Myth or Fact: The Human Body Craves Foods That Have Nutrients It Currently is Short On

Rick A. asks: Is it true that your body craves foods that have things in it your body currently needs?

pregnant-woman-eatingHave you ever gotten up in the middle of the night and absolutely had to have cheesecake? Ever had your pregnant spouse beg you to get her pickles and cheese to go with a peanut butter and banana sandwich? Food cravings are one thing  almost every human has experienced. One of the most common theories as to why this is the case is that humans crave food that contains nutrients our bodies are short on.

Due to the complexity of how the human body regulates hunger and the potential for individuals to have abnormalities in those mechanisms, so far science has been unable to absolutely prove why we get specific cravings at specific times. That being said, while science hasn’t been able to prove the reason for certain cravings, it has been able to disprove certain theories as to the cause.  So to answer your specific question, numerous studies have shown food cravings have nothing to do with nutrient levels within your body (except for rare cases, like a disorder known as Pica, where the body craves dirt or clay in response to low levels of iron or zinc. Since no one I know has ever craved dirt at 2am, I will focus on the average person and leave Pica to the Bonus Facts below).

So if it’s not that your body is looking for certain nutrients, why do we crave odd, specific things sometimes?  The current most accepted theory as to why we crave what we do is that humans crave foods as a result of a complex web of psychological, social and cultural factors that can be powerfully motivated by environmental cues. Sounds like a bit of a cop-out answer, I know.  But let’s look at some specific examples to try to make it more clear.

Take for example that American women list chocolate as the #1 food most craved. (Incidentally, Japanese women listed sushi as their number 1.)  50% of US women say their chocolate cravings are the strongest at the outset of their period. If this was caused by nutritional deficiencies, you would assume those cravings would drop off after menopause or in the short term once the specific nutrient intake was sufficient. A 2009 survey found this wasn’t the case. So why the craving for chocolate during a period?  The more likely cause of this craving is thought to be “feel-good” neurotransmitters in the brain, like serotonin, that are released after eating sweets and carbohydrates. While I’m not a woman, I can only assume if I was on my period, I would want a little “feel-good” dessert to go with my main course of cramps, headaches, and feeling bloated.

This same type of thing can be seen in numerous types of cravings for specific foods. To understand why, let’s look at what things actually control normal hunger.  Normal hunger is regulated by an intricate system of hormones and neurotransmitters that play different roles in our body’s normal processes. For the most part, it’s controlled by the release of hormones from the hypothalamus in the brain and a circulating hormone released by fat cells known as leptin.

The feeling of hunger can be preceded by a few different things such as an increase in insulin causing a decrease in blood sugar. Studies have shown that a drop of around 10% in blood glucose levels will precede almost every meal. The release of a hormone known as ghrelin will also cause hunger. Stimulants known as neuropeptide Y and anandamide also make you want to snack, particularly anandamide binds to canabanoid receptors- the same ones that give you the munchies if you smoke Marijuana.

To combat the need to gorge yourself on bon-bons, the body’s main mechanism for telling you you’re full is the release of leptin. Leptin counteracts the effects of neuropeptide Y and anandamide. It also helps in the production of another appetite suppressant known as alpha-melanocyte-stimulating hormone. As you might expect from this, the absence of normal leptin levels has been shown to result in massive overeating and severe obesity. Another hormone that suppresses hunger is cholecystokinin. This also stimulates the body to digest fats and proteins.

Whether stimulating or inhibiting hunger, the overall drive for you to want to eat can be regulated in part by any one of these mechanisms. The abnormal production or inhibition of them can also result in different eating patterns.

A chemical consequence of eating different types of foods also plays a role in how much we eat. As I mentioned earlier, eating different foods can cause the release of “feel-good” neurotransmitters within the brain. The result can cause almost addiction-like behavior in the way we eat.  For instance, eating proteins will result in an amino acid called tyrosine. This helps the production of dopamine, norepinephrine and epinephrine. Dopamine is responsible for reward driven learning within the brain.

Eating carbohydrates like sugars, breads and pasta’s will trigger an increase in the production of insulin. The resulting insulin levels help clear out some amino acids within the bloodstream. What is left is an amino acid called tryptophan. This gets converted to serotonin within the brain. Serotonin helps with the feeling of well being and happiness. It’s also the neurotransmitter that some anti-depressants try to affect.

As mentioned before, pregnant women are socially seen as the biggest recipients of cravings because of “needing certain nutrients”. But rather than actually being short on specific nutrients from the food, the cause appears to be the same as the above.  Women who are pregnant have widely differing levels of hormones compared to when they aren’t pregnant. These hormones result in heightened senses of smell and taste, among other things. Differing levels of hormones that might produce the feeling of hunger aside, it’s because of these heightened senses that it is thought certain foods and odors can be more enticing or offensive.  In turn, this can aid in craving certain things, sometimes things that when they aren’t pregnant they wouldn’t ever want to eat, but while pregnant at times find to be the most delicious thing on the whole damn planet.

