Body Composition

Question 1

Children- growth charts

Answer 1

Allows a child’s physical development (size and growth) to be compared to that of other healthy children of the same age and gender.
Based on large scale cross sectional surveys

Based on measurements of babies and children from a certain population. Length measured when baby is lying down, height only measured when child is standing.

Question 2

Waist and hip circumference

Answer 2

Body fat distribution can influence risk factors for a number of diseases. Abdominal obesity is increasingly recognised as a major risk factor for CVD. Compared with BMI, waist circumference, waist-hip ratio appear to be more strongly associated with metabolic risk factors, incident CVD events and death. Attributed to the presence of visceral adipose tissue which promotes insulin resistance, dyslipidaemia and hypertension

Question 3

Skin folds

Answer 3

Measures the thickness of a double fold of skin and compressed subcutaneous adipose tissue - estimation of body fat percentage
Measured in mm
Most commonly: bicep, tricep, subscapular, abdominal, medial calf, front thigh
Adv:
Inexpensive
Measures easy and quick to obtain when trained
Quite accurate when done correctly

Question 4

Skin fold assumptions

Answer 4

The double thickness of skin and subcutaneous fat tissue has constant compressibility
Thickness of the skin is negligible or a constant fraction of the skin fold
The thickness of the subcutaneous fat tissue is constant or predictable within and between individuals
The fat content of adipose tissue is constant
The proportion of internal to external fat
Is constant
Body fat is normally distributed

Question 5

Bioelectrical impedance (BIA)

Answer 5

Determined the electrical impedance, or opposition to the flow of an electric current through body tissues which can then be used to calculate an estimate of total body water
Total body water can be used to estimate fat free body mass and by difference with body weight, body fat
Adv:
Simple, cheap after initial investment
Disadvantages:
Not standardised, influenced by body fluid, cheap may mean high degree of error

Question 6

Underwater weighing

Answer 6

Hydrodensiometry
Difference if individuals weight on land vs weight submerged in water- volume
Mathematical eqn using volume and weights on land provides us with body density and this can be used to calculate % body fat

Question 7

BodPod

Answer 7

An air displacement plethysmograph which uses whole body densiometry to determine body composition (fat and fat free mass) in adults and children
Same operating principle as hydrostatic weighing, except that is uses patented air displacement plethysmography instead of water,
For highly accurate, fast and safe results
Also proves RMR, total energy expenditure

Question 8

DEXA

Answer 8

Dual energy X-ray absoptiometry is medical imagining scanner. The standard equipment doctors use to test for osteoporosis.
Full body scan from
Head to toe, provides detailed images of the bones, lean body mass, body fat of participants.
Subjects Lay flag on a raised padded bed while a scanning arm moves slowly over them.
There is low radiation exposure.

Question 9

Other clinical/ physical signs of nutritional status

Answer 9

Wasting 
Oedema
Dehydration 
Skin issues 
Eyes
Mouth/ gums / tongue

Question 10

Body fat distribution

Answer 10

Some people need less body fat

• fat for fuel
• insulation and protection
• assist in nerve impulse transmissions
• fat to support normal hormone activity

More body fat:

• thresholds differ among individuals
• thresholds differ for each function

Intra- abdominal fat around abdominal organs may be critical.
Central obesity is excess fat around the trunk of the body. Also called abdominal fat or upper- body fats. Associated with increased risks.

Question 11

Anthropometry

Answer 11

The measurement of body size, weight and proportions 
Can be used to monitor/ assess: 
Health 
Development and growth
Nutritional status 
Body composition