Assessment of Nutritional Status - Anthropometry Flashcards

1
Q

Describe ‘anthropometry’.

A

The study of body measurements
including:
- taking, recording and analysing body measurements

The breakdown of your body’s make up:

  • lean mass
  • fat mass
  • bone
  • water %
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2
Q

Why is anthropometry important?

A
  • Understand fat distribution
  • Identify and understand wasting
  • Estimate energy requirements of individuals
  • Predict the effects of weight loss/gain on body tissues
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3
Q

List some factors that affect body composition

A
  • Gender
  • genetics
  • diet
  • Age
  • level of physical activity
  • health status
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4
Q

describe the two compartmental model

A

body is made up of

  • lean body mass LBM (or fat free mass FFM)
  • fat mass
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5
Q

describe lean body mass

A

the weight of all components of the body except fat (e.g., bone, muscle, water).

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6
Q

describe fat mass.

A

the fat compartment in the body

20% water and 80% adipose tissue

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7
Q

What are the body fat ranges for a female aged 20-39?

A
underfat = 0-21%
healthy = 21-33%
overfat = 33- 39%
obese = 39%+
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8
Q

what are the body fat ranges for a male aged 20-39%

A
underfat = 0-8%
healthy = 8-19%
overfat = 19-25%
obese = 25%+
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9
Q

List the main methods of measuring body composition

A
Anthropometry
bio-electrical impedance 
densitometry 
total body water 
total body potassium 
MRI 
DEXA
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10
Q

Why can total potassium content be used to measure body composition?

A

Fat free mass has a constant proportion of potassium.

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11
Q

What does densitometry measure and how?

A

Fat mass and fat free mass

Requires measure of total body mass as whilst the weight of FM is relatively constant, the mass of LBM varies according to composition.

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11
Q

What does densitometry measure and how?

A

Fat mass and fat free mass

Requires measure of total body mass as whilst the weight of FM is relatively constant, the mass of LBM varies according to composition.

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12
Q

Describe ‘BMI’

A

Body mass index
Weight (Kg)/Height^2 (m)

predicts fatness and health status

aims to correct individuals weight, in relation to their height

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13
Q

Describe the BMI categories for adults

A
underweight - less than 18.5
healthy/normal - 18.5-24.9
overweight - 25-29.9
obese class 1 - 30-34.9
obese class 2 - 35-39.9
obese class 3 - 40+
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14
Q

Why is BMI so widely used?

A

crude indicator of weight judgement (WHO)
BMI highly correlates to fat mass for most individuals e.g., not athletes
good predictor for body fat %

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15
Q

Describe the relationship between BMI and mortality rate

A

‘U-shaped curve’

underweight - high risk 
lower healthy range - low risk 
healthy - minimal risk 
higher healthy range - low risk 
overweight - moderate risk 
obese - high risk 
upper limit of obese - extremely high risk
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16
Q

How is ‘waist circumference’ measured?

A

tape measure on bare skin

measure of girth at the midpoint between the lower rib and iliac crest

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17
Q

What are some pros and cons of waist circumference?

A

Pros

  • quick, inexpensive and easy
  • effective at assessing risk in ppl with BMI between 25-34.9

Cons

  • cultural insensitivity
  • room for error = low reliability
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18
Q

What body components does waist circumference measure?

A

both abdominal subcutaneous and visceral adipose tissue

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19
Q

Why is Waist Circumference an effect marker of disease?

A

high WC = high central adiposity i.e., fat around central organs

excess amount of fat around abdomen that is disproportionate to total body fat is a marker of diseases associated with obesity, and metabolic syndrome

even with healthy BMI, high WC indicates disease risk

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20
Q

What is the desirable WC for males and females?

A

Males - less than 94cm

females - less than 88cm

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21
Q

Describe ‘Waist to hip circumference ratio’§

A

A measure used to describe the distribution of subcutaneous and intra-abdominal adipose tissue

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22
Q

What are some pros and cons of WHR?

A

pros

  • minimally invasive
  • cost effective
  • can identify fat dist. type e.g., gynoid (pear) or android (apple)
  • associated with disease risk in both men and women

cons
- WHR doesn’t change if both Waist and hip measurements change

23
Q

What are the desirable WHR’s for men and women?

A

Men - less than 0.9

Women - less than 0.8

24
Q

How do you calculate frame size?

A

R = H/C

r = ratio of height to wrist circumference 
h = height (cm)
c = circumference of wrist (cm)
25
Q

How is skinfold thickness measured?

What does it measure?

A

measured using a skinfold caliper

measure of body fat - used to calculate body fat %

26
Q

What is the basic principle/assumption behind the skinfold thickness measure?

A

there is a constant relationship between subcutaneous and internal fat

total body fat can be estimated by measuring subcutaneous adipose tissue

27
Q

How does the skinfold thickness measure differ between males and females?

A

females have more internal fat than males

age and gender specific predictions need to be used to assess total body fat estimation from skinfold thickness

28
Q

what are some common skinfold thickness sites?

A
  • thigh
  • chest
  • abdomen
  • calf
  • triceps
  • subscapular
29
Q

What are some disadvantages of the skinfold thickness measure?

