Food Reward: a Dominant Factor in Obesity, Part VII

Now that I've explained the importance of food reward to obesity, and you're tired of reading about it, it's time to share my ideas on how to prevent and perhaps reverse fat gain.  First, I want to point out that although food reward is important, it's not the only factor.  Heritable factors (genetics and epigenetics), developmental factors (uterine environment, childhood diet), lifestyle factors (exercise, sleep, stress) and dietary factors besides reward also play a role.  That's why I called this series "a dominant factor in obesity", rather than "the dominant factor in obesity".
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Drug Cessation and Weight Gain

Commenter "mem", who has been practicing healthcare for 30+ years, made an interesting remark that I think is relevant to this discussion:

Recovering substance dependent people often put on lots of weight and it is not uncommon for them to become obese or morbidly obese.

This relates to the question that commenter "Gunther Gatherer" and I have been pondering in the comments: can stimulating reward pathways through non-food stimuli influence body fatness?  

It's clear that smoking cigarettes, taking cocaine and certain other pleasure drugs suppress appetite and can prevent weight gain.  These drugs all activate dopamine-dependent reward centers, which is why they're addictive.  Cocaine in particular directly inhibits dopamine clearance from the synapse (neuron-neuron junction), increasing its availability for signaling.
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Food Reward: a Dominant Factor in Obesity, Part VI

Reward Centers can Modify the Body Fat Setpoint

Dopamine is a neurotransmitter (chemical that signals between neurons) that is a central mediator of reward and motivation in the brain.  It has been known for decades that dopamine injections into the brain suppress food intake, and that this is due primarily to its action in the hypothalamus, which is the main region that regulates body fatness (1).  Dopamine-producing neurons from reward centers contact neurons in the hypothalamus that regulate body fatness (2).  I recently came across a paper by a researcher named Dr. Hanno Pijl, from Leiden University in the Netherlands (3).  The paper is a nice overview of the evidence linking dopamine signaling with body fatness via its effects on the hypothalamus, and I recommend it to any scientists out there who want to read more about the concept.
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