The action of liraglutide is a great example of these motivations at work!

Liraglutide is a GLP-1 receptor agonist...in other words, it activates the same receptors as GLP-1.  GLP-1 is a classic satiety hormone, because it's stimulated by the digestion and absorption of nutrients.  ("GLP-1 secretion by ileal L cells is dependent on the presence of nutrients in the lumen of the small intestine.")  

Therefore, we would expect the result of taking liraglutide to simulate, at least in part, the biochemical state of already having eaten food.  That is, in fact, the case: you're probably up on all this, but my other readers can learn more about the effects of GLP-1 here.  

The interesting questions are, of course, "What caused my hunger motivations to get out of alignment, and can they be brought back into alignment?"  It's not as simple as "you have a genetic GLP-1 deficiency", because no one starts their life with Type II diabetes.  And that's why this is an interesting subject!

JS

I'm glad you find the series valuable!  I've put a lot of work into understanding the relevant literature, and I'm always glad to hear I've managed to summarize it for others in an understandable way.

JS

Always glad to see you here!  Stop by anytime.

JS

Jack Kruse

I'm not obese and never was in my 43 years. So, I have to assume the "food reward mechanism" in my brain is working ok in general. I have no problems to say no to any kind of food if I want, even after 20 hours fasting. Still, those small things once started are the most difficult to resist.
Going functional paleo made/makes me feel better (and younger) overall, that's enough for me.

I think we're onto something, because I've heard from other people that they also have trouble with grapes and other bite-size foods.  Not that it's a Major Factor In Obesity, but it's definitely a source of hedonic impact.

JS

Do you have any good starting points?  As far as I know, hedonic impact and incentive salience are directly modulated by opioid and dopamine signaling...if those are both being driven by endocannabinoids, I'd love to know more about the process.

Franco:

Very interesting!  Bite-size helps, I think, because the feeling of a new thing has hedonic impact in itself.  Taking another bite of a half-eaten donut is not as rewarding as picking up a fresh donut and taking a bite.  Does this sound right to you?

JS

You're right, I've said it before...but it's important to explain exactly why it's true.  Otherwise we can be misled into thinking that we should all be eating bland food by articles that either ignore or misinterpret the extensive existing literature on the subject of reward.

That's why your "eat some steak and eggs" strategy works: your body is saying "I need some nutrients", but it's easy for the presence of junk food to hijack that hunger.  Provide the nutrients and there's nothing to hijack.

And you're definitely correct about abstention and "out of sight, out of mind".  Again, reward and addiction have been extensively studied for a long time (though usually in the context of drugs and alcohol).  "Food reward" isn't a new concept. 

Franco:

No: your main mistake is trying to treat two values that aren't covariant as the same thing.  

If there's a constant and invariant relationship between two values, it's valid to lump them together, because you can derive one from the other.  However, in this case, there is no constant and invariant relationship between satiety, hedonic impact, and incentive salience...because satiety isn't the only thing that affects the other two.  

This is why the scientific literature defines them separately, and it's why I use them separately.

Again, you're correct that none of this is important from a "so what should I eat?" point of view.  I'm simply maintaining a sound theoretical and scientific basis for our empirical observations.

Txomin:

Future articles will absolutely turn back to empirical conclusions.  However, I find it absolutely necessary to maintain a strong theoretical basis...otherwise we just end up manufacturing dogma and starting arguments.

Example: statements like "it’s quite likely that the hypothesis in question is poorly specified" ought to be controversial...but apparently I've grounded my explanations well enough that they're not.

I'm glad you find my articles interesting and useful!  I've said it before...but the best way to thank me is to buy your Amazon stuff through my referral link (which costs you nothing) and/or to buy a copy of TGC if you haven't already.

JS

Thank you. My post is simply meant to convey that I appreciate the time and effort you are invested on the blog.