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Judith J. Wurtman, PhD

Judith J. Wurtman, PhD

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Cravings: Why Are Premenstrual Women Desperate for Chocolate?

Posted: 11/22/10 07:59 AM ET

I nearly fell off the treadmill the other day when I heard on TV that snapping a rubber wristband against the wrist would stop the need to eat cookies.

"I would like to see a premenstrual woman zooming in on a piece of chocolate, suddenly stop, snap the wristband and then settle for a celery stick," I muttered to myself as I resumed my running.

A craving for carbohydrates is generated by the brain, not the taste buds, and is as natural as feeling thirst when the body needs water. Thus snapping a rubber band against the wrist to stop cravings is about as effective as hitting your head against the wall when you are thirsty and trying not to drink.

The thirst and the cravings are signals from our bodies to do something. Thirst is a demand that we drink to increase our blood volume. Carbohydrate craving is a demand that we eat something sweet or starchy because the brain needs to make serotonin. However, unlike thirst, the craving for carbohydrates is often accompanied by deterioration in mood. Studies we carried out at MIT many years ago found that when people had an urge to eat carbohydrates, they were usually stressed, irritable, angry, depressed, cranky, distracted, tired or impatient, or all of the above. These moods of course, reflect a change in serotonin activity or levels.

Serotonin is made after any non-fruit carbohydrate is eaten and digested. Insulin is released and the pattern of amino acids in blood shifts to allow tryptophan to enter the brain. Tryptophan is converted to serotonin very quickly and serotonin levels increase in the brain. This discovery was made in the early 1970s.

I agree with the prohibition against eating carbohydrates that are greasy or high in fat like fried batter, chips, doughnuts or other sweet or starchy fatty foods. The brain doesn't want the fat; it wants you to eat carbohydrates. Whether you choose to eat the carbohydrate in the form of a healthy whole-grain food such as multigrain Cheerios or a high-fat, sugary food like a candy bar is another matter. All that the brain requires is that you consume about 30 grams of carbohydrate and -- this is important -- that the carbohydrate food is low in protein. Protein prevents tryptophan from getting into the brain. (Fructose, the sugar in fruit and in many sugary drinks, is the one carbohydrate that does not lead to serotonin production.)

Carbohydrates that contains large amounts of fat, such as cookies and ice cream, are digested more slowly than fat-free carbohydrates, so it takes the brain a longer time to make serotonin.
Just as we lose our thirst after drinking water, we lose our cravings after serotonin is made. And as an added benefit, those unpleasant moods we experienced along with our cravings are replaced by a decrease in stress and an increase in calmness, energy, focus and patience. Of course, if people are prevented from eating carbohydrates by wristbands, the cravings don't go away. Instead, they will seem to take on the form of an addiction. We all know that when we are terribly thirsty, all we can think about is how and when we can drink. When the brain needs to make serotonin, the cravings can become just as insistent.

And who has the worst, most insistent carbohydrate craving? Women with PMS. The saying, "I could kill for chocolate," is, one hopes, not based on reality but there are plenty of anecdotes of women braving hurricanes and blizzards to get their carbohydrates when they have PMS.

We studied the food choices of women with severe PMS who stayed in the MIT Clinical Research Center at the beginning and end of their menstrual cycle. These normal weight women increased their calorie intake by more than 1,100 calories daily when they were premenstrual -- and the calories came entirely from carbohydrates.

When we discovered that inadequate serotonin activity was behind their food cravings and their premenstrual moods, we tried treating these symptoms by giving the women a fat-free, protein-free carbohydrate beverage twice daily. We reasoned that if serotonin could be increased with a small amount of carbohydrate, then perhaps these women could feel better without resorting to drugs or herbal supplements. The carbohydrate intervention worked extremely well; not only did the women feel significantly better, they also were able to control their appetite.

When the brain wants carbohydrates to increase serotonin, neither wristbands nor will power is going to prevent someone from doing what the brain wants. Of course, the carbohydrate craver should be encouraged to choose healthy carbohydrates and remember that only 30 grams, not 30 cookies, have to be consumed.

The payoff is worth it. A lot of carbohydrate cravers are going to be much happier after their cravings are satisfied -- and their wrists won't be sore.

