Energy balance Flashcards
3 types of energies
- heat
- mechanical
- electrical
3 components of energy expenditure + %
- Basal metabolism (50-65%): activities that keep body functioning
- Thermic effect of food (5-10%): body’s metabolic response to food
- Physical activities (25-50%)
Factors that affect BMR. What raises BMR? What lowers it?
age, height, growth, body composition
Raises BMR: fever and stress, smoking, caffeine, hormones, more lean tissue
Lowers BMR: fasting/starvation, malnutrition, hormones, sleep
How to calculate BMR? Formula + have to be: (6). if conditions not met?
Indirect calorimetry through respiratory gas exchange. CO2/O2
Have to be: completely relaxed, reclining, awake, thermoneutral, fasted, no PA for last 12 hours
If not met: Resting Metabolic Rate
1 lb of fat = _____ kcal?
3500 kcal
454 g fat in body –> ___% is fat
87%
How much error in EER? less accurate for who?
20% –> plus or minus 10%
elderly and ethnic groups
Physical activity VS Physical activity level –> which is used in formula for EER? what are the ranges?
PA is used:
Sedentary: 1.00
Low active (30-60min): 1.11-1.12
Active (at least 60min): 1.25-1.27
Very Active (2-4h per day): 1.48-1.45
Hunger = ______ influences
Caused by (5)
Hunger definition
physiological influences
- caused by empty stomach, gastric contractions, absence of nutrients in small intestine, GI hormones, endorphins triggered by smell/sight/taste/food
- irritating feeling when energy is low
2nd step of food intake (after hunger) + what influences?
Seeking food and starting a meal
- sensory influences: thought, sight, smell, sound, taste
3rd step of food: what influences? (6)
cognitive influences
- presence of others, social stimulation, perception of hunger, favorite foods, time of day, abundance of food
Satiation = when? + what influences? + what happens
Satiation definition?
- end of meal, when food enters digestive tract
- post-ingestive influences
food in stomach triggers stretch receptors –> nutrients in small intestines elicit hormones (CCK which slows gastric emptying) - satiation = short term feeling of fullness: tells you to stop eating
Satiety: when? + what influences? + what happens?
Satiety definition
- several hours later, after nutrients enter blood
- post-absorptive influences: nutrients in blood signal brain about availability, use and storage –> as nutrients dwindle, satiety diminishes –> hunger develops
- satiety = long term feeling of fullness
Appetite control: what governs regulation of appetite/eating?
the brain
Homeostasis of hunger controlled by what?
Hypothalamus
givers hunger signal –> physiological –> gastric hormone
Reward system controlled by what?
Dopamine system:
gives feeling of pleasure –> tends to be the most powerful of the 3
Cognition controlled by what?
Prefrontal cortex and hippocampus: I know chocolate is not good –> eat apple instead
Appetite = _________ hunger –> influenced by what?
psychological hunger –> not actually in need of food
- influenced by external environment and cues (seeing and smelling cinnabon)
Leptin = ______ hormone –> tells you you’re ________
- made by _______ tissue + some produced in ________
satiety. tells you you’re full
- made by adipose tissue + some in stomach
Negative feedback loop of leptin
gain in body fatness stimulates leptin production VS loss in body fatness suppresses leptin production
High levels of leptin will (2)
- tell brain that you have plenty of fat stored
- act on hypothalamus to decrease food intake (increase satiation) + decrease body weight + increase energy expenditure
Low levels of leptin will (2)
Tell your bain fat stores are low + you need to eat
Can the body be desensitized to leptin?
Yes! leptin resistance
Ghrelin = _______ hormone –> tells you you’re ________ –> what do they do?
Hunger hormone
tells you you’re hungry
- may help prepare for food intake by increasing gastric motility and gastric acid secretion
Ghrelin regulation –> highest when and low when?
Highest before meal when hungry + return to low levels after mealtime
What gives sensation of fullness? which nutrients + other characteristics?
Fat and protein –> slow stomach emptying = feeling of fullness
- protein = most satiating macro –> thermogenic + aa role in brain
- high in fiber, in water + puffed with air
Healthy BMI? vs underweight? vs overweight vs obese?
healthy: 18.5-24.9
underweight: <18.5
overweight: 25-29.9
obese: >30
Limitations of BMI (5)
- doesn’t distinguish between body composition
- focusses on weight
- doesn’t say where fat is located
- ethnicity differences
- a lot more things influence health (exercise, diet…)
- doesn’t tell you fitness level or proportion of lean/muscle mass
Healthy body weight defined as weight that ______?
Does not increase risk of disease
Subcutaneous vs visceral fat
Subcutaneous: most evident, below skin, pear body
Visceral: central obesity, surrounding organs = higher risk of disease –> apple android
In general, women have __% more body fat than men at same BMI
12
Health problems associated with overweight/obesity (7)
T2D, dyslipidemia, hypertension, coronary heart disease, gallbladder disease, obstructive sleep apnea, certain cancers
Health problems associated with underweight (5)
undernutrition, osteoporosis, infertility, impaired immunocompetence, eating disorder
Fat cell development: hyperplasia vs hypertrophy?
Hyperplasia: grow more in number
hypertrophy: increase in size
Fat growth and fat loss schéma (4)
- fat cells increase in number (hyperplasia)
- when energy intake above expenditure: hypertrophy
- if continues: fat cells may increase in number again
- with fat loss, fat cells shrink but don’t decrease in number
Lipoprotein lipase: what does it do?
Hydrolyzes triglycerides passing in bloodstream (in adipocytes and muscle) –> put them into cells
How can Lipoprotein lipase affect people with obesity?
They might have more LPL and LPL that work more efficiently –> more difficult to lose weight
Set point theory
Body strives to achieve homeostasis –> hypothalamus makes adjustments to return to set point.
Yo-yo dieting (5)
Diet –> metabolism slows down –> end of diet –> normal eating (or more) –> weight gain –> repeat
Physical activity can _______ metabolism and ___________ –> PA + diet = stronger effect to (3)
increase metabolism and energy out
- stronger effect to lose abdominal fat + retain more muscle + regain less weight
