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Why Are We Hungry? Part I: What Is Hunger? Liking Vs. Wanting, Satiation Vs. Satiety

(This is a multi-part series: click here for the index.)

Caution: contains SCIENCE!

It is the 21st century. We have telephones that fit in a watch pocket, we can sequence the genetic code of life itself, and we can sift the accumulated knowledge of centuries in fractions of a second using Internet search engines. Yet we still don’t understand enough about human biochemistry to create a pill that stops us from eating without causing heart valve defects or uncontrollable diarrhea.

Diet pill’s icky side effects keep users honest, msnbc.com, 7/6/2007

“I’ve pooped my pants 3 times today, and sorry to get descriptive but it even leaked onto the couch at one point!”

“Ya know how when you start moving around in the morning ya pass a little gas. Well, I did and then went into the bathroom and to my horror I had an orange river of grease running down my leg.”

Do Diet Drugs Work?, The Telegraph, 4 May 2009

“I’ve done it. I figured out the secret behind the Alli pills. It’s fear…It’s amazing how the thought of suffering faecal incontinence can create rock solid will-power.

Clearly I’m in the wrong business: writing life-changing books and articles about how to stay fit and healthy is far less profitable than selling drugs that make people crap their pants.

Meanwhile, in the absence of the magical anti-hunger pill, everyone seems to have their own concept of how to defeat hunger—and thousands of diet books published every year claim that we are simply deficient in everything from acai berry extract to “resistant starch” to the urine of pregnant women. Obviously this is all baloney, because we’re fatter and sicker than ever…

…so let’s back up a few steps and ask ourselves a simple question: “Why are we hungry?”

To answer this, we need an answer to an even simpler question:

“What is hunger?”

Disassembling Hunger and Appetite

To most dieters, hunger is a crafty, insidious demon whispering sweet nothings in our ears.

"Pringles are delicious, and you can stop eating them any time you want."

Yet much of the published research, and most of the popular discourse, simply dismisses hunger as an annoying inconvenience—an atavistic, mildly embarrassing instinct that we must rise above in order to maintain our health.

This is completely untrue. Hunger is a normal and necessary human drive, and it serves a very important function: to cause us to find and ingest the nutrients we need to survive. Yet to understand hunger, we must break it down into its components, because:

Hunger is not a singular motivation: it is the interaction of several different clinically measurable, provably distinct mental and physical processes.

Until we understand this, we are doomed to perpetual confusion over our own motivations and desires—let alone others’ writings and recommendations on how to successfully deal with them.

I’ve addressed this subject before, in my very popular article Why Snack Food Is Addictive, which (among other things) explains the concept of “food reward”. What I’m doing here is creating a theoretical framework that allows us to go even farther—by understanding the concept of hunger.

Components of Hunger: Liking Vs. Wanting

We know that liking something and wanting something are not the same thing. I like prime rib, but I don’t want any right now, because I just ate.

Miraculously, the scientific literature often uses helpful and descriptive English words when describing components of hunger. “Liking” and “wanting” are part of the official scientific lexicon: “liking” is a measurement of the pleasure we experience upon eating, i.e. palatability, and “wanting” is a measurement of the relative motivation to acquire and ingest a food.

It turns out that “liking” and “wanting” produce specific patterns of activity in the human brain!

Pharmacology Biochemistry and Behavior
Volume 97, Issue 1, November 2010, Pages 34-46
Hedonic and motivational roles of opioids in food reward: Implications for overeating disorders
Susana Peciña and Kyle S. Smith

Food reward can be driven by separable mechanisms of hedonic impact (food ‘liking’) and incentive motivation (food ‘wanting’). Brain mu-opioid systems contribute crucially to both forms of food reward. Yet, opioid signals for food ‘liking’ and ‘wanting’ diverge in anatomical substrates, in pathways connecting these sites, and in the firing profiles of single neurons.

Brain Research Volume 1350, 2 September 2010, Pages 43-64
The tempted brain eats: Pleasure and desire circuits in obesity and eating disorders
Kent C. Berridge, Chao-Yi Ho, Jocelyn M. Richard and Alexandra G. DiFeliceantonio

“Liking” mechanisms include hedonic circuits that connect together cubic-millimeter hotspots in forebrain limbic structures such as nucleus accumbens and ventral pallidum (where opioid/endocannabinoid/orexin signals can amplify sensory pleasure). “Wanting” mechanisms include larger opioid networks in nucleus accumbens, striatum, and amygdala that extend beyond the hedonic hotspots, as well as mesolimbic dopamine systems, and corticolimbic glutamate signals that interact with those systems.