A
  • requires level of expertise i.e., trained professional, to avoid error
  • requires partial undressing which means difficult to do on bedridden patients
30
Q

How is error in skinfold thickness measurements reduced?

A

sum of multiple body parts is calculated to reduce error in the measurement itself

also corrects for differences in subcutaneous body fat at different sites

31
Q

Why is the correlation between subcutaneous fat and total body fat higher in elderly patients?

A

elderly have higher amount of internal fat than younger people

32
Q

Which patients would not be suitable for skinfold thickness measurement?

A

Obese
HIV patients
patients with oedema

33
Q

What is air displacement plethysmography?

A

patient sits inside a chamber of a known volume and the body volume is equal to the reduction in chamber volume

34
Q

What is the principle behind electrical conductance?

A

assessing body comp based on marked differences in electrolyte content between different body compartments e.g., FM and FFM.

e.g., FFM contains sodium, potassium, chloride and bicarbonate
FM contains low levels of these electrolytes

FFM has better conductivity than FM

35
Q

What are the two methods of electrical condiuctivity?

A
  • bioelectrical impedance

- total body electrical conductivity

36
Q

How does bioelectrical impedance work?

A

electrical current passes through body

  • is repelled by fat (non-conducting tissue)
  • is transmitted through electrolytes in water (found in FFM)
37
Q

what are some pros and cons of bioelectrical impedance?

A

Pros

  • quick
  • easy
  • safe

Cons

  • dehydration can result in overestimation of fat mass
  • not suitable in pregnancy
38
Q

What is DEXA used for?

A

to measure bone mineral density

to diagnose osteoporosis

39
Q

How do you measure weight and height in children?

what are the UK clinical categories/cut offs?

A

height and weight = BMI
BMI/age = percentile

undernourished = BMI < 2nd percentile
overweight = BMI > 91st percentile 
obese = BMI > 98th percentile
40
Q

Describe when head circumference is used and what does it measure?

A

Children
aged 0-2 years
measurement compared against growth charts
measure of mental development and growth

41
Q

How should weight measurements be taken?

A

same time every day
fasted
bladder/bowel emptied

42
Q

How can you ensure accuracy when using spring balanced scales?

A

scale on a hard, flat surface
check scale is on zero before weighting ppt
ppt to stand in the middle of scales and look ahead
record at same time every day

43
Q

Describe the Frankfurt plane method of taking height measurement

A

ppt is positioned so that the frankfurt plane is horizontal

feet together

knees straight

heels, buttocks and shoulder blades against the vertical surface of the stadiometer.

44
Q

How do you measure hip circumference?

A

position tape around the maximum circumference around the buttocks

45
Q

how do you calculate waist to hip ratio?

A

Divide waist measurement by hip measurement

46
Q

What are the healthy WHR’s for men and women?

A

women - <0.8

men - <0.9

47
Q

What are some considerations to take into account before taking measurements of any kind?

A

Gain consent from patient
Explain that may need to remove shoes/heavy clothing, is this okay?
Take into consideration any disabilities e.g., wheelchair user

48
Q

What are the BMI cut off points?

A
underweight - < 18.5 
normal - 18.5-24.9
overweight - 25 - 29.9
obese class 1 - 30-34.9 
obese class 2 - 35-39.9 
obese class 3 - 40+
49
Q

How can you set up the equipment properly to ensure a reliable weight measurement?

A

scales on hard flat surface
calibrated
set to zero before measurement takes place
subject stands in a relaxed upright position and looks ahead
take measurement 3x and take the average
measure to nearest 0.1kg
take measurement at same time of day
fasted, after bladder emptied

50
Q

How can you set up the equipment properly to ensure a reliable height measurement?

A

stand so that the Frankfurt plane is horizontal
even, level surface
ppt to take deep breath and stand tall
read measurement to nearest 0.1cm
arms hang loose and relaxed, palms facing thighs
shoulders relaxed

51
Q

For which ethnicities are there different BMI cut offs?

A

asian, african carribbean & black african

52
Q

Describe waist circumference measurement

A
  • midpoint between the lowest rib and the iliac crest
  • demonstrates fat distribution
  • good indicator of health and risk as central adiposity is a risk factor of metabolic diseases such a CVD
53
Q

How do you take a waist circumference measurement?

A
  • Gain consent beforehand
  • ideally tape measure should be against bare skin
  • ppt to breathe out normally
  • tape measure should be snug but not digging into the skin and not loose
  • read measurement to nearest 0.1cm
  • repeat measurements to ensure accuracy
54
Q

what are the healthy body fat ranges for men and women?

A

women - 21 - 33%

men - 8 - 19%

55
Q

What are the UK BMI clinical cut offs for children?

How is it assessed?

A

comparison between age and BMI and plotted on a percentile chart

underweight = BMI < 2nd percentile 
overweight = BMI > 91st percentile 
obese = BMI > 98th percentile
56
Q

What is a percentile chart? How is it used to assess growth of a child?

A

Percentile growth chart is a comparison of a child’s size compared to their age, compared to those of other children of the same age/maturity who have shown optimal growth.