Week 6 readings summary

Question 1

what is TEE?

Answer 1

total energy expenditure

represents the summed daily metabolic activity of all organ systems

Question 2

what is the most variable component of TEE?

Answer 2

PA

Question 3

what is additive TEE?

Answer 3

Energy spent each day on non-PA physiological activity is fixed and doesn’t change, regardless of variation of PA

Question 4

what is constrained TEE?

Answer 4

non PA EE adapts dynamically to variation in PA to maintain TEE within some narrow physiological range

Question 5

what happens in the additive TEE model?

Answer 5

EE increases with PA in a linear dose-dependent manner. Non-PA metabolic activity (which includes basal metabolic rate) is not affected by variation in PA.

Question 6

what happens in the constrained TEE model?

Answer 6

TEE is homeostatically maintained within a narrow range. Increasing PA has a limited effect on TEE and instead leads to a reduction in non-PA metabolic activity to keep TEE near its set point

Question 7

How does natural selection favour constrained TEE?

Answer 7

For organisms with high PA during food-poor periods, an additive TEE strategy would maximize energy requirements precisely when the risk of starvation was most severe, whereas a constrained TEE strategy would reduce energy requirements and mortality risk

For organisms that work hardest when stockpiling food energy during food-rich periods, a Constrained TEE strategy would lower energy requirements and thereby maximize surplus energy gain.

A Constrained TEE also could reduce the risk of predation while foraging by reducing the amount of time needed to obtain food during high-PA periods.

Question 8

what is the evolutionary cost of a constrained TEE strategy?

Answer 8

the reduction in energy allocation to non-PA activity, particularly reproduction, during high PA periods

Question 9

why is a constrained TEE strategy beneficial?

Answer 9

A Constrained TEE strategy keeps energy requirements in check while allowing the organism to prioritize and allocate energy among various organ systems in a dynamic manner that is responsive to current conditions and maximizes lifetime reproductive fitness.

Question 10

disadvantage of additive TEE model

Answer 10

an animal will lose somatic capital (body weight) rather than increasing EE in high PA conditions to compensate for the high PA

Question 11

Conclusions of PA, TEE and body size?

Answer 11

In populations where PA and food availability are both high, developing individuals may target a higher TEE and smaller body size, reducing non-PA metabolic requirements while maintaining a higher TEE ceiling

Question 12

when do effects of increased PA diminish?

Answer 12

as the body adapts to higher levels of PA to maintain TEE

Question 13

static approach of energy balance

Answer 13

This approach states that a ‘change in energy stores = energy intake − energy expenditure’ and assumes that by simply changing either side of the energy balance equation weight is gained or lost.

Question 14

disadvantages of static approach of energy balance model?

Answer 14

doesn’t consider individual differences

doesn’t take into account increase in EE that would occur as body weight is gained

Question 15

what is a dynamic process of energy balance?

Answer 15

This means that altering one component of the energy balance equation (i.e., reducing energy intake or increasing energy expenditure) can affect numerous biological and behavioural factors on both sides of the equation in unpredictable and unintended ways

Question 16

what factors regulating and influence energy balance?

Answer 16

genetics
environment
psychological
metabolic
energy intake/expenditure

Question 17

effect of health related fitness on metabolic rate

Answer 17

The amount of PA needed to change fitness level depends on the overall energy cost of PA and the type, frequency, duration and intensity of the activity relative to body weigh

High fitness levels = high RMR

Thus, as health-related fitness increases the body becomes better at utilizing fat as a fuel compared to a sedentary individual at the same intensity of PA or exercise

Question 18

effect of PA on muscle and bone

Answer 18

If muscle mass is lost, strength and RMR will decrease, resulting in an overall reduction in total energy expenditure

Muscle mass is gained or maintained through PA and helps prevent the typical decline in RMR seen during periods of energy restriction (e.g., dieting) because muscle mass is more metabolically active than fat mass

Question 19

what happens when energy restriction alone is used to produce weight loss?

Answer 19

muscle tissue is lost

Question 20

when body weight is lose due to energy restriction alone, what happens to RMR?

Answer 20

RMR declines, causing total daily energy expenditure to drop below predicted levels based on weight loss alone

Question 21

when body weight is gained what happens to energy efficiency?

Answer 21

decreases because movement can be difficult and requires more energy

Question 22

what has a recent review of studies found evaluating exercise and weight loss in dieters?

Answer 22

only lost 1/3rd as much weight as expected due to compensatory behaviours e.g. increased hunger due to exercise

More common in women

Question 23

what does higher-intensity exercise do?

Answer 23

suppress hunger or food intake during post exercise period

Question 24

what activities suppress appetite?

Answer 24

running
skipping
high exercise interval

Question 25

what stimulates appetite?

Answer 25

swimming

walking

Question 26

How does the environment affect hunger?

Answer 26

Cold promotes

Heat blunts

Question 27

what is energy flux?

Answer 27

energy flux refers to the rate of energy conversion for either energy expenditure or transformation to storage - , energy flux represents the amount of energy moving through the body each day

Question 28

what does high flux do?

Answer 28

Maintains overall higher EE

Heightened sensitivity to appetite control

Allows for more appropriate energy intake or volume of food consumed