As we’d expect, “liking” tends to stay more stable over time, whereas “wanting” tends to change dynamically, being a measure of one’s desires at that moment:

Physiology & Behavior Volume 90, Issue 1, 30 January 2007, Pages 36-42
Is it possible to dissociate ‘liking’ and ‘wanting’ for foods in humans? A novel experimental procedure
Graham Finlayson, Neil King and John E. Blundell

Findings indicate a state (hungry–satiated)-dependent, partial dissociation between ‘liking’ and ‘wanting’ for generic food categories. In the hungry state, participants ‘wanted’ high-fat savoury > low-fat savoury with no corresponding difference in ‘liking’, and ‘liked’ high-fat sweet > low-fat sweet but did not differ in ‘wanting’ for these foods. In the satiated state, participants ‘liked’, but did not ‘want’, high-fat savoury > low-fat savoury, and ‘wanted’ but did not ‘like’ low-fat sweet > high-fat sweet. More differences in ‘liking’ and ‘wanting’ were observed when hungry than when satiated.

This would indeed seem to be the common-sense result, but it’s important to understand that liking vs. wanting are not just theoretical constructs: they are distinct biochemical processes.

These motivations don’t just apply to food: any experience we “like” is capable of producing a “want” for more. I discuss this at length in Part VIII.

Components of Hunger: Satiation Vs. Satiety

We also know that the factors which make us stop eating (satiation) are different than the factors that cause us to feel hungry or not hungry (satiety). If all I have available to eat is cotton candy, I’ll soon be satiated, with no desire to eat more—but I won’t experience satiety, because I’ll still be hungry for real food.

Like the terms “liking” and “wanting”, “satiation” and “satiety” have specific meanings in the scientific literature, though according to the dictionary they are synonyms.

Interestingly, French distinguishes them in the same way scientists do: “rassasiement” = satiation, “satiété” = satiety.

Also like the terms “liking” and “wanting”, “satiation” and “satiety” are distinct and reproducible drives:

Nutrition Bulletin Volume 34, Issue 2, pages 126–173, June 2009
Satiation, satiety and their effects on eating behaviour
B. Benelam

Satiation and satiety are controlled by a cascade of factors that begin when a food or drink is consumed and continues as it enters the gastrointestinal tract and is digested and absorbed. Signals about the ingestion of energy feed into specific areas of the brain that are involved in the regulation of energy intake, in response to the sensory and cognitive perceptions of the food or drink consumed, and distension of the stomach. These signals are integrated by the brain, and satiation is stimulated. When nutrients reach the intestine and are absorbed, a number of hormonal signals that are again integrated in the brain to induce satiety are released.

Physiol Behav. 1999 Jun;66(4):681-8.
Palatability affects satiation but not satiety
De Graaf C, De Jong LS, Lambers AC.

The results showed that the ad lib intakes of the less pleasant and unpleasant soups were about 65 and 40% of the intake of the pleasant soup. Subjects ingested about 20% more soup when the subjects had to wait for the test meal about 90 min, compared to the 15 min IMI condition. The availability of other foods had no effect on the effect of pleasantness on ad lib intake. There was also no effect of the pleasantness on subsequent satiety: hunger ratings and test meal intake were similar after the three standardized soups. One conclusion is that pleasantness of foods has an effect on satiation but not on subsequent satiety.

This is another common-sense result: we might eat less of unpalatable foods, but having eaten less, we’re more hungry afterward. And once again, we find that the motivation to stop eating (satiation) is a distinct biochemical process from the satiety (or lack thereof) we feel later on.

Conclusion

Hunger is the interaction of several different clinically measurable, provably distinct biochemical processes—each with its own effects on our brains and bodies. Until we understand this, we are doomed to confusion: fragmentary understanding and incomplete solutions that address only one component of hunger while ignoring the others.

Fortunately, we don’t have to understand the biochemical cascades involved in liking, wanting, satiation, and satiety—because no one does. (These are “active research areas”, which means “we’re still trying to figure all this stuff out”.) Simply understanding these drives on a conceptual level—and why they were selected for in our evolution as humans—can help us navigate the dangerous shoals of dietary advice.

I’ll explore some of these questions in more detail in the upcoming weeks.

Live in freedom, live in beauty.

JS

Continue to Part II, “Hunger Is the Product Of Multiple Perceptions And Motivations, Sometimes Conflicting.”


