Chapter 8 - Energy Balance & Body Composition Flashcards
How do you determine the amount of calories in your food?
1 g carb = 4 kcal
1 g fat = 9 kcal
1 g protein = 4 kcal
1 g alcohol = 7 kcal
What’s the difference between direct & indirect calorimetry?
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
what is the physiological fuel value?
- 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
what’s the difference between satiation & satiety?
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
overriding hunger & satiety
- stress eating
- cognitive influences (chocolate sounds good)
how to sustain satiation & satiety
- protein is most satiating
- high-fat foods stimulate the appetite
message central
hypothalamus - integrates messages about energy intake, expenditure & storage
what factors is eating influenced by?
- psychological
- social
- metabolic
- physiological
neuropeptide Y
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
components of energy expenditure
- basal metabolism (basal metabolic rate = BMR)
- resting metabolic rate (RMR)
- physical activity
basal metabolic rate = BMR
- approx 2/3 of energy expenditure
- supports the basic processes of life
resting metabolic rate
- slightly higher than BMR
- determined when a person is lying down
Factors affecting BMR
- age, height, growth, body composition
- fever, stress, environmental temp
- fasting/starvation, malnutrition
- hormones
- smoking
- caffeine
- sleep
who does physical activity fit into energy demands
- most variable
- voluntary
- can have huge effect on weight control
what is the thermic effect of food (TEF)?
- 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%
what is adaptive thermogenesis?
- energy expended to meet increased body challenges
- a one time event your body isn’t used to, such as, extreme cold, overfeeding, starvation, trauma
what is Body Mass Index (BMI)? Strength? Weakness?
- describes relative weight for height
- does NOT take into account body composition (muscle mass)
- gives guidelines for healthy body weight
Estimating energy requirements
gender growth age physical activity body composition & size: larger surface area have higher BMR
What are risks of storing energy as visceral fat?
- fat that is stored around the organs of abdomen + central obesity
- this type of fat contributes to heart disease & related deaths
Advantages & disadvantages of methods to determine body composition:
- skinfold measures: limitation is that fat may be thicker under skin in one are than in another; adv - low tech
- waist circumference: valuable indicator of fat distribution
- 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
- 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.
- 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
- air displacement plethysmography: estimates body composition by determining the amount of air displaced by person’s body.
- 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.
how does obesity impact the risk of cardiovascular disease?
- central obesity may raise the risk of heart attack & stroke
- high LDL
- low HDL
- high blood pressure
how does obesity impact the risk of type 2 diabetes?
- a risk factor for diabetes
- obese person is 3x more likely to develop type 2 diabetes
- association between insulin resistance & obesity is strong
how does obesity impact the risk of insulin resistance?
- 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
What are some advantages of exercise independent of total body weight?
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
