Ch. 10- Food & Mood, Craving & Addiction

• Mood and Food

  • We tend to eat food higher in carbs when mood is low
  • Foods rich in carbs increase serotonin levels (5-HT)
  • Carbs increase 5-HT synthesis, thus also improves food
  • Low brain 5-HT may cause carb craving (learned-medicine effect)
• Chocolate Craver Study

  • Sealed white chocolate, milk chocolate, placebo capsules, or nothing (Participants opened boxes at random when they craved chocolate & rated their craving intensity 90 min after consuming the chocolate)
  • Only milk choco (milk) consumption reduced choco craving
  • Caffeine is not the cause, it's the pleasure of taste/mouth feel
  • Nothing to do with ingredients b/c cocoa capsules would reduce cravings
• Chocolate Craving Explanation

  • Milk choco & choco covered sweets are more craved than dark choco, but have less caffeine
  • Onsensory (taste & smell) aspects of choco seem more important in liking & craving than the bioactive ingredients
  • Social perception that chocolate is "nice, but naughty" (indulgence)
• Reward Systems

  • Reinforcers activate "reward" systems in the brain
  • Drugs of abuse (ex: heroin) activate these systems = super stimuli
  • Recoveries activate the same systems (recovery = medicine effect)
• Brain-Regions Involved in Activating Reward System

  • ventral tegmental area (VTA)
  • nucleus accumbens- pleasure center
  • striatum- movement/motivation
  • frontal cortex- decision-making
  • Dopamine is the major neurotransmitter involved
• Evidence of Food Addiction

  • 3 groups of rats (conditions: chow only, chow + 1hr junk food; unlimited access to junk food)
  • rats learned that buzzer & light meant food shock was coming
  • Rats on unlimited junk food condition are more likely to risk food shock for the satisfaction of "food"
  • rats also had a reduced # of receptors for dopamine in the striatum (beh change + physical change mirror drug addiction in humans)
  • Endorphins-endogenous opiates- reduce pain, increases endorphins
  • Ex: runner's high
  • Naloxone & naltrexone- endorphin receptor blockers; reduce drug & palatable food consumption
• Marijuana

  • cannabinoids- endogenous cannabis-like molecule; bind CB1 receptors in brain
  • research suggests that cannabinoids interact w/ opioid & dopamine systems = food reward & motivation