28. Energy Expenditure Flashcards
Define
Non-exercise adaptive thermogenesis (NEAT)
the energy expended for everything we do that is not sleeping, eating or sports-like exercise
Define
Total daily energy expediture (TDEE)
an estimation of how many calories you burn per day when exercise is taken into account
Define
Basal metabolic rate (BMR)
the rate of energy expenditure per unit time by endothermic animals at rest
Define
Beige adipocytes
a type of adipose cell described by the ability to induce these cells to produce heat and increase energy expenditure
Define
Brown adipocytes
typically found in large amounts in newborns and some hibernating animals and is important as a source of energy. These contain numerous and very distinct lipid droplets as well as large amounts of mitochondria
Define
White adipocytes
rounded cells that contain a single large fat droplet that occupies over 90% of the cell volume and the mitochondria and nucleus are squeezed into the remaining cell volume
Define
Adaptive thermogenesis
the change in energy expenditure following acute and/or long-term overfeeding and underfeeding
Definition
the energy expended for everything we do that is not sleeping, eating or sports-like exercise
Non-exercise adaptive thermogenesis (NEAT)
Definition
an estimation of how many calories you burn per day when exercise is taken into account
Total daily energy expediture (TDEE)
Definition
the rate of energy expenditure per unit time by endothermic animals at rest
Basal metabolic rate (BMR)
Definition
a type of adipose cell described by the ability to induce these cells to produce heat and increase energy expenditure
Beige adipocytes
Definition
typically found in large amounts in newborns and some hibernating animals and is important as a source of energy. These contain numerous and very distinct lipid droplets as well as large amounts of mitochondria
Brown adipocytes
Definition
rounded cells that contain a single large fat droplet that occupies over 90% of the cell volume and the mitochondria and nucleus are squeezed into the remaining cell volume
White adipocytes
Definition
the change in energy expenditure following acute and/or long-term overfeeding and underfeeding
Adaptive thermogenesis
What are the three components of energy expenditure?
Adaptive thermogenesis
Physical activity
Obligatory energy expenditure
What does the physical activity component of energy expenditure included?
Exercise
Non-exercise activity thermogenesis (NEAT)
What are the characteristics of adaptive thermogenesis?
- Variable, regulated by the brain
- Responds to temperature and diet
- Occurs in brown adipocyte mitochondria, skeletal muscle and other sites
Which component of accounts for the most energy expenditure?
Obligatory energy expenditure (BMR)
~70%
What happens to BMR as we age?
It decreases
Why do men tend to have a higher BMR than women?
They have greater lean mass
True or False:
Energy expended by tissues is directly correlated with its mass
False
Examples:
Skeletal muscle makes up 50% of the body mass but 20% of energy expenditure
Heart, kidneys, liver and brain make up 6% of the body mass but 60% of energy expenditure
Which tissue receives a several fold increase in enery expenditure during exercise?
Skeletal muscle
What happens to the coronary, kidney and splanchnic energy expenditure during exercise?
Coronary: Increases
Kidney: Decreases
Splanchnic: Decreases
True or False:
Weight change in response to exercise is genetically determined
True
Determined through twin studies
How much exercise is required to promote clinically significant weight loss?
225-420 minutes per week
What are the benefits of exercise (weight loss) on metabolic health?
- Improved lipid profile (↓ triglyceride, ↑ HDL)
- Reduced fasting glucose and insulin levels
- Improved insulin sensitivity
- Reduced hepatic fat accumulation
- Reduced blood pressure
- Improved cardiac function
What does non-exercise adaptive thermogenesis include?
Walking
Talking
Fidgeting
Postural allocation
What is the biochemical cause of thermogenesis?
Uncoupling proteins in the mitochondria that produce heat
What environmental cues cause adaptive thermogenesis?
Cold temperatures
Eating
What is the difference between white and brown adipocytes?
White: One large fat store, few mitochondria. Stores energy
Brown: Few, multiple fat stores and many mitochondria. Expends energy
How is brown adipose tissue sympathetically controlled?
Cold/food is detected by the brain which triggers sympathtic neurons to release noradrenaline which is recognised by the beta adrenoceptor on the brown adipocyte, this causes increased synthesis of cAMP, causing lipolysis of fat molecules and stimulates uncoupling proteins to produce heat
True or False:
Brown fat is derived from muscle
True
Where do white and brown fat originate from?
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Why do newborns have large amounts of brown fat?
To maintain core body temp since they have no shiver reflex
What happens to brown fat volume over the lifespan?
Large amounts as a newborn but decreases when shivering reflex appears. Very low levels in childhood but dramatically increases during puberty reaching its peak during yound adulthood. Gradually decreases as we age
Is brown adipose tissue more active in men or women?
Women
How many calories does 50g of WAT store?
300-500 calories
How many calories does 50g of BAT burn per day?
100-300 cal/day
Approximately how much BAT does an adult human contain?
50-100g
Other than burn energy, what else does BAT do?
Clearance of harmful metabolites (i.e. triglycerides)
Improved insulin sensitivity (i.e. glucose disposal)
Cardioprotective (improved metabolic health and secretion of batokines)
Which uncoupling proteins are thermogeneic?
UCP 1
UCP 3
Which uncoupling protein(s) are/is found in brown fat?
UCP 1
Which uncoupling protein(s) are/is found in skeletal muscle?
UCP 2
UCP 3
Which uncoupling protein in skeletal muscle is thermogeneic?
UCP3
What tissue other than BAT is thermogeneic?
Skeletal muscle
How does calcium cycling contribute to adaptive thermogenesis?
The Ca released from the sarcoplasmic reticulum is actively pumped back in by the SERCA 1/2a to maintain calcium balance. This process consumes ATP and produces heat
What are the physical characteristics of beige adipocytes?
Multiple fat droplets
More mitochondria that WAT
Which type of fat can be turned into beige adipose tissue?
WAT
What triggers cause WAT to brown?
Cold
Beta agonism
What triggers cause beige adipose tissue to whiten?
What is thermogenesis?
The dissipation of energy through heat production
Which tissues does thermogenesis occur in?
BAT, skeletal muscle and beige cells
True or False:
Both NEAT and adaptive thermogenesis are controlled by the brain through the same network that regulates appetite
True