Lecture on body composition, particularly focused on skinfold measurements

1. Anthropometry
measurements

2. Why anthropometry?
Fast and cheap means in clinical diagnostics:
- growth problems
- overweight in children
- malnutrition
Important in assessing health of populations:
- screening
- health surveillance
- epidemiologic studies

3. Advantages
• Anthropometric measures are indicators of
 past exposures (e.g. past malnutrition leads to low height)
 future events (e.g. high waist circumference is a risk
factor for cardiovascular diseases)
• fast
• simple
• non-invasive
• relatively cheap

4. Limitations
Relatively insensitive towards distrubances in
nutritional status over short period of time
Impossible to detect specific nutrient deficiency
Protein
deficiency?
Nutrient
deficiency?
(e.g. Zinc)
Stunted child
Energy
deficiency?

5. Two types of anthropometric
measurements
1. Measurements that assess body size
Height
Head circumference
Knee height
Arm span
Elbow breadth
Weight
2. Measurements that assess body composition
- measurements of body fat (Skinfold thickness, BIA, waist)
- measurements of fat-free mass (BIA, Densitometry)

6. Height
In children:
•Indicator of stunting: insufficient growth
because of nutritional deficits
•Needed to calculate indices of body
composition: e.g. BMI, waist-height-ratio
In adults:
•Needed to calculate indices of body
composition: e.g. BMI, waist-height ratio

7. Equipment
1. Stadiometer
2. Microtoise

8. Sequence
1. Person should be > 2 years old
2. Person should wear only light clothes, no shoes
and no socks
3. Person steps on Stadiometer
•
Feet together and flat on the floor
•
Knees straight
•
Heels, buttocks and shoulder blades in contact with vertical
surface of the stadiometer/wall
•
Shoulders relaxed, palms facing thighs
•
Head not necessarily in contact with the vertical surface and
in Frankfurt Plane

9. Frankfurt plane

10. 4. Subjects are asked to take a deep breath and
stand tall to help straightening the spine
5. Lower headboard and press down the hair
6. Measure taken at expiration
7. Eye of examiner on level with headboard

11. Time of day
Height decreases during the day due to
compression of the spine
 Always note the time of the day and try
to measure at the same time of day for all
subjects or when doing repeat
measurements

12. Waist circumference
• Measures abdominal fat (subcutaneous + intraabdominal).
• Excess abdominal fat is associated with risk of
cardiovascular and metabolic disorders.
• Greatly increased risk:
Men: > 102 cm
Women: > 88 cm
• Waist-hip ratio:
According to WHO.
Applies to adults.
Men: < 1.0
Women: < 0.85
• Waist-height ratio:
Waist/height should be less than 0.5 (Adults and children)

13. How to measure waist
circumference
• The patient should stand straight, relaxed, with the
arms at the sides and feet together pointing forward
• Find the iliac crest and mark with pen
• Find the lowest rib margin and mark with pen
• Measure the distance between the marks and mark
the middle
• Face the patient and place the tape horizontal at the
middle mark. Make sure it is horizontal all the way
around
• Measure at the end of a gentle expiration. Measure
to the last completed unit (the last line you can
actually see on the tape)

15. Sources of error
• Patient could have problems standing still or be
very ticklish.
• Difficulty in finding the iliac crest or lowest rib
margin.
• Patient could intentionally depress abdomen.
• Measuring waist is practical but needs practice
and standardization.

16. Sagittal diameter
Measures abdominal fat.
The distance between the examination table and
the highest point of the abdomen in the supine
position
Less studied than
waist circumference
Men < 22 cm
Adults
Women < 20 cm
Sagittal Abdominal Diameter as a Screening Tool in Clinical Research: Cutoffs for Cardiometabolic Risk.
J Obes. 2010; 2010: 757939.

