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Hedonic Impact (“Liking”), Incentive Salience (“Wanting”), and “Food Reward”: Why Are We Hungry? Part VI

Caution: contains SCIENCE!

Now we enter the heretofore-murky waters of liking, wanting, and “food reward”.

(Part VI of a series. Go back to Part I, Part II, Part III, Part IV, or Part V—or go on to Part VII.)

Summary: The Story Thus Far

In previous installments, we’ve established the following:

  • Hunger is not a singular motivation: it is the interaction of several different clinically measurable, provably distinct mental and physical processes.
  • In a properly functioning human animal, likes and wants coincide; satiation is an accurate predictor of satiety; and the combination of hunger signals (likes and wants) and satisfaction signals (satiation and satiety) results in energy and nutrient balance at a healthy weight and body composition.
  • Restrained eating requires the exercise of willpower to override likes, wants, and the lack of satiation or satiety; the exercise of willpower uses energy and causes stress; and stress makes you eat more. Therefore, a successful diet must minimize the role of willpower.
  • A lack of satiety will leave us hungry no matter what else we do to compensate. We fail to achieve satiety by not ingesting (or not absorbing) the energy and/or nutrients our body requires, and by an inability to retrieve the energy and/or nutrients our bodies have stored due to mitochondrial dysfunction.
  • Satiation is an estimate of future satiety based on sensory input. As with satiety, we fail to achieve it by not satisfying our nutritional needs. We can also bypass satiation by decreasing sensory exposure to our foods. Some common enablers are eating quickly, eating while distracted or on the run, and eating calorie-dense packaged and prepared foods.

A Disclaimer

I’ve put off writing these next few articles because they’re likely to cause some controversy, which I don’t enjoy. My objective with the articles I write here at gnolls.org is to organize, distill, and summarize the bewildering variety of nutritional information into succinct, helpful articles, to share them with my readers, and to improve them as new information comes to my attention.

(An aside: I thank you, my readers, for continuing to provide references, intriguing leads, and constructive criticism. Please continue to do so.)

Please note that I have no horse in any of the current races: I am neither selling diet books nor defending a career-building hypothesis, and my current series of articles started long before the AHS and any still-simmering disputes.

Finally, and most importantly, I am not proposing any new theories of hunger or obesity. The current literature is both comprehensive and, I believe, more than adequate to explain and understand observed phenomena.

That being said: let’s get started!

Endless Arguments Are Often A Sign Of Murky Definitions

When, after innumerable posts and presentations on the subject, we see very smart people unable to articulate exactly what is meant by fundamental concepts like “palatability”, it’s quite likely that the hypothesis in question is poorly specified.

Therefore, I will briefly summarize the current state of scientific knowledge, as I understand it, on the subject of hunger and reward.

Defining Our Terms: “Liking” = Hedonic Impact, “Wanting” = Incentive Salience

Though the terms “liking” and “wanting” seem reasonably self-explanatory, we must be careful when using them in the scientific sense.

When we speak of “liking” something, we’re consciously predicting our future reactions. (“I like eggs.”) However, in the scientific literature, “liking” refers only to our actual reactions of pleasure, both conscious and unconscious—the hedonic impact of an experience.

Similarly, when we speak of “wanting”, we’re consciously predicting our future likelihood of seeking out an experience. But again, in the scientific literature, “wanting” refers only to our actual motivation to do so—the incentive salience of an experience.

Curr Opin Pharmacol. 2009 Feb;9(1):65-73. Epub 2009 Jan 21.
Dissecting components of reward: ‘liking’, ‘wanting’, and learning.
Berridge KC, Robinson TE, Aldridge JW.
[Note: free full text]

In recent years significant progress has been made delineating the psychological components of reward and their underlying neural mechanisms. Here we briefly highlight findings on three dissociable psychological components of reward: ‘liking’ (hedonic impact), ‘wanting’ (incentive salience), and learning (predictive associations and cognitions).

