents and pregnant women The more tissue, the higher the

Fever Stresses

which is why males usually have a higher BMR than females Increase Increase

Environmental temperature Fasting/starvation Malnutrition Hormones (gender)

Increase Decrease Decrease Slight increase

Smoking

Increase

Caffeine

Increase

Sleep

Decrease

BMR. The more fat tissue, the lower the BMR Fever raises the BMR Stresses (including diseases and certain drugs) Both heat and cold No food of digestion. No nutrients to function Thyroid hormone thyroxin, e.g. can speed up or slow down BMR. Premenstrual hormones slightly raise the BMR Nicotine, drug reduces stress and can function properly for a slight period of time Caffeine increases energy expidenture BMR is at lowest

When we estimate energy expenditure, we do not account for the thermic effect of food and adaptive thermogenesis. Why not (page 237)? The figures are not clear as the values range between one value to another. Methods of measuring energy expenditure Uhow is energy expenditure determined? Total daily energy expenditure can be measured in the laboratory or estimated using prediction equations. 3 types of measurement, indirect calorimetry direct calorimetry and non- calorimetric methods. Energy expenditure can be estimated using direct calorimetry, indirect calorimetry, or noncalorimetic methods. Direct calorimetry involves continuous measurement of gaseous exchange in subjects confined in metabolic chambers. This very accurate method measures the amount of heat released to calculate energy expenditure. Individuals reside within the chamber for a period of 24 hours. See the image

below for an example of the interior of a metabolic chamber.

Indirect calorimetry can be performed either at rest or during exercise, and measures the rate of oxygen consumption and carbon dioxide production. This method can estimate the energy expended in a given situation, but is not a suitable representation of total daily energy expenditure. See the image below for an example of indirect calorimetry measuring gas exchange during exercise.

Non-calorimetric measures of energy expenditure use other methods to estimate energy expenditure. These measures are less accurate, but more practical and cost-effective than direct and indirect calorimetry. Common methods include heart rate, doubly-labelled water, and the factorial method.

The factorial method of estimating energy expenditure uses calculations and activity tables to estimate energy expenditure. The Schofield equation is used to predict basal metabolic rate. Refer to Table F.1 on page 695 for an equation to determine your basal metabolic rate.

(MJ/day) = megajoules 1 MJ = 1000 Kj Sex Male

Females

Age 10-18

Equation

(0.074 x wt) + 2.754 = BMR

18-30

(0.063 x wt) + 2.896 = BMR

30-60

(0.048 x wt) + 3.653 = BMR

Over 60

(0.049 x wt) + 2.459 = BMR

10-18 18-30 30-60 Over 60

(0.056 x wt) + 2.898 = BMR (0.062 x wt) + 2.036 = BM (0.034 x wt) + 3.538 = BMR (0.038 x wt) + 2.755 = BMR

My basal metabolic rate: To estimate total daily energy expenditure, your BMR needs to be multiplied by a factor representing your energy expenditure. Table F.2 on page 695 lists the Physical Activity Level (PAL) factors. Review the list and select the PAL that applies to you. Hint: if you attend classes but are otherwise inactive, your PAL is 1.4. Add an addition 0.3 for each 30-60 minute session of sport you participate in each day. My PAL is: Physical Activity level – expressed as a ratio of total energy expenditure to BEE Record of total time (minute/day) spent in each of the various daily activities. Individual acitivities have an estimated energy (metabolic) cost. Metabolic cost of activites called METs are available for different activities. (MET= multiples of an individual’s oxygen uptake). To calculate your estimated total daily energy expenditure, multiply your BMR by your PAL. x We will use a more detailed method to estimate energy expenditure for Assessment Task 1. For this task, you will be required to record the time spent in all activities over the course of a 24 hour period. Each of these activities has an energy cost (see Table 1 below). The energy cost of these activities can be tabulated (see Table 2 below) and then added to the BMR to calculate estimated energy expenditure. Many students have had difficulty completing this aspect of the task, so please

try this well in advance of the due date to leave time for asking questions on the LMS discussion board. Table 1. Energy Cost of Activities (modified from Table 7.11, Guthrie, 1989) Activity code

Activity

Energy Cost kJ/hour/kg body weight

B

Boxing

CP

Carpentry (heavy)

CYM

Cycling at moderate speed approx. 10km/hr

10.5

CYF

Cycling at fast speed approx. 25km/hr

31.8

DS

Dancing slowly

12.6

DQ

Dancing quickly

15.9

C

Dressing and undressing

2.9

D

Driving

3.8

E

Eating

1.7

FE

Fencing

F

Football

HRW

Horse riding

HRT

47.7 9.6

30.5 4.0 (approx) - walk

5.9

- trot

18.0

LW

Laboratory work

3.4 (approx)

L

Lying still, awake, e.g. watching television

0.4

P

Painting

6.3

FP

Peeling potatoes – standing – other food prep

2.5

PPS

Piano playing

- slow

3.3

- fast

5.9

PPF TT

Table tennis

18.4

R

Reading

RO

Rowing in a race

67.0

RU

Running

29.3

SE

Sewing

1.7

1.6

SG

Singing (loudly)

3.3

SI

Sitting in lectures, sitting in a car or on public transport

1.7

SK

Skating

SL

Sleeping

SQ

Squash

ST

Standing

2.1

SF

Sweeping floor

5.9

SW

Swimming

33.0

T

Tennis

18.0 (approx)

TY

Typing (rapidly)

V

Vacuuming

VP

Violin playing

2.5

WS

Walking leisurely (4-5km/h), walking the dog (depends on dog!)

8.4

WR

Walking at reasonable pace (6-6.5km/h)

14.2

WQ

Walking quickly or up incline (7.5-8.5km/h)

38.9

WD

Walking

- downstairs

0.05 /15 steps

- upstairs

0.15 /15 steps

WU WT

14.6 0 30.0 (approx)

4.2 11.3

Writing

1.7

Table 2. Activity calculations for daily energy expenditure in physical activity Activity = A

Hours spent on activity = H

Energy cost per activity Energy expended =E (H x E x kg) kJ (kJ/kg/hour)

Running

1H

29.3v

1465

24-hour total Estimated Energy Expenditure (EEE) (kJ) – add subtotals

kJ/day

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