Body composition & Energy Expenditure

Question 1

what are the major differences in weight, fat and muscles of women and men?

Answer 1

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

Question 2

What are some general characteristics about body composition of males vs. females?

Answer 2

• 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)

Question 3

What are some factors that would affect body composition?

Answer 3

• age
• gender
• race
• heredity
• stature

Question 4

what happens to body composition from birth to age 10?

Answer 4

• 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

Question 5

after what age, weight gain is due to fat deposition?

Answer 5

after age of 25

Question 6

True or False: Fat deposition is higher in females than males?

Answer 6

True

Question 7

what are some characteristics of a healthy vs. obese body composition?

Answer 7

obese: much higher fat, less muscles, less organs, less bone (% body mass)

Question 8

what is BMI? what are the units?

Answer 8

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)

Question 9

what would be a BMI of someone who is underweight?

Answer 9

anything lower than 18.5

Question 10

what would be a BMI of someone who is overweight? obese?

Answer 10

overweight: from 25-29.9
obese: anything above 30

Question 11

what is the healthy (normal) BMI range?

Answer 11

18.5-24.9

Question 12

how does stature affect body composition?

Answer 12

taller individuals have leaner body mass than shorter ones

Question 13

how does heredity (race) affect body composition?

Answer 13

Blacks (N.America) have leaner body mass and denser bones than whites

Question 14

how does gender affect body composition?

Answer 14

exists from birth but more apparent at puberty (males have more muscle, more weight, more bone, less fat)
-drastic changes to females in menopause

Question 15

what are some methods for measuring body composition?

Answer 15

• anthropometry
• densitometry
• absorptiometry
• total body water
• total body K
• there are indirect ways of measuring fat mass & fat-free mass (lean body mass)

Question 16

How does Anthropometry work ? what assumption does it assume?

Answer 16

Estimates body composition by measuring different circumference and skin fold sites
Assumption: direct relationship between subcutaneous fat and total body fat

Question 17

what are the 5 sites usually used in Anthropometry?

Answer 17

1- back of the upper arm (triceps)
2- subscapula (man boobs)
3- suprailiac (hips?)
4- Abdomen (gut)
5- Thigh

Question 18

How does Densitometry work?

Answer 18

Based on measuring body density (specific gravity) and can be measured by dividing body weight in air by loss of weight in water

Question 19

what is body density?

Answer 19

body density= Wt of body in air/ body wt in air- body wt under water / density of water -RLV

Question 20

what are the 2 equations to calculate body fat %?

Answer 20

% 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

Question 21

How is total body water measured?

Answer 21

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.

Question 22

what is the formula used for total body water?

Answer 22

C1V1=C2V2

total body water= V2= C1V1/C2

Question 23

how is fat free mass calculated?

Answer 23

fat free mass= total body water/ 0.732

Question 24

how is body fat calculated from total body water?

Answer 24

body fat= total body weight- fat free mass

Question 25

what is a calorie?

Answer 25

the basic unit of measuring heat energy–> heat energy required to raise the temperature of 1g of water 1 degree (at 15 degree celcius)

Question 26

how many Joules is one calorie?

Answer 26

1 cal= 4.187J

Question 27

what is an oxygen bomb calorimeter?

Answer 27

instrument used to measure heat of combustion using oxygen

Question 28

what is the physiological fuel value of food?

Answer 28

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)

Question 29

what are the physiological fuel values for carbohydrates, protein and fat?

Answer 29

CHO= 4 Kcal/g
Protein= 4 Kcal/g
Fat=9 Kcal/g

Question 30

what are the components of energy expenditure?

Answer 30

total energy expenditure consists of:

1. basal metabolic rate (BMR) or resting energy expenditure (REE)
2. thermic effect of food
3. effect of physical activity (exercise)
4. thermoregulation

Question 31

what % contribution do each of the energy expenditure components make up?

Answer 31

BMR is highest (~60%)
Thermic effect of food is low (~10%)
effect of exercise (~30%)
thermoregulation is (~10% or-10%)