The concept of “palatability” can be understood as the hedonic reward of food:

For most people a ‘reward’ is something desired because it produces a conscious experience of pleasure — and thus the term may be used to refer to the psychological and neurobiological events that produce subjective pleasure. But evidence suggests that subjective pleasure is but one component of reward, and that rewards may influence behavior even in the absence of being consciously aware of them. Indeed, introspection can actually sometimes lead to confusion about the extent to which rewards are liked, whereas immediate reactions may be more accurate [1]. In the extreme, even unconscious or implicit ‘liking’ reactions to hedonic stimuli can be measured in behavior or physiology without conscious feelings of pleasure (e.g. after a subliminally brief display of a happy facial expression or a very low dose of intravenous cocaine) [2,3].
-Ibid.

And when most of us think of “food reward”, we are thinking purely of “wanting”—specifically “incentive salience”:

By ‘wanting’, we mean incentive salience, a type of incentive motivation that promotes approach toward and consumption of rewards, and which has distinct psychological and neurobiological features. For example, incentive salience is distinguishable from more cognitive forms of desire meant by the ordinary word, wanting, that involve declarative goals or explicit expectations of future outcomes, and which are largely mediated by cortical circuits [34–37].

By comparison, incentive salience is mediated by more subcortically weighted neural systems that include mesolimbic dopamine projections, does not require elaborate cognitive expectations and is focused more directly on reward-related stimuli [34,35,38]. In cases such as addiction, involving incentive-sensitization, the difference between incentive salience and more cognitive desires can sometimes lead to what could be called irrational ‘wanting’: that is, a ‘want’ for what is not cognitively wanted, caused by excessive incentive salience [39•,40•,41]. [emphasis mine]
-Ibid.

That explains quite a bit right there, doesn’t it?

I’d love to quote more of Berridge et.al.—but as the full text is available for free, I’ll just recommend that you read it if you’re interested in digging into the details.

It should now be clear that “food reward” has three distinct components which we must distinguish and define if we hope to understand it:

  • The hedonic impact of eating food: its palatability.
  • Incentive salience: the drive to consume more food.
  • The process of learning, in which both hedonic impact and incentive salience are modified by experience.

If we fail to separate these components, we find ourselves creating tautologies. For example, it’s obviously absurd to say alcoholism is caused by “alcohol reward”—but if we distinguish the hedonic impact of alcohol from the incentive salience of alcohol, suddenly we have a handle by which to grasp the issues and make headway.

Intermission

Some Important Observations About Liking, Wanting, and Learning

Here are what I believe are some important takeaways from the literature as they apply to hunger:

  • Reward is not a concept limited to food. Common sources of reward in everyday life also include social approval from parents, friends, co-workers, and strangers; legal and illegal drugs; physical activities, such as recreational sports; successful accomplishment of tasks; and media consumption, including television and the Internet. Anything we “like”—anything with hedonic impact—is capable of creating and reinforcing a “want” for more—incentive salience.
        In fact, much of the literature studies drug reward (legal and illegal). These are easier cases to study, since the human body has no nutritional requirement for nicotine, alcohol, or cocaine, and reward is not tied up with other motivations.
  • Taste is not the only determinant of hedonic impact. The circumstances surrounding consumption, such as social approval, are also powerful determinants…and they don’t even have to be associated with consumption!
        For example, beer is generally an acquired taste: most of us instinctively dislike its bitterness, and only ‘develop a taste’ for beer as we associate beer drinking with intoxication and positive social interactions. Note the universal context of beer commercials: beer = fun times with friends. Also note that advertising can drive consumption, despite having no association with the actual action of consumption.
        Another example: many Muslims and Jews are repulsed by even the thought of pork purely due to social context, despite having no intrinsic inability to ingest or digest it.
  • Incentive salience (“wanting”) is not an intrinsic property of food, or anything else. Unlike our instinctive aversion to spiders, humans have no instinctual knowledge of Pringles, Twizzlers, or Cinnabons. Incentive salience is a learned property.
  • Therefore, incentive salience (“wanting”) is not a static property. It is created and reinforced by the hedonic impact (“liking”) of food consumption itself, by the positive experiences of satiation and satiety that consumption of nutritious food can produce, and by its associations with other rewarding factors and experiences (as enumerated above).
  • We must distinguish experiences that modify hedonic impact (“liking”) or incentive salience (“wanting”) from incentive salience itself. For instance, the fact that the satiety response can modify incentive salience does not make satiety part of the reward response.
        It’s even easier to understand this error when we understand that social context affects hedonic impact: it’s clearly silly to call social relationships part of “food reward”. This error has been a major source of confusion in the discussion so far.