The ancillary evidence that cravings come from these complex hormonal and neurotransmitter mediated mechanisms, and not nutritional needs, can be found in the amount and type of cravings we get. One study in 2004 showed that groups of people who were forced to consume only a non-appetizing vanilla flavored protein drink for 5 days actually craved the same drink once they were allowed to begin eating a normal diet again. Eating high amounts of foods that stimulate our reward centers, will cause the normal processes that stimulate those same centers to decrease production in an attempt not to overload our bodies. The result is the same type of tolerance certain drug users feel. Eventually, just eating one chocolate bar doesn’t suppress your craving, and before you know it, you’ve scarfed down an entire bag of Hershey’s Kisses just to feel normal again. Ah, the hunger-fix of a chocoholic is revealed! The more of anything you eat will, in turn, make you crave that same thing even more.

So the next time you see a pregnant lady eating a pickle and cheese sandwich and washing it down with a cool glass of grapefruit juice, rest assured, it’s most likely hormones and neurotransmitters going wild within her body, and not that her body is necessarily short on any specific nutrient in those items.  If you want to curb cravings, following the postulate “everything in moderation” can be helpful.  So can exercise.  Eat right and workout- the best way to both increase your probable life span and improve your long term quality of life.  Seriously, go eat some fresh veggies and do a little cardio.  Elderly you will thank you and in a lot of cases, even present day you will relatively quickly see some benefits.

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Bonus Facts:

  • As mentioned above, there is a condition known as Pica. This disorder is characterized by the craving of non-food related materials. Just eating the object once does not mean you have Pica. To be diagnosed by your doctor as having it, you must continue the behavior for longer than a month and be at an age or maturity level where the behavior is considered inappropriate. Examples include eating paper, chalk, sand, glass, batteries and coins. As mentioned above, there are some cases in which children, malnourished individuals, and pregnant women begin to crave dirt and clay in response to low iron and zinc levels. In those cases, the craving will subside once those levels become normal again.
  • There are cases of Pica that are chronic and do not have anything to do with nutritional levels within the person. One extreme case involves a woman from Florida; Adele Edwards, who is now 32, has been eating the foam out of couches for over 21 years. In 2011, she averaged the equivalent of 3 pillows a week. She stated then, that in the previous year she had consumed approximately 7 couches! I suppose that’s one way of disposing of an old sofa.
  • 85% of men find that giving in to a food craving is satisfying. Only 57% of women say the same thing.  To tease a little bit, ladies, this survey certainly doesn’t help you with the male feeling that you are never satisfied no matter what good thing comes your way. 😉
[Pregnant Woman Eating Image via Shutterstock] Expand for References
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  • CounterSpace

    “To tease a little bit, ladies, this survey certainly doesn’t help you with the male feeling that you are never satisfied no matter what good thing comes your way. ”

    Nope, that’s not sexist at all. Considering the onslaught of the male failure to do anything other than rape, steal, host wars, and all sorts of holistic assaults on women and children I sure guess women should shut the hell up when they get one ounce of something good that comes to them. Yes, Siree, Bob! Women aren’t ever satisfied with their pittance on a planet full of dicks.

    • SpaceCounter

      So, you’re offended by a seemingly sexist comment, then proceed to make your own sexist comment toward men saying that they don’t do anything other than rape, steal, host wars, and all sorts of holistic assaults on women and children? That’s ironic.

      Is that how you believe progress is made or harmony achieved? By insults, stereotypes, and generalizations? And while you see this as a sexist comment toward women, it is just as sexist toward men. The comment makes two assumptions: 1) That [all] males feel women are “never” satisfied no matter what good things come their way, and 2) That women are “never” satisfied no matter what good things come their way.

      So, reexamine your frustration and assumptions and don’t use a comment by one person to make a gross overgeneralization of one specific gender. Realize that you’re making assumptions and sexist comments yourself in your response. And also realize that the author is probably not intending any malice with said comment. You can’t control what other people say or do, but you can control your emotions and reactions. If you want to put out a fire, don’t dump more fire onto it; use water.

  • Anonymous

    And speaking of the corrosive effects that periods have on the female mind here is CounterSpace to provide us with a practical example.

    To claim that men are only good for raping, stealing, warmongering etc displays the typical feminazi hypocrisy virtually all feminists display bar one or two notable examples (Camille Paglia springs it kind)

    Hypocrites, whatever their sex or race, are the most perverse and hateful examples of humanity.

  • Bow

    Well said ANON…Counter certainly sounds like a lesbian man-hater.
    On a brighter note…very interesting article, thank you.

  • Jacky

    I dont like chocolate but i crave chocolate the week before my period. It helps me keep sane. As soon as my period starts the thought of chocolate makes me feel sick. That is until the week before my next period.

  • MikeP

    meh….not sold.
    Anyone who has craved protein after days of heavy work (hiking, etc) would readily disagree.

