energy expenditure Flashcards
why is energy expenditure data needed
needed when trying to predict the energy needs of individuals and populations.
what percentage of energy expenditure is used up in each area of expenditure
60% BMR - this fluctuates from each individual and over lifespan
10% dietary and cold induced thermogenesis - e.g. when we eat food we produce heat
15-30% physical activity
how do men expend more energy than women
due to muscularity and size
what does post prandial mean
after eating
what is the basal metabolic rate (BMR)
Minimum rate of energy utilisation needed to sustain life
Energy needed to sustain life – respiration, circulation etc.
how is BMR measured
Measured in a fasted individual lying at complete mental & physical rest in a warm, dimly lit room at least 12h after the last meal.
what is resting metabolic rate (RMR) compared too BMR
If any of these conditions for BMR are not met, EE may be termed resting metabolic rate (RMR).
It is higher than BMR (approx. 1.1 x BMR) as it takes account of a degree of activation of the sympathetic nervous system.
what is sleeping metabolic rate (SMR) compared to BMR
SMR gives slightly lower values
(5-10% lower) than BMR.
what percentage of the liver contributes to the BMR percentage
27%
what percentage of the brain contributes to the BMR percentage
19%
what percentage of the muscle contributes to the BMR percentage
18%
what percentage of the kidney contributes to the BMR percentage
10%
what percentage of the heart contributes to the BMR percentage
7%
what percentage of the rest of the organs contributes to the BMR percentage
19%
what is postprandial thermogenesis (PPT)
The increase in Energy expenditure caused by ingestion of food.
E required for the digestion, absorption, transport & storage of nutrients.
Accounts for ~10% of daily Energy expenditure, but depends on food composition and its metabolic fate.
Starts within minutes of eating and rises to a maximum in ~ 3h. The effect can continue for ~15h.
what is diet induced thermogenesis (DIT)
is used to describe longer term effects of diet on Energy expenditure
what can the thermic effect of food also be referend to as
Specific dynamic effect of food
Thermogenic effect of food
Dietary thermogenesis
Diet induced thermogenesis
what does cold induced thermogenesis include
Includes both shivering and “non shivering thermogenesis”.
how does cold induced thermogenesis affect BMR
Increase in BMR when heat lost to environment is increased by cold, air movement, lack of shelter/clothing.
why is physical activity data useful in research
investigating the association between physical activity (or lack of it) and patterns of morbidity and mortality.
why is there Wide variation in the energy cost of any activity both within and between individuals
due to differences in body size, type and duration of activity, and speed with which the activity is performed.
how much of the energy expenditure does physical activity represent of a moderately active individual
15 - 30%
what are the 2 ways we can express energy costs of an activity to compensate for differences in body size
Physical activity ratio (PAR)
or
Metabolic equivalent of task (MET)
what is physical activity ratio (PAR)
PAR is an expression of the energy cost of an activity as a multiple of the individual’s BMR.
how can we calculate the Energy spent per unit time for an activity using PAR
Energy spent per unit time for an activity = BMR x PAR for that activity.
what is metabolic equivalent of a task (MET)
A practical way of expressing and comparing the intensity and EE of physical activities of people of different weight.
Expresses EE of a physical activity as a multiple of RMR (resting metabolic rate) while taking account of the individual’s weight.
(1 MET = 1 kcal kg-1 hr-1 = 4.184 kJ kg-1 hr-1 is assumed)
MET values range from 0.9 (sleeping) to 18 (running at 17.5 km/h).
what does 1 MET indicate
‘rest’
what does 3-6 METs indicate
‘moderate exercise’
what are the physical activity benefits
Sufficient, regular physical activity is beneficial for the health of the body and mind:
- Heart, skeletal muscles, bones, blood
- Immune system and nervous system
- Psychological wellbeing, self-perception and
- self-esteem, mood, sleep quality
Physical activity reduces the risk of many chronic health conditions.
Physical inactivity shortens life expectancy – responsible for 9% of premature deaths and causes direct cost to NHS of £91m per year.
Erosion of muscle and bon as grow old, but if use these muscles and bones from a young age you start from a higher point, so it takes longer for ur bones and muscles to decline.