Conclusion

In order to understand the role of “food reward” in hunger, we must define and distinguish its constituent motivations:

  • The hedonic impact of eating food: its palatability.
  • Incentive salience: the drive to consume more food.
  • The process of learning, in which both hedonic impact and incentive salience are modified by experience.

Further, we must understand that reward is not limited to food, is neither static nor an intrinsic property of the food itself, and is modified by many experiences besides its taste during the act of consumption—most of which are not themselves reward pathways.

We’ll start exploring these motivations and interactions—and how they fail—in Part VII. Click here to keep reading!

Live in freedom, live in beauty.

JS

(Part VI of a series. Go back to Part I, Part II, Part III, Part IV, or Part V—or go on to Part VII.)


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36 comments

Permalink: Hedonic Impact (“Liking”), Incentive Salience (“Wanting”), and “Food Reward”: Why Are We Hungry? Part VI
  • “it’s obviously absurd to say alcoholism is caused by “alcohol reward”—but if we distinguish the hedonic impact of alcohol from the incentive salience of alcohol, suddenly we have a handle by which to grasp the issues and make headway.”

    Nicely put.

     

    I wonder if the various biochemical mechanisms underlying 'incentive salience' can become desensitized over time – such as we see with addicts whose dose/response relationship adapts over time?

  • Franco

    The first thorough explanation of “reward” in paleo-cycles! And even I got it – almost.

    You lost me here:
    “For instance, the fact that the satiety response can modify incentive salience does not make satiety part of the reward response.”

    If satiety does modify the drive to want more food (and it does indeed!) how can it be not part of the reward response?

  • lynn

    As long as I don’t “wake the monster” of insulin, I don’t “want” any particular food. I was just on vacation for a week with 8 in-laws who ate everything that is (was) my very favorite foods, hot freshly made apple pie, at the Apple Barn in Gatlinburg,Tenn, red wine,pasta, chocolate, and so forth. I no longer “want” any particular food. I can’t be tempted. My brain knows the “monster will wake up”. I will be constantly craving and eating those very things, not because I want them but because my insulin resistance is so powerful and my muscles will literally be starving.. I could look upon all those foods last week with apathy.
    Living in freedom for me is living with out the driving constant craving. Also living in freedom from aching knees and hips.
    I’ve been doing Paleo since Memorial Day of this year. My leptin levels are probably still not optimum. I never feel satiated. I never did before I started Paleo, lo carb, but neither do I feel hungry. There have been days when I don’t eat at all because I don’t feel the need to.
    If I do feel hungry, I know I have eaten too much protein at a previous meal and I have insulin floating around. So I eat a couple tablespoons of coconut oil, or some egg yolks and go for a long walk.
    I think I could live on a stomach tube as long as the monster did not wake up. It is liberating.

  • Asclepius:

    What seems to happen often is that hedonic impact becomes desensitized over time.  Ironically, the decrease in hedonic impact usually increases incentive salience in order to maintain a similar level of stimulation.

    Franco:

    “If satiety does modify the drive to want more food (and it does indeed!) how can it be not part of the reward response?”

    Response: “If ice on the road makes my car spin out, how can it not be part of my car?”