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50 comments

Permalink: Why Are We Hungry? Part I: What Is Hunger? Liking Vs. Wanting, Satiation Vs. Satiety
  • It is really useful to split these two, satiation and satiety, in order to really perfect the balance of paleo meals. Food for thought. Good one, thanks.

  • Jan

    I’ve noticed that I’m no longer afraid of being hungry, because I know if I eat a meal that is high in fat, moderate in protein and fairly low in unrefined carbohydrates I’m far less likely overeat, nor will I be hungry again in an hour or two.

    I’ve also noticed something else lately. My 16-year-old son is naturally thin and muscular. He is also pretty disinterested in food. Oh, he likes it (well, some of it), and understands what is good for him and what isn’t, but he only eats when he’s hungry and always stops when he’s full – he rarely eats everything on his plate and when he does he NEVER goes back for seconds, even when it’s something he really, really likes.

    These two things have had me thinking a lot lately about the whole “food reward” thing, especially since I’m an avid cook (and have been overweight my entire life). Now I get to wonder how his physiology differs from mine. In he meantime, I am attempting to mimic his eating habits. A paleo diet certainly helps.

  • Edje Noh

    Aah, I see, satiation is achieved by simply filling up the stomach, whereas satiety is achieved by providing the body with quality nutrients and fuel that burns slow and steady for a longer time. That’s why we should focus on getting the most nutrient and energy dense food, like mostly meats, fish, egg and veggies and a couple of other foods thrown in (healthy high-fat alternatives, fruits, nuts, starchy veg).

  • eddie watts

    yay for another update!
    i look on your blog daily because, as i’ve found with other blogs, often the comments include information i did not know previously.

    someone in the comments on another update said something about a day a week for consuming alcohol and i meant to look up on it but now cannot find that day! looks like that is what i’ll be doing today :D

  • Gluttonous babies an

    […] I’m about to publish this, I get the latest post from J.Stanton on satiation vs satiety. Looks like toddlers understand this concept much better than some […]

  • lynn

    Being Insulin resistant…I was hungry constantly…even 5 minutes after I ate a large meal. I never had a full feeling or a feeling that I was satisfied. I complained about it to my husband wondering what the heck was wrong with me. I could not possibly be hungry but I had strong cravings or urges to eat.
    After learning from Gary Taubes that insulin is a fat storage hormone and that if insulin was in my blood stream my body would/could not use my fat for fuel,I began to research. Eating whole foods, high in fat and protein has changed all that. Now I eat only when I am hungry and that is not very often. Often times I start to eat, take a few bites and want no more. What a relief.

  • Paul:

    Absolutely.  This theoretical framework lays the foundation for many important insights, some of which I'll bring up in subsequent articles.

    Jan:

    Satiation vs. satiety, and liking vs. wanting, are keys to understanding what “food reward” really means — and how it can and cannot be manipulated.  I'll get to that in the future.

    Edje Noh:

    There's more to satiation than just filling up the stomach, but you're basically correct on satiety.

    eddie:

    Thank you!  I think the alcohol idea is from Martin at leangains.com.

    lynn:

    Insulin crosses the blood-brain barrier and plays a role in satiety.  And as you found out, it's very easy to be satiated but not sated.

    JS

  • Lee

    I thought I’d pipe in and thank you for this article. I’m recouping from a severe enteritis (infection of the Ileum), if my spelling is right! It was a very discouraging month – the first week of which I lost 14 lbs. which I could hardly afford! People feared for my life – so did I! I’m back on paleo now, after a necessary carb binge since that was all my body could tolerate – still need to gain weight back – have hernia repair surgery on Monday – I’m 64 -I thought I’d say that for this past 1/2 year being on Paleo, I never experienced hunger! During my convalescence eating carbs and sugar and dairy – my hunger came back! Now it’s gone again – “right” food – the proteins and fats, make a huge difference in “hunger knowledge” as well as inflammation and energy smarts! Thanks for this article!

  • Timothy

    @Eddie

    The alcohol comment thread is here. Better than that, though, the Leangains article that I attempted to summarize is here.

    @Everyone

    Satiation vs. satiety is an important distinction and one that I only began to notice after eating paleo. For most of my life, I never experienced satiety, so I would eat to the point of satiation and beyond on other foods (thanks to gluten, at one point my belly grew larger than that of my 8-months-pregnant wife). Only after I learned to eat real food exclusively did I find out what it felt like to be sated and not even thinking about food.

    Consider pica, a disorder of eating non-food items like hair, dirt, or even sofa stuffing. Sufferers experience desperate “wanting” to eat things that they don’t really “like”. In many cases sufferers are found to be nutritionally deficient in some way, and this is thought to be the underlying cause. Pregnancy can also provoke this behavior, probably because gestation demands a certain nutritional flexibility from the mother.

