Regulation of Body Weight and Food Intake

Question 1

Energy Balance or Homeostasis

Answer 1

Food & Caloric Beverage intake = Activity + digestion + BMR

Question 2

Potential mechanisms to adapt to the environment

Answer 2

1 .Genetics

2. Increased Energy Expenditure (REE, TEF, Activity)
3. Reduced intake/appetite
4. Changes in substrate metabolism

Question 3

Evidence of a set-point

Answer 3

Rats fed a chow diet and then either calorie restricted or overfed. They all come back to a baseline

Question 4

Energy Balance Regulation

Answer 4

Physiologic or Homeostatic Mechanisms:

• Short-Term Signals = meal related
• Long-Term Signals = adiposity-related

Non-homeostatic Mechanisms:

• Reward and motivation
• Cognitive/Executive decisions
• Environmental Cues
• Social context

Question 5

Catabolic vs. Anabolic pathways

Answer 5

Anabolic = eat more
Catabolic = stop eating

Question 6

Hypothalamus - Hunger center and satiety center

Answer 6

Lateral Nucleus - if you erode this, the rat stops eating; hunger center

Ventromedial nucleus - If you erode this, they can’t stop eating; this is the satiety center

Question 7

Leptin

Answer 7

Hormone signal associated with stimulating catabolic pathways and inhibiting anabolic pathways

Question 8

NPY

Answer 8

Anabolic

• increase food intake
• decrease energy expenditure

Release AgRP (agouti related peptide) to inhibit the catabolic pathway

Question 9

POMC

Answer 9

Catabolic

• decrease food intake
• increase energy expenditure

Question 10

Meal to meal regulation hormones

Answer 10

Ghrelin and PYY

Ghrelin - from stomach (anabolic, stimulate apetite; highest before you eat - hunger hormone)
PYY- from distal ileum (catabolic, rise after a meal, satiety hormones)

Question 11

People who are obese prone have high levels of ____ but have the same amount of hunger

Answer 11

Leptin

Are they leptin resistant?

Question 12

Do obese people have more ghrelin or PYY?

Answer 12

No. PYY is about the same and underfed people have more ghrelin

Question 13

Problems with our biologic or homeostatic regulation of food intake

Answer 13

• Maybe designed to protect during undernutrition

- Maybe resistance to signals like leptin

Question 14

Non-homeostatic regulation of energy intake

Answer 14

Internal inputs:

• Reward mechanisms
• Cravings
• Thinking about food
• Restraint
• Learned behaviors
• Attention

External inputs:

• Environmental cues (sight, smell, taste)
• Availability/Portions
• Social context
• Time cues

Question 15

What parts of the brains light up with food?

Answer 15

• Attention
• Reward
• Motivation
• Memory

Obese prone people have persistent activity in these areas