    And if you somehow define the ice as part of your car, you're going to have to explain how and why it's moving independently of your car…in other words, you've just made a simple problem into a bizarrely complicated and abstruse hairball.

    Another excellent reason is “because that's how it's defined in the literature”.  If you're going to use standard terms, especially if you're also citing the literature, you need to use those terms in the same way the literature uses them.

    lynn:

    Part of what I'll be talking about as this series wraps up is “What is the source of my hunger?”  In your case, it sounds like your hunger is driven primarily by a satiety malfunction…issues with energy retrieval (as I discussed in Part IV) cause you to become hungry when your blood sugar fluctuates.  This is distinct from reward malfunctions, which tend to cause problems like binge eating, and which I'll discuss further in future installments.

    JS

  • Monte

    Absolute great album. Torche is great.

  • Franco

    JS,

    and maybe that’s one of the flaws in the food reward hypothesis as proposed by the supporters.
    I thought we agree that a satieting food full of nutritions(sat. fat, protein, micro-nutritions), however rewarding it is will prevent future overeating to a great extent.
    By definitions something that modifies something else must be a part of the equation.

    And honestly, your analogy doesn’t fit very well.
    I meant this: Ice on the road makes my car spin out how can it be not influencing my driving performance(reward)?

  • Monte:

    Aren't they?  I wanted to link “Grenades,” which is my favorite song, but there's no video for it.

    Franco:

    (I wrote a long reply to your comment, whereupon my browser crashed just as I was finishing it.  I'll reconstruct as much of it as I can.)

    Since I'm having a great deal of trouble communicating these concepts to you (for which I take responsibility), I'll abandon the analogy and speak directly.  I'll use the example of the satiety response as something that affects reward but is not itself a reward motivation.

    First, the effect of a food on the satiety response is not a function of its effect on hedonic impact, or vice versa.  Foods can be rewarding but not satiating, satiating but not rewarding, both, neither, or anything in between.  (To return to the analogy for a moment, the amount of ice on the road is not a function of your driving skill, or vice versa.)  Trying to measure or explain one purely in terms of its effect on the other simply doesn't work, and neither does lumping them together.

    Second, read Berridge et.al.  The reward motivations of “hedonic impact” and “incentive salience” are defined in terms of specific biological substrates in the brain.  You can't just redefine them to include other things, like nutrient sensing in the intestine (the satiety response), in order to claim that reward drives everything.  This sort of sloppy thinking and presentation is a big part of what has made our current situation so disputatious.

    “I thought we agree that a satieting food full of nutritions(sat. fat, protein, micro-nutritions), however rewarding it is will prevent future overeating to a great extent.”

    That's because high hedonic impact (“palatability”) tends to increase the incentive salience of a food — while satiation and satiety tend to decrease its incentive salience.  If we lump all these things together and call the whole hairball “food reward”, we can't possibly make any sense of the situation, and we end up with hypotheses like “eating bland food is THE solution to the obesity problem” because we can't understand that incentive salience is a push-pull between the other factors.

    I'm getting ahead of myself here: this will be explained and discussed in depth in future installments.

    JS

  • Timothy

    I’m starting to see the path around willpower here. If hedonic impact and incentive salience can be modified by experience, then willpower fades to irrelevance. A hungry Muslim in the presence of frying bacon is not tempted, even though the incentive salience might seem overwhelming to an observer with no cultural aversion to pork.

    Likewise, I found that I stopped “wanting” Cinnabons when I learned to regard them as poisonous. If you were very hungry, and placed in a room full of fresh-baked treats that you “liked” very much, but knew that the chef had spiked them all with arsenic and cyanide, you wouldn’t “want” them at all, would you? Willpower would hardly enter into the equation.

    JS, I wonder what you considered controversial about the present essay. It seems fairly bulletproof to me.

