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Wednesday, October 10, 2007

Homeostatic Hyperphagic Obesity

Recently I had the pleasure of enjoying a 2 hr walk-'n'-talk with John Blundell (perhaps known to many of you as the ingestive behaviour "guru" from Leeds). He talked to me a lot about his research and how his group had developed a series of tools that would help distinguish "homeostatic" from "hedonistic" eating.

I must admit, that although the concepts were intuitively familiar to me, I had not thought about these issues in such clear terms.

The basic idea is as follows:

There are essentially two different kinds of eating:

1) homeostatic eating - regulated by "hunger" and "satiety"


2) hedonistic eating - regulated by "appetite" and "reward"

Let me give you examples:

When you skip breakfast, have a small salad for lunch, and then arrive home "starving" and barely make it to the refrigerator in time to polish off last night's leftover pizza, before going on to eating everything else in sight before that comfortable feeling of "fullness" (read: "satiety") sets in, then you have just experienced "homeostatic" eating - you ate because you were "starving" and rapidly eating large amounts of (junk?) food is nothing but the normal response to being hungry.

On the other hand, when you've just had a three-course lunch and return to your desk only to find that the work you left lying around is still waiting for you as a result of which you suddenly feel the urge to open the secret drawer and finish the bag of chocolates - that is "hedonistic" eating - you ate because of the "pleasure" (read: "reward") that comes from eating a bag of chocolates - this has nothing to do with hunger or energy regulation.

Why is the difference important? Well for one, we know that there are different molecules and receptors responsible for "hunger" and "satiety" than there are for "appetite" and "reward". These systems are in fact so different that the therapeutic approaches to deal with "homeostatic" vs. "hedonistic" eating are bound to be different (will save my thoughts on this for another day).

In any case, the bottom line is that we probably need to actually figure out why a given individual is "hyperphagic" (i.e. eating too much) in order to provide the proper counseling and treatment. Simply put, the solution for "homeostatic" eating may be to correct the eating pattern, thereby avoiding hunger; the solution for "hedonistic" eating may be to develop coping strategies that will help "apease" the reward system without calories - very different approaches indeed.

Well, in real-life things are of course far more complex - most people (like myself?) are probably both "homeostatic" and "hedonistic" eaters - more of one or the other depending on your day.

OK, so who said real-life has to be simple?

In any case, I can't wait to try out John Blundell's "hedonistic tool-box"!


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