Lecture 2

Question 1

Two-component model

Answer 1

Fat mass (FM) + fat-free mass (FFM)

Question 2

Three component model

Answer 2

Fat mass (FM)+ fat-free mass (FFM)

Fat free mass (FFM)=
- Bone mineral content (BMC)
- Bone-free fat-free mass

Question 3

Weight alone can be very misleading

Answer 3

Doesnt tell us how much of the weight of fat free mass and where is it stored

Depends on how much muscle

Question 4

Why measure body composition

Answer 4

-Health
-Sports performance
-Monitoring growth
-Assessing response to intervention
-Creation of reference values
-Population monitoring

Question 5

Total Body Composition

Answer 5

% fat= (FM/body weight) x 100
%FFM= (FFM/body weight) x 100

Question 6

Regional Body composition

Answer 6

Is fat stored primarily in the central or peripheral regions?

Question 7

Health risks of obesity depend on …

Answer 7

Regional fat distribution as well as total body composition

Question 8

There are two types of bodies

Answer 8

Central (apple)= Android
Peripheral (Pear)=Gynoid

Question 9

Which one of the two body types is the most concerning for health

Answer 9

Central

Question 10

Central adiposity increases health risks such as?

Answer 10

type 2 diabetes
Coronary heart disease
Cardiovascular disease
Arthritis

Question 11

Central fat=visceral

Answer 11

Intra abdominal

Question 12

Subcutaneous

Answer 12

under the skin fat

Question 13

What fat increases health risks the most

Answer 13

visceral fat

Question 14

When measure regional fat distribution ideally want to measure

Answer 14

Visceral fat

Question 15

Visceral fat is more

Answer 15

metabolically active

Question 16

Many different methods some measure … and others measure …… and some measure both

Answer 16

Total body composition

Regional body composition

Question 17

Two component model explanation

Answer 17

measure either FM or FFM and calculate the other from total body weight

Question 18

Assume composition of FFM is constant which is

Answer 18

Not always true- there are always going to be an issue with what method you use

Question 19

Three main types of approach for two-component model

Answer 19

1) Densitometry

2) Electrical resistance of the body

3) External measurement

Question 20

Densitometry

Answer 20

1- Underwater weighing
2- Air displacement plethysmography

Question 21

Electrical resistance of the body

Answer 21

Bioelectrical impedance analysis

Question 22

External measurement

Answer 22

Anthropometry

Question 23

Density

Answer 23

Mass/volume

Question 24

Equations have been developed that allow us to calculate ………… then FFM

Answer 24

% fat from total body density

FFM can then be calculated by difference

Question 25

Densitometry- assumptions

Answer 25

-The density of fat free mass is constant -The density of fat does not vary amoung people -The water content of fat free mass is constant -The proportion of bone to fat free mass is constant

Question 26

Underwater weighing

Answer 26

The amount that has been displaced You breath out as much as possible (you get emersed for 7 seconds and then you have to do this for about 4 to 12 times)

Question 27

Underwater weighing: Calculation 1

Answer 27

Body volume Mass(air) -mass(water)-RV-100 / body volume

Question 28

Underwater weighing: Calculation 2

Answer 28

Body density Mass(air) / body volume

Question 29

Underwater weighing: Calculation 3

Answer 29

% body fat =((4.95 / body density)- 4.50) x 100

Question 30

Underwater weighing: Advantages

Answer 30

-Gold standards -Accurate -2% error

Question 31

Underwater weighing: Disadvantages

Answer 31

-Density of FFM not necessarily uniform -Do 4-12 times -Not suitable for all -Breathing apparatus to measure lung volume -Bulky equipment

Question 32

Underwater weighing is known as a ...

Answer 32

"Gold standard"

Question 33

Air displacement plethysmorgraphy

Answer 33

-For example: the BOD POD -Similar principle to underwater weighing -Except calculate displaced air rather than displaced water when person is in and out of chamber -Practical advantages compared with underwater weighing

Question 34

Bioelectrical impedance analysis

Answer 34

Body conducts electricity through FFM Pass weak current through body and measure impedance (resistance + reactance) to current

Question 35

Bioelectrical impedance analysis: Validity can be impacted by:

Answer 35

-Hydration status -Recent physical activity -Consumption of food/drink -Menstrual status -Body position

Question 36

Bioelectrical impedance analysis: Good practice

Answer 36

-Avoid alcohol & vigorous exercise 24-48 hours before -Measure >-2 h after eating and within 30 min of voiding -Subjects lie down, with limbs not touching body Improve measurement by adding sex and age

Question 37

Practice the calculations

Answer 37

1) Total body water 2)Fat free mass 3)Fat mass 4)Body fat %

Question 38

Bioelectrical impedance analysis: Advantages

Answer 38

-Simple -Cheap -Portable -Suitable for all ages

Question 39

Bioelectrical impedance analysis: Limitations

Answer 39

-Need to be fasting -Control recent activity & hydration status -Need appropriate equation for your participants

Question 40

Anthropometry

Answer 40

-Most widely used method -BMI, skinfolds, circumferences, breadths

Question 41

Anthropometry: Interpret by

Answer 41

-Comparing results with reference data: percentiles or standard deviation score (Z-score) -Using cut offs that relate to risk (morbidity, malnutrition)

Question 42

Anthropometric Reference Data

Answer 42

Data need to be developed from group representative of healthy population-need to be specific (age, gender, ethnicity) Often presented as percentiles

Question 43

Percentiles

Answer 43

Describe the position of the measurements in relation to the measurements in relation to the measurements for a population NB: At the 50th percentile 50% of the population are below that value and 50% are above

Question 44

Anthropometry: Advantages

Answer 44

-Simple -Safe -Noninvasive -Cheap -Portable equipment Commonly used for large studies

Question 45

Anthropometry: limitations

Answer 45

Less accurate so less sensitive to change Potential sources of error: - Measurement error -Variation in tissue composition -Assumptions may not be valid in disease states or obesity