  • Uncephalized

    “Likewise, I found that I stopped “wanting” Cinnabons when I learned to regard them as poisonous. If you were very hungry, and placed in a room full of fresh-baked treats that you “liked” very much, but knew that the chef had spiked them all with arsenic and cyanide, you wouldn’t “want” them at all, would you? Willpower would hardly enter into the equation.”

    This is exactly my strategy and it works very well for instilling an aversion to these foods. I quite agree that it makes willpower a non-issue. The interesting thing to me is that I will still have cravings for specific goodies that I personally think of as “favorites” (for instance, the frosted carrot cake at the cafe down the street from my old house), because they are in a different mental category for me than the generalized “baked goods”, which I think of as poison.

    I use this to my advantage as well. For instance, I can quite easily indulge in the occasional injera (traditional Ethiopian flatbread, if you’re not familiar with it) when I go out to eat Ethiopian food with my friends, because I file it in its own category (under “things that are OK to eat with Ethiopian food”, which by nature limits my opportunities to eat it). This does not end up making it harder for me to subsequently resist other baked goods and “birdseed” non-foods, because I don’t think of them as being the same thing, and the situations where I will eat certain types are highly contextual.

    I find it amazing that I am able to so easily “trick” myself with these little mental rules. The brain is really fascinating.

  • Daniel

    So it would seem that Big Food knows something about all this.
    Correct me if I’m wrong but if they were to intersect increased palatability, ease of access, and constant advertising, wouldn’t that create a perfect storm? It would also seem that the crap food they push (drugs) makes it impossible to ever get any food reward. So like greater palatability with a lack of food reward would spiral into a greater incentive salience. Hope I have that right.

  • Beth

    The concept of “palatability” can be understood as the hedonic reward of food

    I’m not convinced of this. Kurt Harris (in your link) for example says in effect that the hedonic reward of chocolate chip cookies is higher than that for pringles, but he had a hard time ceasing to eat the pringles while he has no trouble with the cookie.

    As a practical matter, saying that a food is “highly palatable” seems to mean animals (including humans) eat a lot of it. Saying something is hedonic implies that whatever it is pleasurable — so, in this example, one would gather that the hedonic reward of the cookie is greater than that of the pringle, yet the palatability runs the other way.

    My impression is that “palatability” is like addiction. People who are addicted to something might think they derive pleasure from it, but they really consume whatever because it has twisted their bodies so it is hard and/or painful to stop.

    Beth

  • Fmgd

    Beth

    To me, saying something is “highly palatable” is more or less the same as saying “it feels good” to eat it, which in turn doesn’t mean you eat or even crave it all the time, so it fits with the idea of “Hedonic reward”.

    Using these terms, “incentive salience”, in turn, would be the thing making him crave pringles, even though he “likes” (derives “Hedonic pleasure” from) chocolate chips better. Which, according to the view presented that the reward and the incentive affect each other but are not the only things doing so, is not illogical.

  • Timothy:

    Willpower doesn't quite fade to irrelevance — but one can certainly require less of it.  The trouble comes when you say “Well, maybe I'll have just one” about something you've done that trick with, and experiencing the hedonic impact suddenly jacks up the incentive salience which you've tricked yourself into no longer feeling.  

    I'll tackle these issues in more depth in future installments, but it's good to see people already understanding where things might go.  If I've laid proper definitional groundwork and explained the existing science correctly, my conclusions should seem obvious — even if they conflict with previous presentations of the issue.

    Uncephalized:

    The brain is indeed fascinating!  Too many people think the forebrain (“executive function”, our “rational mind”) is in charge of everything; it isn't.  It's a thin layer spread on top of a big, complicated engine of emotion and instinct.  Like I said in Part III:

    As anyone who’s tried to learn to play a musical instrument knows, our prefrontal cortex, our “rational mind”, is not fully in charge. All we have to do is put our fingers here, then here, then here…what’s so hard about that? Yet it takes endless hours of practice, because our PFC isn’t even in full control of our fingers—let alone our hunger drives.

