Body composition & Energy Expenditure Flashcards
what are the major differences in weight, fat and muscles of women and men?
Weight: Men ~13 kg heavier than women Fat: - 15% in men, 27% in women -men 3% of fat is essential, women 27% Muscles: men 44.8% of body weight, women 36% Body density: men 1.07, women 1.04 g/ml
What are some general characteristics about body composition of males vs. females?
- males are usually taller
- males usually weight more
- males usually have a lower total fat % and essential fat %
- males usually have more muscle %
- males have more bone %
- males have a higher average body density (more dense)
What are some factors that would affect body composition?
- age
- gender
- race
- heredity
- stature
what happens to body composition from birth to age 10?
- water decreases from ~70%–> 60% after 1 year
- gradual increase in water until 10 Y (65% in males, 62% in females)
- ECF>ICF during fetal development; ECF:ICF declines with age until ICF>ECF
- lean body mass slows down after birth but then increases slowly but steadily
- water content of LBM in children is higher than that of adults
after what age, weight gain is due to fat deposition?
after age of 25
True or False: Fat deposition is higher in females than males?
True
what are some characteristics of a healthy vs. obese body composition?
obese: much higher fat, less muscles, less organs, less bone (% body mass)
what is BMI? what are the units?
units: B.Wt (kg)/Height2 (m)
BMI= Body mass index: an index of a person’s weight in relation to height, determined by dividing the weight (kg) by the square of the height (m)
what would be a BMI of someone who is underweight?
anything lower than 18.5
what would be a BMI of someone who is overweight? obese?
overweight: from 25-29.9
obese: anything above 30
what is the healthy (normal) BMI range?
18.5-24.9
how does stature affect body composition?
taller individuals have leaner body mass than shorter ones
how does heredity (race) affect body composition?
Blacks (N.America) have leaner body mass and denser bones than whites
how does gender affect body composition?
exists from birth but more apparent at puberty (males have more muscle, more weight, more bone, less fat)
-drastic changes to females in menopause
what are some methods for measuring body composition?
- anthropometry
- densitometry
- absorptiometry
- total body water
- total body K
- there are indirect ways of measuring fat mass & fat-free mass (lean body mass)
How does Anthropometry work ? what assumption does it assume?
Estimates body composition by measuring different circumference and skin fold sites
Assumption: direct relationship between subcutaneous fat and total body fat
what are the 5 sites usually used in Anthropometry?
1- back of the upper arm (triceps) 2- subscapula (man boobs) 3- suprailiac (hips?) 4- Abdomen (gut) 5- Thigh
How does Densitometry work?
Based on measuring body density (specific gravity) and can be measured by dividing body weight in air by loss of weight in water
what is body density?
body density= Wt of body in air/ body wt in air- body wt under water / density of water -RLV
what are the 2 equations to calculate body fat %?
% body fat= (495/body density-450)x100
% body fat= (457/body density-414)x100
body fat wt= body fat %x body wt
lean body weight= body wt- body fat wt
How is total body water measured?
involves the use of isotopes (ex: D2O, 3H2O)
- isotope distributes itself throughout the body water, fluid samples (blood and urine) are collected after 2-4 hours and initial concentration and volume of isotopes= final concentration of isotopse in plasma and volume of body water.
what is the formula used for total body water?
C1V1=C2V2
total body water= V2= C1V1/C2
how is fat free mass calculated?
fat free mass= total body water/ 0.732
how is body fat calculated from total body water?
body fat= total body weight- fat free mass
what is a calorie?
the basic unit of measuring heat energy–> heat energy required to raise the temperature of 1g of water 1 degree (at 15 degree celcius)
how many Joules is one calorie?
1 cal= 4.187J
what is an oxygen bomb calorimeter?
instrument used to measure heat of combustion using oxygen
what is the physiological fuel value of food?
defined as energy available to the body from food, can be calculated by subtracting energy lost in excreta (urine and feces) from energy value of food (gross energy)
what are the physiological fuel values for carbohydrates, protein and fat?
CHO= 4 Kcal/g
Protein= 4 Kcal/g
Fat=9 Kcal/g
what are the components of energy expenditure?
total energy expenditure consists of:
- basal metabolic rate (BMR) or resting energy expenditure (REE)
- thermic effect of food
- effect of physical activity (exercise)
- thermoregulation
what % contribution do each of the energy expenditure components make up?
BMR is highest (~60%)
Thermic effect of food is low (~10%)
effect of exercise (~30%)
thermoregulation is (~10% or-10%)
