121 - Regulation of Energy Systems

Question 1

Components of daily energy expenditure
1
2
3
4

Answer 1

1) Sleeping metabolic rate + Arousal
2) Basal metabolic rate (when awake)
3) Thermic effect of food (heat released when food is digested)
4) Activity (variable amount of energy expenditure)

Question 2

Measurements of energy expenditure
1
2
3
4
5

Answer 2

1) Doubly-labelled water
2) O2 consumption
3) Heart rate-based estimation of VO2
4) Activity monitors
5) Population-based algorithms

Question 3

Doubly-labelled water

Answer 3

Label H and O in water, look at how quickly it is metabolised.
Very accurate, but difficult to do.

Question 4

How can VO2 be estimated with measuring heart rate?

Answer 4

Linear relationship between the two.

Can be inaccurate, as factors other than VO2 can alter heart rate.

Question 5

Determinants of energy expenditure 
1
2
3
4
5

Answer 5

1) Adrenaline, thyroid hormones
2) Muscle mass and oxidative capacity
3) Exercise/physical activity levels
4) Non-exercise activity thermogenesis
5) Shivering thermogenesis

Question 6

Effect of oxidative capacity on basal metabolism

Answer 6

More oxidative fibres in muscle (slow-twitch) associated with lower body mass. Might metabolise fat more effectively.

Question 7

Non-exercise activity thermogenesis

Answer 7

Fidgeting, tapping, etc during day can expend energy.

Question 8

Brown fat

Answer 8

Similar metabolic profile to muscle.
Present in low amounts in adults.
Uptakes glucose particularly in cold conditions.

Question 9

Uncoupling protein

Answer 9

Uncouples e- transport chain with mitochondrial ATPase, making the process much more inefficient. Need to expend more energy to make the same amount of ATP, generating a lot of heat in the process.
Brown fat has high transcription levels of uncoupling protein, used by hibernating animals.

Question 10

50% of current anti-obesity drugs target what?

Answer 10

CNS

Question 11

Examples of hormones that inhibit hunger (short-term)

Answer 11

CCK, GLP-1, PYY (short-term)

Question 12

Examples of hormones that inhibit hunger (long-term)

Answer 12

Leptin

Question 13

Leptin and regulation of body mass

Answer 13

Released by adipose tissue.

As adiposity increases, leptin levels increase, which reduces drive to eat.

Question 14

Effect of genetic leptin deficiency

Answer 14

Increase in adiposity.

Question 15

Why can’t obesity be treated with leptin?

Answer 15

Leptin insensitivity arises

Question 16

Example of biological factors affecting body weight

Answer 16

If monozygotic twins overfed, increase in weight fairly uniformly

Question 17

Example of an inhibitor of fat absorption

Answer 17

Xenical

Question 18

Side-effect of Xenical

Answer 18

Steatorrhoea

Question 19

Effectiveness of low-carb diet

Answer 19

Found to be mildly effective, but more data needed

Question 20

Things associated with successful weight loss
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2
3
4
5

Answer 20

1) Low calorie, low-fat diet with minimal variation
2) Eating breakfast every day
3) Frequent self monitoring
4) Regular exercise ~1 hr/day
5) Limiting TV viewing