Lecture 4: Body composition and health Flashcards
What is the study of body structure and composition?
Anthropometry
- it looks at: height, weight, body lengths, breadths, circumference, somatotypes, body composition, and relationship to health and sport
What are somatotypes?
- calculated from body structures and measurements
- use to provide a score on each somatotype scale
- most people are a combination of three rather than a single somatotype\
- data is plotted on a somatochart or somatomap
Somatotypes and its Relationships to health: ENDOMORPH
- shortest lifespan
prone to CVD and some postural problems
(Leg deformities, knock knees, flat feet, everted feet)
Somatotypes and its Relationships to health:ECTOMORPHS
- longest living
- have the most postural problems
- (Vertebral column problems most common)
eg. round shoulder, kyphosis, lordosis, and scoliosis
Somatotypes and its Relationships to health: MESOMORPHS
- cope best with physical work
- have the least postural problems
Storage fat is mostly ________
- subcutaneous
- Energy stores:
M - 12% and F - 15%
The relationship to mortality and morbidity is associated with more __________ than total body mass relative to height. (This a limitation of BMI)
- FAT MASS
What is essential fat?
- bone marrow, spinal cord, liver, spleen, kidney and others
- 3% of BW for M and F 4-7%
- sex specific fat for females (stored in breasts, pelvis, buttocks, and thighs)
With regards to body composition measurements, what measurement can be done from cadavers only?
- Direct measurements
What is the gold standard for body composition?
Hydrostatic weighing AKA densitometry or underwater weighing
- it is based on the effects of body density on weight measured in water (Fat being less dense than muscle)
The use of imaging techniques for body composition… what are its limitations
- limitations of Imaging is it is expensive and it exposes you to radiation
- Some imaging techniques include Ultrasound, MRI, x-ray, CT and DEXA
Another type of body composition measurement which uses air displacement and mass body…(Indirect measurement)
- Air densitometry (BodPod)
- suggested to be the new reference method, it is reliable but validity is still being questioned
What are bioelectrical impedance methods?
- they are based upon electrical current and will have less resistance to current flow through tissue with high water and electrolyte content (fat decreases current flow)
- Results are SENSITIVE to persons HYDRATION STATUS AND SKIN TEMPERATURE
- Take note that they often overestimate fat in athletes and underestimate fat in obese
These are contact tension calipers used to measure subcutaneous skinfold thickness at multiple sites of the body…
Skinfold Thickness Measurements
- reliable
- cost effective
- provide information about fat mass and distribution of fat
- best in leaner population
- con be converted to body fat % due to associations between subcutaneous fat, internal (visceral) fat and whole-body density (Conversion formulas are population specific)
What is girth measurements?
- circumference measurements of six body sites obtained
- % body fat prediction equations used to convert measurements to % BF
- equations are age and sex specific
- RELIABLE BUT NOT VALID with many population groups (can’t tell fat from muscle)
What are the wait to hip ratio values?
Waist/hip = ratio
Desirable M <0.85 and F <0.75
Health risk (WHO) M>0.90 and F>0.85
Dietitians Association of Australia M>0.90 and F >o,80
Note: WHO suggests that W:H is better predictor in older people >75 than waist or BMI
What are the wait circumference values?
CAUCASIAN
Desirable M <90 and F<75
Overweight M (94-101.9) and F (80-87.9)
Obese M >102 and F >88
ASIAN
Overweight M>90 and F>80
What is BMI?
Body Mass Index
- Weight in kg
- BMI = weight/height^2 (kg/m^2)
- widely used in epidemiology studies
What is energy balance?
- a failure to achieve energy balance contributes to changes in body composition
(Energy input: Proteins, lipids, carbohydrates)
(Energy output: TEF, Physical Activity, Resting metabolism)
If energy balance is maintained _____
body weight is maintained
If energy balance is positive _____
body weight (and usually adipose tissue) increases
If energy balance is negative _______
body weight decreases
What are the three components of Total Daily energy expenditure? (TDEE)
- Resting metabolic rate (60-75%)
- sleeping metabolism
- Basal Metabolism
- arousal metabolism
- Thermic effects of feeding (10%)
-Thermic effects of physical activity (15-30%)
Is the minimal energy needed to maintain vital functions in the AWAKE state
- Basal Metabolic rate
Basal Metabolic rate is measured under very specific standardised conditions
What is the energy required to maintain vital functions plus digestion
Resting metabolic rate
Note: RMR AND BMR vary in proportion to a person’s body surface area
Basal metabolic rate measurements (Information, tap card)
- Conditions:
- after a 12 hour fast and a restful night’s sleep
- awake for 30-60 minutes and resting
- no exercise since waking
- environment: Temperature (25 degrees), Barometric pressure - sea level, Humidity 50%
Units of measurement:
- Relative to body surface area (done during at rest)
- Relative to body weight (done during exercise)
What influences RMR?
- Thyroid hormones (higher levels increase RMR)
- Sex M>F
- Fat free (lean body mass) - higher with more skeletal muscle
- Protein Turnover (higher with more protein turnover
- age
- climate
- fever
- nutritional status
- Health status
Is the energy required to maintain body temperature and for digesting, absorbing, and assimilating food
- usually peaks 1 hr after eating
- influenced by nutrient content of food
- usually greater with higher protein content
- 30% dependent on thyroid hormone levels
- Obligatory thermogenesis
This is the thermic effects of activating sympathetic nervous system e.g. when cold
(Shivering
- heat from skeletal muscle activation or brown adipose tissue to maintain body temperature
- Facultative thermogenesis
1 MET (Metabolic Equivalents of Tasks) =
resting energy expenditure
- PA has potential to have the greatest impact on TDEE
- most people can sustain PA levels x 5 RMR (5METS)
- most people should be able to sustain PA levels 10xRMR
- elite endurance athletes able to sustain PA levels 20xRMR
- Endurance athletes may have TDEE double normal person due to training
What Influences RMR?