17. Two types of anthropometric
measurements
1. Measurements that assess body size
Height
Head circumference
Knee height
Arm span
Elbow breadth
Weight
2. Measurements that assess body composition
- measurements of body fat (Skinfold thickness, BIA, waist)
- measurements of fat-free mass (BIA, Densitometry)

18. Fat and fat-free mass
FAT MASS
~26.9% (women), ~ 14.7% (men)
Mineral
Protein
FAT-FREE
MASS
Water
e.g. BMI, Densitometry (BodPod, Underwater-weighing), Skinfold
Thickness, BIA, waist-hip ratio

19. Indices
Often not raw measurements are used but indices:
•Body Mass Index (weight/height2),
•Waist-Hip-Ratio
•Waist-Height-Ratio
•Mid-upper-arm muscle circumference
(mid upper arm circumference – π*triceps skinfold
thickness)
•Growth indices:
head circumference for age, weight-for-age, weight-forheight, height-for-age

20. Skinfold thickness
Skinfold thickness measurements provide an estimate of the size of
the subcutaneous fat depot, which in turn, provides an estimate of
total body fat
Such estimates are based on two assumptions:
– The skinfold sites selected for measurement, either singly or in
combination, represent the average thickness of the entire
subcutaneous adipose tissue
– The thickness of the subcutaneous adipose tissue reflects a constant
proportion of total body fat
Neither of these assumptions is true, in fact:
– The relationship between subcutaneous and internal fat is nonlinear
and varies with body weight and age (not valid in obese people)
– Variations in the distribution of subcutaneous fat occur with sex, race
or ethnicity and age

21. Measurement sites
(1)
The most commonly used sites are:
– Tricepts skinfold (1): Mid-point of the back of the
upper arm
– Bicepts skinfold: Front of the upper arm, above the
center of the cubital fossa
– Subscapular skinfold (2):below and laterally to the (2)
angle of the shoulder blade, with the should and arm
relaxed. The skinfold should angle 45º from
horizontal, in the same direction as the inner border
of the scapula
– Suprailiac skinfold (3): mid-axillary line superior to
the iliac crest. Picked up obliuquely just posterior to
the midaxillary line and parallel to the cleavage lines
of the skin
– Midaxillary skinfold: picked up horizontally on the
midaxillary line, at the level of the xiphoid process
(3)

22. Calipers
Skinfold thickness measurements are best made using precision
thickness calipers, they measure the compressed double fold of fat plus
skin
Three types of precision calipers can be used: Harpenden (a), Lange (b)
and Holtain (c)
Designed to exert a defined and constant pressure throughout the range
of measured skinfolds and to have a standard contact surface area
The subject should stand erect with feet together, shoulders relaxed and
arms hanging freely at the sides
There is no consensus as to whether the left or right side of the body
should be used

23. Step by step skinfold
measurement
• Generally the measure is done on the left side of the body
• Identify the measurement site and mark it with a pencil
• Keep the caliper in the right hand and pitch the skin with
thumb and index fingers, avoiding pinching the muscle
• Pinch the skinfold with the caliper
• Read the measurement on the caliper
• Open and remove the caliper
• Repeat twice (with at least 2 minutes interval)
• If the second measure differs by more than 10% from the
first, repeat a third time

24. Limitations in measurement
Intra-observer variation:
Occurs when an examiner fails to
obtain identical results on repeated
measurements on the same subjects
Influenced by: measurement site, the
experience of the examiner and can be
reduced by a proper training

25. Limitations in measurement
Inter-observer variation:
Occurs when two or more examiners
measure the same subject and site and get
different results
usually larger than intra-observer variation
can be reduced with training and care

26. Assessing body fat with
multiple skinfolds
No single region of the body can be considered
representative of the whole subcutaneous fat distribution
The optimum combination of skinfold measurement sites
for assessing subcutaneous fat and, by inference, total
body fat has not been extensively investigated, also
considering the different fat distribution among different
people
When estimating body fat, multiple skinfolds are
therefore particularly advisable and generally the mean
measurement between multiple skinfolds is used

27. Electric field
Leg
Trunk
Arm
Bio-impedance
Bioimpedance analysis is based on
the measurement of resistance of
the human body to the passage of
an alternating current at a fixed
frequency of 50 kHz
This is done transcutaneously, via
two surface electrodes (called
primers)
Generator
voltmeter
A second pair of electrodes (called
sensors) has the task of recording
the resistance of the body to the
passage of current. This opposition
to current flow is called impedance
(Z).
The impedance consists of two
components: resistance and
reactance

28. Fat-mass determination with
modern scales
Many modern scales give a
measurement of body fat-mass and
water
This must be considered only an
estimation, also because not all of the
scales are equipped with handles in
order to measure whole body resistance
The estimation of body water is not
proportional to liquid retention as many
firms reports, since this technique is
totally unable to distinguish between IC
and EC water as BIA

30. Thanks!