Chapter 8 - Energy Balance & Body Composition

Question 1

How do you determine the amount of calories in your food?

Answer 1

1 g carb = 4 kcal
1 g fat = 9 kcal
1 g protein = 4 kcal
1 g alcohol = 7 kcal

Question 2

What’s the difference between direct & indirect calorimetry?

Answer 2

direct measure = a bomb calorimeter measures the food’s energy value (amount of heat given off)

indirect measure = the amount of oxygen consumed indirectly measures of the amount of energy released

Question 3

what is the physiological fuel value?

Answer 3

• the amount of energy that the human body derives from food
• is less than what a bomb calorimeter measures
• the body is less efficient than a calorimeter & cannot metabolize all the energy-yielding nutrients in a food completely

Question 4

what’s the difference between satiation & satiety?

Answer 4

satiation - eating & the feeling of getting full; determines how much food is consumed during a meal

satiety - feeling of fullness after a meal & inhibits eating until the next meal; determines how much time passes between meals

Question 5

overriding hunger & satiety

Answer 5

• stress eating

- cognitive influences (chocolate sounds good)

Question 6

how to sustain satiation & satiety

Answer 6

• protein is most satiating

- high-fat foods stimulate the appetite

Question 7

message central

Answer 7

hypothalamus - integrates messages about energy intake, expenditure & storage

Question 8

what factors is eating influenced by?

Answer 8

• psychological
• social
• metabolic
• physiological

Question 9

neuropeptide Y

Answer 9

a chemical messenger secreted by hypothalamus that causes carb craving, initiates eating, decreases energy expenditure & increases fat storage
- favors a positive energy balance & weight gain

Question 10

components of energy expenditure

Answer 10

• basal metabolism (basal metabolic rate = BMR)
• resting metabolic rate (RMR)
• physical activity

Question 11

basal metabolic rate = BMR

Answer 11

• approx 2/3 of energy expenditure

- supports the basic processes of life

Question 12

resting metabolic rate

Answer 12

• slightly higher than BMR

- determined when a person is lying down

Question 13

Factors affecting BMR

Answer 13

• age, height, growth, body composition
• fever, stress, environmental temp
• fasting/starvation, malnutrition
• hormones
• smoking
• caffeine
• sleep

Question 14

who does physical activity fit into energy demands

Answer 14

• most variable
• voluntary
• can have huge effect on weight control

Question 15

what is the thermic effect of food (TEF)?

Answer 15

• how much energy it takes for your body to convert food to energy
• carbs 5-10%
• fat 0-5%
• protein 20-30%
• alcohol 15-20%

Question 16

what is adaptive thermogenesis?

Answer 16

• energy expended to meet increased body challenges

- a one time event your body isn’t used to, such as, extreme cold, overfeeding, starvation, trauma

Question 17

what is Body Mass Index (BMI)? Strength? Weakness?

Answer 17

• describes relative weight for height
• does NOT take into account body composition (muscle mass)
• gives guidelines for healthy body weight

Question 18

Estimating energy requirements

Answer 18

gender
growth
age
physical activity
body composition & size: larger surface area have higher BMR

Question 19

What are risks of storing energy as visceral fat?

Answer 19

• fat that is stored around the organs of abdomen + central obesity
• this type of fat contributes to heart disease & related deaths

Question 20

Advantages & disadvantages of methods to determine body composition:

Answer 20

1. skinfold measures: limitation is that fat may be thicker under skin in one are than in another; adv - low tech
2. waist circumference: valuable indicator of fat distribution
3. waist-to-hip ratio: provides no more info than waist circumference. Women w/>.8 and men w/>.9 have a high risk of health probe
4. hydrodensitometry: weighed on land, then submerged under water. Good estimate of body fat & useful in research, but requires bulky, expensive, non portable equipment. Not always practical.
5. bioelectric impedance: low intensity current is sent through body. Is most accurate for people w/in a normal fat range; tends to overestimate fat in lean people & underestimate fat in obese people
6. air displacement plethysmography: estimates body composition by determining the amount of air displaced by person’s body.
7. dual energy s-ray absorptiometry (DEXA): 2 low dose x-rays that differentiate among lean body mass, fat tissue & bone tissue. Provides a precise measurement of total fat & its distribution.

Question 21

how does obesity impact the risk of cardiovascular disease?

Answer 21

• central obesity may raise the risk of heart attack & stroke
• high LDL
• low HDL
• high blood pressure

Question 22

how does obesity impact the risk of type 2 diabetes?

Answer 22

• a risk factor for diabetes
• obese person is 3x more likely to develop type 2 diabetes
• association between insulin resistance & obesity is strong

Question 23

how does obesity impact the risk of insulin resistance?

Answer 23

• central body fat cells appear to be larger & more insulin-resistance than lower body fat cells
• weight loss is effective in improving glucose tolerance & insulin resistance

Question 24

What are some advantages of exercise independent of total body weight?

Answer 24

regardless of body weight, fit people have a lower risk of mortality than people who are un-fit

• increased circulation
• increased mitochondria
• in creased lean muscle mass
• decrease body fat
• increase bone density
• increase coordination * balance
• enhance muscle glycogen storage
• increase O2 - CO2 exchange