    It seems to me that overeating is simply a form of pica: to the list of non-food items, we can add grains, vegetable oils, trans fats and all the modern food substitutes. But unlike eating dirt, which at least has some minerals and probiotics, eating fake foods will actually worsen nutritional deficiency. Indeed, pica might be considered the most widespread disorder in English-speaking countries, afflicting two-thirds of the population or more.

    Here’s to achieving satiety through complete nutrition, so that we can stop thinking about food all the time and focus on more rewarding activities, like mountain biking or smashing things with a sledgehammer.

  • Sean

    This series is going to be totally awesome. Keep up the good work JS.

  • eddie watts

    timothy: thanks for that, i spent all day yesterday trawling the comments section on here and had not found it yet!
    got a party coming up so will be sticking to the proposed plan here and maybe make use of it in future too

  • Asclepius

    Looking forwards to the series!

  • Kat Eden

    I like your mention of prime rib as something you would not eat when full, even though you like it. I think that’s what good food comes down to – it tastes great when hungry, but you would never binge on it out of boredom or stress! 2 kilos of broccoli sure wouldn’t go down easy, anyway!

  • Lee:

    Congratulations on getting well, and I'm glad you find this helpful.  Stick around, as there's plenty more to say about these issues.

    Timothy:

    It is absolutely true that satiation is not the same thing as satiety.  I'll be exploring this in the next article.  And I love your concept of referring to overeating as a form of pica: I'll definitely be addressing things like overeating, binge eating, and other disordered eating issues as the series progresses.

    Sean, Asclepius:

    Thanks!  Everyone thinks they've found the key to solving obesity, and there are a lot of claims being made (even in the paleosphere), but the empirical evidence shows that we haven't yet done so.  My aim is to deliver a theoretical framework that we can use to analyze dietary strategies, so we can figure out which are more likely to work in the real world.  

    Kat:

    Exactly.  The details of these motivations, and how they produce the results they do, come next.

    JS

  • Insulin doesn't

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    […] Why Are We Hungry? Part I: What Is Hunger? Liking Vs. Wanting, Satiation Vs. Satiety Hunger Is The Product Of Multiple Perceptions And Motivations, Sometimes Conflicting Restrained Eating: Willpower and Why Diets Fail (Why Are We Hungry? Part III) I agree with one of the commenter's on the last of this series that managing cortisol levels is a major factor in losing weight. I believe we all suffer too much stress and chronic inflammation results and eating comfort foods exacerbates the problem. Changing to coconut oil and increasing my fat intake helped me turn my hunger signals off and enabled calorie reduction, intermittent fasting which is something different from the Will power needed for calorie restriction which I'm not very good at. […]

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  • Jen - Personal Train

    I also think it’s important to get clarity about the differences. But although this makes it easier to understand what hunger is and why most of us are “hungry” almost all the time, it is still hard to overcome lifelong habits to be able to make a transition.

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  • Jen:

    Absolutely.  But once we're off the dime, we can make smart choices that leave us less hungry and more satisfied.

    JS

  • Diane

    ” it is still hard to overcome lifelong habits to be able to make a transition”

    I have only been eating this way for a week. I didn’t eat terribly poorly before, just not specifically high fat and low carb. I had reached a point where my constant hunger was so unquenchable I was willing to try anything. So I decided to try high fat low carb.

    I’ve felt strange all week. This afternnon I was sitting in the sun, it was after lunch. For the 5th day in a row I didn’t eat any lunch and didn’t want any lunch. I was suddenly aware that my mind had nothing to do. No hunger to think about, no foreplanning for how I was going to get food if I got hungry. No preoccupation with food in any way. Nothing. I felt sort of lost. What am I supposed to think about?

    I suppose my constant hunger has given me an eating disorder of sorts because I feel like an addict who lost the stimulous for the drug but has nothing to take its place. Has anyone written about this? Maybe this is branching too far into psychology to be a topic for the paleo folks, but it seems like an interesting topic.

  • Diane:

    No, you're not alone.

    I hear this from a lot of people…they spend most of their time thinking about food, getting or preparing food, in a state of “food coma”, or being hungry for food. It's very liberating when you realize that food no longer runs your life…but suddenly you find yourself at loose ends.

    Now what?

    There's very likely to be a list of things you've always wanted to do, but never did because you didn't have time.  Well, now you do!  So it might be time to step back and do a short evaluation: make a list over the next few days, and then decide which of those long-deferred goals and dreams you could pursue with your new-found time and energy.