    It should be apparent that cravings for comfort food or other foods that trigger a neurotransmitter response are fundamentally different than craving something like a pickle. Studies that don’t recognize this are suspect at best.
    If you are craving something decadent, ignore it. If you are craving something nutrious, listen to it. Should be a no-brainer.

    • Mereloo

      What you are saying makes absolute sense to me. The only exception I see is when my blood sugar is low. (I’m not a diabetic, but I get brain fog, dizziness, cold sweats, etc. that have been relived by eating sugar. In other words, unconfirmed reactive hypoglycemia because I haven’t had my blood sugar tested during an episode; but my doc said that was probably the case.) This isn’t really the same as a craving, though, and can be relieved by eating sugar (and prevented by NOT eating too much sugar at once or without protein).

      I also wonder if there are still things we haven’t figured out yet as to why we crave certain things. The way I hear this often framed in lists of food myths is the way it was phrased here, that the foods you are craving have the nutrient you are lacking. Well, we know that’s not true because of severe iron deficiency and it’s association with pica. However, the same could follow for other deficiencies. A nutrient deficiency may cause you to crave a certain food; but the food you were craving still may not contain the actual nutrient you need.

      This has been bugging me, and I’ve been trying to find the answer online; but everything is either too simplified or from a lousy source! All I seem to find are articles like the one above with the fault that I already noted (even on evidence-based sites geared to the public like me) or alternative health-type sites with charts that claim certain deficiencies based on certain cravings with suggestions for alternate foods – and absolutely zero references.

      Oh, well, I’ll stick with trying to eat somewhat healthy foods most of the time. I don’t really believe in diet restrictions, and it’s served me well. When feeling slugglish, I try to eat more healthy foods, which probably does reduce the “unhealthy” foods I eat like too much refined sugar; but I never cut them out entirely. Eating intuitively (without restricting too much or going nuts), exercising, and add extra veggies as needed seems to work for me for now.

  • Johanna Kidd

    Food glorious food!

  • Anon

    Interesting summary of the current research on the mechanisms behind appetite. As for the supposefd lack of a connection between specific nutrient shortage and cravings – unconvincing at best.
    Chocolate is not a good example, as it is host to a particularly wide range of physiologically and psycologically active compounds. It actually contains anandamide, an endocannabinoid that affects the central and peripheral nervous system in too many ways to list in a comment. Reducing this whole receptor system to the ’cause of the munchies’ is almost offensively deprecative. That said, chocolate contains various other mood regulating chemicals (e.g. theobromine or phenetylamine) and there are a bunch of accounts of 1700th century women intensely craving the bitter brown stuff long before it became the sugary treat we are so familiar with today. All in all, modern science is aware of chocolate’s effects and some of the mechanisms behind it, but to assume we fully understand what exactly it does to every specific aspect of a woman’s metabolism is absurdly premature. And this is why that special little bean remains scientifically exciting.
    Closer to the issue at hand – metabolism is extremely tricky and complex. Nobody completely gets it – Yet. And in this case the question discussed was whether or not certain (mild) specific nutrient shortages can create a specific craving, not how sugar makes one happy or how pathological nutrient deficency changes the metabolism. If (as suggested in the bonus facts) mineral deficiency can cause a craving for something as nusual as dirt, whycould not a mild shortage of the same make you crave, say, spinach? Anecdotal evidence seems to suggest it. If there is any study out on day-to-day nutrient level changes and accompanying cravings, I’d be more than happy to read it and perhaps be convinced that cravings are just psychological hokus pokus. Even the aforementioned protein-drink-cravers might have just come home from a run when their bodies demanded the bland shake. Having experienced these strange desires for certain foods and due to a lack of concrete evidince, I think this one still needs some more research before it can be discarded as ‘almost certainly’ nothing more than a psychological coping mechanism of some sort or a temporary change in taste perception.
    Thanks for an informative and thought-provoking post, though.

  • MarcoC

    I rarely eat meat and I never actually crave hamburgers. I choose to buy more expensive cuts of meat when I have a craving for it.
    All in all, I’ll eat a burger every couple of months (mostly because my wife really likes in-n-out burgers) and I eat filet mignon or equally premium cuts maybe once a month at the most.

    However, when I am in a hospital as a patient (something that 10 years ago was unfortunately a frequent event) I end up craving, to the point of obsession, any hamburger, even the McDonald ones that I usually wouldn’t feed to my cat.

    I honestly don’t know why, but after a couple of days in the hospital I become obsessed with Hamburgers. Could be because of the awful food or because I know is not something I can eat at the time.
    My wife knew that as I was getting discharged she had to stop at any burger joint to get my fix. After that was done I would go back to disliking burgers again.

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  • TallKatie

    We have a few pet ducks, which are let out of their pen every day to go forage in the field. At night, we lure the females (and the male follows) back into their pen by supplying them egg shells from chickens. They always gobble a few of these up because they crave the calcium to make their own eggs, which they lay one a day.

    When we used feed that had calcium added to it in the form of oyster shell, they wouldn’t come back at night and had to be rounded up.

    I would say this is indicative but not sure proof of a strong craving for calcium.