    Daniel:

    You need to add “nutritional incompleteness so as to never produce satiation or satiety” to the list.  Prime rib is absolutely delicious…but there quickly comes a point when you say “I absolutely cannot eat any more.”  Cue my point here, which is that a can of Pringles has the same calories as a dozen hard-boiled eggs.

    Also, snack foods have huge hedonic impact…but like any drug, the reward you get from consuming more and more diminishes, while your desire for the high stays the same.  As I pointed out last year, obesity is associated with reduced striatal response to palatable food.  

    Beth:

    First, a passage I quoted earlier from Berridge et.al.

    “…evidence suggests that subjective pleasure is but one component of reward, and that rewards may influence behavior even in the absence of being consciously aware of them. Indeed, introspection can actually sometimes lead to confusion about the extent to which rewards are liked, whereas immediate reactions may be more accurate [1]. In the extreme, even unconscious or implicit ‘liking’ reactions to hedonic stimuli can be measured in behavior or physiology without conscious feelings of pleasure (e.g. after a subliminally brief display of a happy facial expression or a very low dose of intravenous cocaine)”

    So it's entirely possible for your conscious mind to think you like cookies more than Pringles, but that might not be your brain's actual reaction.

    More importantly, though, is the fact that hedonic impact and incentive salience (“wanting”) are two distinct and separable phenomena, with different biological substrates.  Clearly, to Dr. Harris, Pringles have greater incentive salience than cookies, despite his rational mind's estimate that the cookies have more hedonic impact.  

    That's why I've explained these concepts!  If we present “food reward” as a single, unitary concept, we can't possibly make any sense of this phenomenon.

    (And just as I've finished writing this, I see Fmgd has said exactly the same thing.  Good work!)

    Fmgd:

    That's exactly how I interpret the literature.  I'm glad it makes sense to you.

    JS

  • JKC

    Loved the intermission. :)

    Great series! I am always happy when I see you have a new installment. I also found defining “liking” and “wanting” very thought provoking. I am not sure I see exactly where you are going to go with this, but I look forward to finding out. :)

  • Beowulf

    “Incentive salience (“wanting”) is not an intrinsic property of food, or anything else. Unlike our instinctive aversion to spiders, humans have no instinctual knowledge of Pringles, Twizzlers, or Cinnabons. Incentive salience is a learned property.”

    I’ve had arguments with adults about what kids will and will not eat too many times, and the above quote really sums it up. Kids are not born wanting hot dogs, mac and cheese, chicken nuggets, ice cream, cookies, and french fries. The same kids raised in a different part of the world may well think snacking on bugs is quite delicious. One family I know had no television, and never makes “kid” meals. The five and seven year old are expected to eat what the adults are eating, and I’ve seen these two chow down on artichokes, stir-fry, various soups and curries, and lots of other typical “adult” foods over the years.

    There are of course individual preferences (someone may not like broccoli no matter how often it’s offered), but if you raise kids on healthy stuff they’re going to eat most of it.

  • JKC:

    Torche is great!  Like I said to Monte, I actually like Grenades better, but there's no video for it.  Here's the song.

    Beowulf:

    An excellent point!  Kids are not born wanting junk…but they're exquisitely sensitive to their parents' reactions.  They want what Mommy and Daddy like, and they're not fooled when Mommy pretends to like broccoli.  When they see the parents enjoying junk food, they learn that junk food is delicious.

    Moral: eat real food and feed your kids what you're eating.  If they don't eat it at first, they'll soon be hungry enough that they'll eat it anyway.

