Metabolic Rate and Control of Energy Intake

Question 1

Define “Energy Balance” in the human body.

Answer 1

“Energy balance” is the relationship between “energy in” (food calories taken into the body through food and drink) and “energy out” (calories being used in the body for our daily energy requirements).

Question 2

Longterm control of body weight is believed to be due to contol of energy intake; why?

Answer 2

3 Mechnisms control long term homeostatic energy balance

1. internal work and heat production (unlikely - too hot)
2. physical activity (automatic response of physical excerise in response to food unlikely)
3. regulating food intake

Question 3

What is the role of the hypothalamus in appetite control?

Answer 3

Hypothalamus contains pair of appetite centres and pair of saitety centres.

Controls food seekign behaviour and inhibition of food seeking behaviour.

Question 4

What role does insulin or glucose have in controlling energy intake?

Answer 4

A Decrease/Oncrease of particular nutrient molecule in body could induce hunger or saitety (eg glucose or insulin).

Insulin levels rise after meal. Once absorption is finished, blood glu. decreases (signals hunger?)

Leading proposal for short term regulation of timing and amount eaten in meal.

Does not explain feeling of satiety when food is still in lumen and not being utilised by cells.

Question 5

What role does leptin have in controlling energy intake?

Answer 5

Lipostatic theory states that increased fat storage in adipose tissues signals satiety. (Doesn’t account for hungry obese) therefore rather than applying the tota nuber of fat storage in adipose tissues, this theory could relate to ‘fullness’ of individual adipose tissues. Protein Leptin is released when adipocytes are full.

Binds to hypothalamic receptors. (signal satiety?)

Leptin responsible for long term matching of food intake to energy expenditure.

Question 6

What influence does psychosocial behaviour and custom play in energy intake?

Answer 6

Psychologcl and social factors that affect food consumption.

Habit, social custom

Pleasure from eating food

Stress, anxiety, depression, boredom

May overide or reinforce internal signals.