    Hope this helps!  Keep us posted.

    JS

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    […] leaves me as satiated as the aforementioned large meal of muscle meat does. J. Stanton wrote an interesting series of articles regarding hunger, satiety and satiation. Reply With Quote   + Reply to […]

  • Out of My Inbox: Vit

    […] a different note, I wanted to ask you guys if you had read any of the stuff from gnolls.org.  (http://www.gnolls.org/2304/why-are-we-hungry-part-1-what-is-hunger-liking-vs-wanting-satiation-vs-sa…) Very intriguing stuff.  In the series on hunger, satiety, satiation, etc. in particular he […]

  • […] my bone stock. This diet has done for Kevin what whole foods and being able to feel my own hungers, which came from reading about the difference between sating and satiating, have done for me. He was like me, also a “Clean Plate Club” member, and now has become […]

  • […] by @lex Whole Health Source: The Carbohydrate Hypothesis of Obesity: a Critical Examination Why Are We Hungry? Part I: What Is Hunger? Liking Vs. Wanting, Satiation Vs. Satiety - GNOLL… Reply With […]

  • […] filter: burning fat is healthier. You should eat until your satiety signalling tells you to stop. Why Are We Hungry? Part I: What Is Hunger? Liking Vs. Wanting, Satiation Vs. Satiety - GNOLL… Reply With […]

  • […] What I have found surprising is not only the resistance to the idea of Food Reward but a seeming difficulty on the part of many to grasp what the idea is really about. And then there are those like my friend J. Stanton, who think an exhaustive, precise set of ideas and concepts needs to be defined and differentiated in order to avoid fog and confusion. He put up a comment as well, and also has a multi-part series on his blog, Gnolls.org: Why Are We Hungry? […]

  • […] more thinking on satiety/satiation – why do those words mean different things?? gg english. All 5 parts of this essay are quite […]

  • […] Why Do We Ever Stop Eating? Series: (1,2,3,4,5,6,7) […]

  • […] “stop” is also known as “satiation.” J. Stanton’s educational series on hunger and its satisfaction was a revelation for me, beginning with its vocabulary lesson in Part I. Not only were the […]

  • […] than a massive character flaw possessed universally by the fatties. It was a great complement to his series of posts on hunger (which are excellent to read). JS is, ahem, an unusual personality with a brainpower that makes the […]

  • […] fat dairy, vegetables, potatoes, rice,  fruit – it will not be long before you find you are feeling full and well-nourished for longer periods of the day.  As your body re-adjusts to a more plentiful […]

  • […] My thoughts here are a summarization of an excellent series of articles by J Stanton over at Gnolls Credo. It’s a bit technical, and I highly recommend you read it. Start here -http://www.gnolls.org/2304/why-are-we-hungry-part-1-what-is-hunger-liking-vs-wanting-satiation-vs-sa… […]

  • […] Victorian England. I think the gutsense guy was hinting at these things in his never ending series. Why Are We Hungry? Part I: What Is Hunger? Liking Vs. Wanting, Satiation Vs. Satiety - GNOLL… http://www.nytimes.com/2013/02/24/ma…junk-food.html How the Mid-Victorians Worked, Ate and Died […]

  • […] Ultramethabolism and Blood Sugar Solution Gnoll's Blogs on Hunger, Why and Hows (the best ever) Why Are We Hungry? Part I: What Is Hunger? Liking Vs. Wanting, Satiation Vs. Satiety - GNOLL… Art DeVince's book (New Evolution Diet IIRC) Honorable mention goes to the Wheat Belly for its […]

  • […] of this, if you’re prepared to deal with some very heavy-duty science content, please peruse this series of essays on the topic.  The short-hand version is that foods typically included in the (mis-named) […]

  • […] de apresentar à comunidade em julho ( ie. julho de 2012) [nesta série de artigos, começando por este. Referências também estão disponibilizadas em minha bibliografia. -JS] Algumas notas […]

  • […] metabolismo, saciedade e satisfação foi proposta (e fundamentada através de estudos) no artigo Why Are We Hungry. Se não tiver uma outra indicação, o fundamento do que eu afirmei provavelmente está […]

  • […] live on dates and that'll be eating primal? And here, for you to peruse and learn some things: Why Are We Hungry? Part I: What Is Hunger? Liking Vs. Wanting, Satiation Vs. Satiety There Is No Such Thing As A “Calorie” (To Your Body) Reply With […]

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