4.5 Appetite Regulation and Nutritional Balance

Question 1

What are the three fundamental components of total daily energy expenditure, and their approx. proportions?

Answer 1

• 70% resting energy expenditure
• 20% Activity-induced
• 10% Diet induced (energy of digestion)

Question 2

What are Huberman’s two types of Activity-Induced energy expenditure?

Answer 2

1. EAT: Exercise activity thermogenesis
2. NEAT: non-exercise activity thermogenesis

Question 3

Resting energy expenditure vs basal metabolic rate

Answer 3

• REE: energy requried for vital organ function in resting state
• Basal: REE as individual wakens in the morning (lowest)

Question 4

Why does diet affect daily energy expenditure?

Answer 4

Because eating protein requires more energy than eating carbohydrates and fats.

Question 5

List a whole bunch of factors that affect someone’s daily energy expenditure

Answer 5

• Age
• Gender
• Disease
• Weight
• Genetics
• Body composition
• Sleep
• Hormones
• Diet

Question 6

How does basal metabolic rate change with gender/age?

Answer 6

Gender: usually higher in men
Age: Declines w/ age; highest young, stable 20-40, declines in old age as body shuts down

Question 7

How does the PALs plus scale tell you how to maintain your weight

Answer 7

It gives you a multiple of your BMR to consume each day based on activity level (e.g. “very active” men should consume 2.3x)

Question 8

List the hypothalamic areas involved in appetite regulation

Answer 8

• Arcuate nucleus
• Ventro/dorsomedial nuclei
• Paraventricular nucleus
• Lateral hypothalamic nucleus

Question 9

What are the two neuronal populations of the Arcuate nucleus that regulate hunger? Which reduces/increases food intake?

Answer 9

POMC/CART: Reduces (too much in the cart; too expensive)

NPY/AgRP: Increase (It’s entpy, get a grip)

Question 10

Biochemically, how to POMC/CART neurons decrease hunger?

Answer 10

• POMC is a precursor for many peptides, incl. alpha melanocyte stimulating hormone.
• Alpha MSH bings to melanocortin receptor 3/4 (MCR3/MCR4)
• This reduces hunger

Question 11

Biochemically, how do NPY/AgRP neurons increase hunger

Answer 11

-NPY binds to Y1 receptors
- AgRP is an antagonist to MCR3 and MCR4 receptors (Agrip on the receptor market)

Question 12

True or false: POMC/CART and NPY/AgRP neurons are only within the arcuate hypothalamic nucleus

Answer 12

• False
• Also affected by the other nuclei that regulate hunger

Question 13

How do grehlin, leptin, and peptide tyrosine-tyrosine affect POMC/CART and NPY/AgRP neurons?

Answer 13

• Grehlin is the “hunger hormone”, so increases NPY/AgRP and decreases POMC/CART
• Leptin decreases hunger, so increases POMC/CART and decreases NPY/AgRP
• PTT inhibits NPY/AgRP

Question 14

What is the effect of glucose on the two opposing neuron systems of hunger in the hypothalamus?

Answer 14

• Inhibits NPY/AgRP
• Excites POMC/CART

Question 15

List 5 areas from which afferent information can travel to the brain regarding hunger/appetite

Answer 15

• Gallbladder
• Pancreas
• Adipose
• Liver/GI Tract
• Skeletal muscle

Question 16

What is the link between white adipose levels and leptin? Why does this make sense?

Answer 16

• The higher the white adipose, the higher the leptin
• Leptin suppresses hunger, so this acts as a negative feedback to prevent too much fat

Question 17

Outline the adipostat theory for body weight control

Answer 17

• The more/less fat, the more/less anorexigenic signals (e.g. leptin)
• This means, when we have lots of fat, we are less hungry, and vice versa
• In theory, this functions to keep weight within a certain range

Question 18

Describe two mechanisms of short-term hunger control in response to a meal

Answer 18

1. (mechanical) stretch receptors are activated, sending vagal afferents to the solitary nucleus, and out to relevant brain centres
2. (neuroendocrine) when nutrients bind to receptors in the GI tract, hormones such as GLP-1 are produced, either activating vagal afferents or travelling to the CNS via the bloodstream

Question 19

True or false: GI satiety signalling is constant throughout the day, leading to the classic 3-meal system

Answer 19

• False
• Varies w/ circadian rhythms