Welcome to the continuing diary series "Let's Read a WHEE Book Together!" This week, we're continuing with David Kessler's The End of Overeating, Chapter 7. If you're just discovering this diary series, you will find links to the previous installments at the bottom of this diary.
WHEE (Weight, Health, Eating and Exercise) is a community support diary for Kossacks who are currently or planning to start losing, gaining or maintaining their weight through diet and exercise or fitness. Any supportive comments, suggestions or positive distractions are appreciated. If you are working on your weight or fitness, please -- join us! You can also click the WHEE tag to view all diary posts.
The End of Overeating, by David Kessler, M.D.
Chapter 7: Amping Up the Neurons
Kessler opens with a discussion of neurology, and introduces the idea of neural encoding - that is, neurons that respond strongly to a single aspect or multiple aspects of a sensory stimulus. For example, some neurons will primarily respond to sweetness, others respond most strongly to fat or salt. Still others may respond to combinations of tastes or textures. Scientists can use functional Magnetic Resonance Imaging (fMRI) to create images of the neurons that fire off in response to a stimulus.
After noting that taste is the most reinforcing aspect of food (other aspects such as smell and texture enhance the eating experience), Kessler explains that the neurons that respond to the pleasurable aspects of food are part of the opioid circuitry. Opioids, a.k.a. endorphins, are natural chemicals that produce pleasure, similarly to narcotic drugs. Besides causing pleasure, opioids can reduce pain and stress - and can also enhance the pleasures of eating. That is, eating palatable foods causes pleasure and can also make food even more palatable - a positive feedback loop.
The relationship of palatable food to the opioid circuitry can be demonstrated using drugs that artificially stimulate or inhibit opioid action. For example, a lab animal fed a particular flavor of treats for an hour will favor a different flavor afterwards - but if the experimenter injects opioids directly into the animal's brain, it will continue to eat the original flavor with as much gusto as ever. On the other hand, administering opioid antagonists such as naloxone (used to treat narcotic addiction in humans) will cause lab animals to eat less of a palatable food like chocolate.
The most sensitive part of the opioid circuitry, the pleasure center of the brain, is an area about the size of the head of a pin, and found in the nucleus accumbens. This is the "hedonic hot spot."
Upcoming WHEE diaries:
September 20
Sun AM - louisev - Turtle Diary
Sun PM - ???
September 21
Mon AM - NC Dem
Mon PM - ???
September 22
Tues AM - Clio2 (Kessler, Ch. 8)
Tues PM - ???
September 23
Weds AM - Edward Spurlock
Weds PM - ???
September 24
Thurs AM - A DC Wonk -- WELCOME!
Thurs PM - ???
September 25
Fri AM - ???
Fri PM - Brimi
September 26
Sat AM - ???
Sat PM - Edward Spurlock (Kessler, Ch. 9)
If you're just discovering this series, or want to catch up on a previous installment, here are links to the story so far:
Introduction (written by me)
Chapter 1: Something Changed . . . America Gains Weight (me).
Chapter 2: Overriding the Wisdom of the Body (Clio2)
Chapter 3: Sugar, Fat, and Salt Make Us Eat More Sugar, Fat, and Salt (me)
Chapter 4: The Business of Food: Creating Highly Rewarding Stimuli (Clio2)
Chapter 5: Pushing Up Our Settling Points (me)
Chapter 6: Sugar, Fat and Salt Are Reinforcing (Clio2)