Greater exercise pumps more blood around body with is good on cardio vascular system
Being physically active improves immune system
Risk of some cancers is impacted by ur physical activity levels
It psychologically makes u feel better as improves mood and sleep quality
how many minutes of physical activity should 1 - 5 year olds aim for
at least 180 mins a day
this can include: jump, layground, climb, skip, scoot, bike, dance, walk, etc
what do the UK physical activity guidelines suggest 5 - 18 year olds should be exercising for how many minutes
60 mins a day
incuding ex: bike, swim, play, skip, climb, workout, dance, PE, sport, etc
how many minuites of physical activity is suggested by the UK physical activity guidelines for adults and older adults
at least 150 mins a week of moderate intensity or at least 75 mins of vigorous intensity a week
ex include: swim, stares, sport, dance, cycle, run, walk
should also do activities aimed to improve balance 2 days a week
what are the UK physical activity guidelines for disabled adults
try make it a daily habit
do strength and balance activities at least 2 days a week
aim for 150 mins a week of moderate intensity activity
what are the UK physical activity guidelines for pregnant women
aim for at least 150 mins a week of moderate intensity activity
do strength training twice a week
what are the UK physical activity guidelines for women after pregnancy
aim for at least 150 mins of moderate activity a week
start pelvic floor stretches
build back up to muscle training activities twice a week
name factors influencing energy expenditure
Age
Sex
body size
lean body mass
diet
nutritional state
disease/illness
pharmacological agents
genetic differences
physical activity
climate
physiological state
psychological state
how does age influence energy expenditure
BMR (and therefore EE) ↓ from birth to old age.
In adulthood, there is a ↓ in lean body mass (FFM) and an ↑ in adipose tissue, and therefore a ↓ in BMR.
how does sex influence energy expenditure
BMR is ~10% lower in females compared with males – due largely to different body size and body compositions (FFM).
how does body size influence energy expenditure
There is a linear relationship between metabolic rate and body size.
Larger people have a higher metabolic rate: in adults, a 10kg difference accounts for ~500kJ/d difference in BMR.
Body size accounts for >50% of the variability in BMR between individuals.
Body weight also affects EE of physical activity when the activity is weight bearing. (most exercise is weight bearing - a non weight bearing one would be swimming)
how does lean body mass influence energy expenditure
Lean body mass is a good indicator of metabolic rate. Almost 20% of resting metabolism is expended by skeletal muscle.
At rest, adipose tissue has a lower
metabolic rate than lean tissue (BMR
often expressed per kg of fat free mass).
Adipose tissue will affect EE where the
physical activity involves movement of
the body.
how does diet influence energy expenditure
EE immediately after a meal will depend on the composition of the meal (thermic effect of food) – greater in response to protein than fat or Carbs.
its a shot term affect
how does nutritional state influence energy expenditure
BMR is increased by 5-10% by sustained overfeeding and normally reduced by the same amount by underfeeding.
this has a long term effect
how does disease/illness influence energy expenditure
Fevers, tumours, skin burns ↑ BMR and therefore EE.
how do pharmacological agents influence energy expenditure
Caffeine, nicotine – small ↑ in EE.
Amphetamines and experimental drugs used to treat obesity - ↑ EE.
Beta blockers – may slightly ↓ EE. Beta blockers can help reduce anxiety so can reduce EE as anxiety increases EE
how do genetic differences influence energy expenditure
BMR varies by up to 10% between subjects of the same age, sex, body weight and fat free mass. This may be due to genetic factors.
how does physical activity influence energy expenditure
Highly variable, depends on activity, intensity, duration of activity.
how does climate influence energy expenditure
Energy is expended due to the need to maintain body temperature by shivering/ perspiring.
Were less physically active when its really warm as we generate even more heat when we exercise, so it would be too hot
how does physiological state influence energy expenditure
Hormonal factors – endocrine disorders such as:
Hyperthyroidism – increases BMR
Hypothyroidism – decreases BMR
Thyroid hormones effect BMR
Higher BMR = higher EE, so lower weight
