Lab class 3: Body comp assessment Flashcards
What does body composition measure
relative percentage of body mass which is fat and fat free tissue
what conditions does excess body fat increase the likelyhood of developing
cancer
diabetes
CVD
Name some anthropometric methods of determining body composition
BMI
waist circumference
waist to hip ratio
skin folds
Name some denistometry methods of determining body composition
hydrostatic weighing
plethysmography weighing
Name ‘other’ methods of determining body composition
MRI
DEXA
bi-electrical impedance
what are the scores on BMI which class people as overweight and obses
25+
30+
explain the potential limitation of using BMI as a measure of body compostion
doesn’t distinguish between fat mass and fat free mass
muscular people may be defined as obese
also doesn’t consider where the fat mass is located
why is waist circumference a good measure for determining a person risk of developing disease
marker of central obesity and visceral fat
central fat is a more potent risk factor for disease than generalised body fat
marker for disease development even if person is normal weight
what waist circumference defines high and very high risk for males and females (cm)
high = 90-110 females 100-120 males
very high = >110 females >120 males
what is a limitation of using waist circumference to measure body compostion
doesn’t give a percentage body fat
explain the concept behind using skin fold measurements
subcutaneous fat amount correlates well to total body fat
what is the critique of using skin fold measurements
need familiarisation and practice to get valid results
user dependent
not ideal for very lean or very dense people
how does densitometry calculate body composition
measures whole body density
estimate body composition using the ratio of body mass to body volume
so these methods are used to measure body volume
gives a value for body density which can then be used to estimate % body fat
explain how bielectrical impedance estimates % body fat
based on an estimation of total body water
small electrical current passed through body
will flow through parts of body mostly composed of water e.g blood, urine and muscle
more fat = more resistance
give some limitations of using bielectrical impedance
affected by hydration status and recent activity
doesn’t account for location of fat
underestimate lean and overestimate obese
