Dopamine and Eating Disorders: Obesity

Judging by popular beliefs about obesity, we might think weight and eating, like drug use, are also controlled by dopamine, but this is only partly true.

         We have a built-in “weight thermostat.”  Our bodies store energy in the form of fat.  When our fat cells are full, they secrete the hormone “leptin” and we feel less hungry. 

         Also, when we lack nutrients, our brain secretes “orexin” to make us feel hungry.  When we eat and have plenty of circulating nutrients, the brain secretes “CRH” to make us feel full.

         However, eating results in higher levels of dopamine as well.  So the news isn’t completely clear when it comes to dopamine and obesity.

         Genetic components of weight also include sensitivity to all these signals.  We may have more or fewer receptors for the signals, or more or less sensitive receptors.

         So weight regulation is more complex than drug addiction.  We don’t “need” drugs and alcohol, so leaving them out of our lives is a more straightforward cure.  But we do need to eat, so it’s not surprising to discover that regulation of eating is complicated.   



Uh-Oh. Animals Are Getting Fat Too

A new research study shows that America’s obesity problem is not limited to humans.  Rather, our animals are getting fatter too.  Cats and dogs, research animals including primates and mice, and wild urban rats are all undergoing an increase in obesity.

         This new finding goes along with the puzzling nature of the human obesity epidemic.  Lots of magazine articles blame American obesity on super-sized MacDonald’s meals and sitting all day in front of computers and electronic games. 

         But lots of studies show that the obesity problem is not that simple.  Other factors seem to be at work.  Now, the fact that animals living near or with humans are also suffering from rising obesity points to some common environmental factor.  The study I am citing controlled animal diets and exercise, so the animals are not getting fat from being snack-happy couch potatoes

         In my last post (Dec. 28, 2010), I wrote about the possibility that the plastic ingredient BPA, an endocrine disruptor, could be causing declines in sperm counts.  This same BPA has been shown to have a significant connection with obesity, as have other pollutants.  Certain cold viruses have also been shown to be connected with obesity.

         So it seems quite possible that our environment is working right along with our lifestyles to make us and our animals fat.  When this mystery gets solved, I wonder if we’ll also understand the environmental factors that bring about autism, breast cancer, and other modern scourges.

         With all that still remains to be discovered, 2011 should be a year full of wonder.  Happy New Year!