Hunger and Eating

Question 1

Ways in which digestion delivers energy

Answer 1

• Lipids (fats)
• Amino acids (used to build protein)
• Glucose (carbs & sugar)

Question 2

Primary source of energy storage

Answer 2

• Adipose (fat) tissue

Question 3

Energy Metabolism

Answer 3

• The chemical processes through which energy is used and made available for bodily functions

Question 4

Metabolism is largery controlled by the circulation of

Answer 4

• 2 key pancreatic peprides that act as hormones:
  
  • Insulin
  • Glucagon

Question 5

Insulin

Answer 5

• Use of glucose as primary energy source
• Conversion of blood glucose to glycogen & fat, and amino acids to proteins
• Storage of energy (more fat in adipose tissue, proteins in muscle, glucogen in liver and muscle)
  
  • Insulin increases the short-term use and long-term storage of glucose.
  • Insulin is used at times when glucose levels are (or are expected to be) high

Question 6

Glucagon

Answer 6

• Release of free fatty acids from adipose tissue (fat reserves) to provide energy to the body
• Gluconeogenesis: The conversion of protein to glucose to use a fuel
  
  • Glucagon withdraws energy from the body’s reserved when glucose is not available
  • Glucagon is used at times when glucose levels are low

Question 7

Phases of Energy Metabolism

Answer 7

• Changes over 3 phases that are related to the recency of food consumption
  
  • Cephalic Phase
  • Absorptive Phase
  • Fasting Phase

Question 8

Cephalic Phase

Answer 8

• Starts with sight, smell, or thought of food
• Ends with food enters bloodstream
• Insulin is part of the phase

Question 9

Absorptive Phase

Answer 9

• The period in which energy is absorbed into bloodstream
• Insulin is involved in this phase

Question 10

Fasting Phase

Answer 10

• Food is in the distant past. Immediate metablic effect of food no longer meets energy requirements.
• Energy must be extracted from reserves
• Glucagon involved in this phase to extract energy

Question 11

Two theories of hunger

Answer 11

• Set-point theory
• Postive-incentive perspective

Question 12

Set-point theory Basic Principle

Answer 12

• Hunger arises when people are experiencing an energy deficit.
• Eating replenishes energy reserves to some optimal set-point, and hunger is alleviated.
• Set-point theory is a negative feedback system

Question 13

Evaluating set-point theory: PROS

Answer 13

• Intuitive appeal
  
  • When we are hungry, we feel like we are out of energy, and that we have to replenish some reserve
• Simplicity
  
  • Set-point theory proposes a simple homeostatic model through which hunger is regulated.
  • Occam’s razor stresses parsimony. We should accept the simplest theory or model that can explain the phenomenon

Question 14

Positive Incentive Persepctive (Berridge, 2004)

Answer 14

• Humans and animals are drawn to eating for foods pleasurable quality, rather than because they are running out of immediate resources
• Based on motivational accounts of affect/emotion
• Pleasure from food
  
  • Sweet tastes produce liking responses across species (Berridge, 2004)
  • Wile bitter tastes produce aversive responses (Berridge, 2004)

Question 15

Positive-incentive theory: PROs

Answer 15

• Positive-incentive perspective suggests that hunger and cravings depend on the interaction of multiple factors that influence the positive incentive value of food:
  
  • The taste of the food
  • Your previous experience with the food
  • Sensory feedback about the amount of food in your gut
  • The presence of absence of other people in the eating context
  • Your current mood
  • Your current glucose levels, and so on…
• Does not limit hunger to one single mechanism

Question 16

Innate taste preferences

Answer 16

• Sweet and Fatty tastes
  
  • Adaptive: These foods tend to be characterisitc or high-energy, high nutrition foods
• Salty tastes
  
  • Adaptive: characteristic of sodium rich foods. Sodium regulates fuild balance, nervous system acitivity

Question 17

Innate taste aversions

Answer 17

• Bitter tastes: In nature, bitter tastes are often coincide with poisonous plants

Question 18

How do we know when we are full? - Based on the two theories reasoning

Answer 18

• Set-point hypothesis: signals about the energy content from the food eaten returns us to a pre-defined energy requirement
• Positive-incentive hypothesis: we should stop eating when food is no longer pleasureable