    JS

  • Daniel

    JS: ok yeah that’s what I was getting at. The total lack of nutrients makes it impossible for the body so say, “all right,we’re good”. As well as the addictive nature of junk food. But you have said all this before if I’m not mistaken. I do appreciate you putting it into context within this specific series. Kinda ties some things together for me. I have always found that if I’ve got some random craving or even a specific one that I’d rather not indulge, if I eat say, a steak or some eggs, the cravings subside. I think for the most part the longer you can abstain from junk food the better you are even willpower wise. I quit smoking several years ago and it took about one year before I could handle being around it without it challenging my will. Food is pretty different though; smoking you quit forever, food not so much. Another example of all this is this fat aversion bull crap. We get this pounded into our heads for like 40 years or more and I hear ppl say, “fat on my steaks makes me wanna vomit”. Seriously? If a caveman heard you say that, he would slap you. And then take your steak. And your woman. Lol sheeple.

  • Franco

    So my main mistake is not to stick to the scientific defintion of the terms, right?
    I might be thinking forward too much too but I still think it is a mistake of science then, not yours, to not include satiety. After all we know that our intestine has specific sensor-machanism (and I’m not speaking about food volume only now) to report exactly what is going on down there to the brain (where reward may or may not be influenced).

  • Franco

    “Daniel:

    You need to add “nutritional incompleteness so as to never produce satiation or satiety” to the list. “

    That’s actually what I was trying to say all along. Well….

  • Txomin

    The level of explanation is certainly keeping me interested. There is danger, however, in this gradual increase of conceptualization even if it is motivated by simplification (paradoxically). It is important, as I think you’ve pointed out, to remember that these are the makings of valid working hypotheses with which to establish the parameters of a productive discussion (in contrast with the manufacture of dogma).

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

  • Daniel:

    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

  • majkinetor

    In order to understand food reward, the best thing to do is study endo & exo cannabinoid systems. Their effect on reward is so powerful, that anything else is funny compared to it.

  • Franco

    Just one interesting (I think) observation I made yesterday evening, after I couldn’t stop eating grapes (I ate 2 pounds) after dinner despite feeling full already and thinking to myself all the time “they’re actually to sweet for my liking”: Anything sweet, even too sweet AND bite-sized (and thus effortless to eat) is high reward for me. May it be the grapes or cherries, sweet popcorn or pralines (in the past). No bigger fruits or big-sized chocolate bar triggers that. Somehow the bite-size is the key for me.

  • majkinetor:

    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

  • Franco

    I’m not sure, JS, we don’t have that kinda donut-culture here in europe but I think you’re correct about the hedonic impact of new pieces of the same thing.
    After thinking about, it works with small meatballs on a buffet too, can’t stop eating those as well (except with willpower).

  • Perfect Health Diet

    […] of obesity. JS Stanton of Gnolls.org has been doing a closely related series, here’s his Part VI which explains key concepts relating to food reward, and has links to Parts I through V. Part IV […]

  • Franco:

    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

  • Franco

    JS,

    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.

  • Jack Kruse

    Jay nice job here. Enjoyed reading it.

    Jack Kruse

  • Jack:

    Always glad to see you here!  Stop by anytime.

    JS

  • Correcty Fairy

    Thank you so much for posting this article, J.!

  • CF:

    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

  • C. Perkins

    Several people have posted on the impact of insulin levels on hunger. I’m a type 2 diabetic who, despite eating a low carb diet since my diagnosis 18 months ago (and losing 60 pounds), has struggled with overwhelming carbohydrate cravings, particularly in the evenings. However, recently I’ve started on a new medication called Liraglutide (in addition to Metformin), and amazingly the cravings are pretty much completely gone. (Liraglutide is an incretin hormone mimetic that is known to promote feelings of satiety.) It has been very surprising to me to realize how much of my over-eating was triggered by hormonal imbalances. I still know that I “like” Snickers bars, but I no longer desperately want one.

  • C. Perkins:

    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

  • […] “Hedonic impact, incentive salience and food reward” from gnolls.org This entry was posted in Workout of the Day by Todd. Bookmark the permalink. […]

  • […] links interessantes: Hedonic Impact (“Liking”), Incentive Salience (“Wanting”), and “Food Reward”: Why Are We… Food Reward: Approaching a Scientific Consensus Central opioids and consumption of sweet tastants: […]

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