 

Follow Judith J. Wurtman, PhD on Twitter: www.twitter.com/stopmed_wt_gain

I nearly fell off the treadmill the other day when I heard on TV that snapping a rubber wristband against the wrist would stop the need to eat cookies. "I would like to see a premenstrual woman zoom...
I nearly fell off the treadmill the other day when I heard on TV that snapping a rubber wristband against the wrist would stop the need to eat cookies. "I would like to see a premenstrual woman zoom...
 
 
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11:18 PM on 12/16/2010
I'm with kaylayuh - salt beats chocolate every fricking time for me. I for one am sick and tired of the female chocolate stereotype. It's nice as a treat every now and then, sure, but it's not anywhere in sniffing distance of even my top ten favorite foods. Geez.
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kaylayuh
09:48 PM on 11/27/2010
I usually crave salt more than chocolate. I guess I'm an anomoly.
bichn
There ain't no rest for the wicked.
08:02 PM on 11/26/2010
Who cares why? Just give it to them.
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02:13 PM on 11/24/2010
"I agree with the prohibition against eating carbohydrates that are greasy or high in fat like fried batter, chips, doughnuts or other sweet or starchy fatty foods."
The craving is not asking for carbohydrates, it's asking for fat, a rarity in the pre-grocery store era. Carbs are usually more handy as I've never seen a beef steak in the vending machine nor in any handy form to munch on in the car after grocery shopping.
As for chocolate cravings, I've noticed mine are tightly tied to how much dairy I've been eating.
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happycat
No bio needed. My cuteness speaks for itself.
04:08 PM on 11/23/2010
When I am going through PMS, NOTHING can stop me from eating chocolate.
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eLucida
Liberate Fitzwalkerstan, defeat A.L.E.C.
08:57 AM on 11/23/2010
Interesting theory with one major flaw:

Chocolate is not pure carbohydrate.

Chocolate contains fat, trace nutrients and phytochemicals, and even a little caffeine.

Women do not crave glucose syrup (pure carbohydrate) they crave CHOCOLATE.
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eLucida
Liberate Fitzwalkerstan, defeat A.L.E.C.
09:37 AM on 11/23/2010
"Carbohydrates that contains large amounts of fat... are digested more slowly than fat-free carbohydrates, so it takes the brain a longer time to make serotonin."

Chocolate contains 20% to 55% fat

"All that the brain requires is that you consume about 30 grams of carbohydrate and -- this is important -- that the carbohydrate food is low in protein."

Chocolate contains 3% to 22% protein.

http://www.cacaoweb.net/nutrition.html

Chocolate may well have an effect on brain serotonin levels.

But theory posted here needs some work.
08:19 AM on 12/04/2010
o wow, I will definitely keep these things in mind!
http://faceturkey.com
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ThomasPaine1776
Left is right; Right is wrong
11:42 PM on 11/22/2010
Cause it Fing tastes GREAT
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morris111
fac fortia et patere
10:49 PM on 11/22/2010
All I know, is that when the dreaded PMS monster comes to my house, chocolate is the ONLY thing that calms the savage beast!
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happycat
No bio needed. My cuteness speaks for itself.
04:09 PM on 11/23/2010
Same here.
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DrP
10:41 PM on 11/22/2010
The way to stop carb cravings is to eliminate them from the diet. They are addictive; the insulin swings caused by dietary carbohydrates cause feelings of hunger and cause over-eating, the carbs can't be used by the bodies of many of us due to insulin-resistance and get stored as fat while we feel like we are starving and crave more and more. Vicious cycle.
Dietary fat on the other hand is very satisfying. It takes very little to feel full and the feeling lasts for hours. On a high-fat diet, the body turns to ketones for energy which is the preferred fuel for the brain. In otherwords, we become fat-burners...isn't that what we want?
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purenergy
05:17 AM on 11/23/2010
so are you suggesting that we no longer need to eat fruits and veggies? Only meat and fats?
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sabelmouse
my micro bio is emty
08:48 AM on 11/23/2010
this is so over.
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coldwatermd
10:33 PM on 11/22/2010
What was in the carbohydrate drink?

Alexa Fleckenstein M.D., physician, author.
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suzjazz
10:09 PM on 11/22/2010
Thankfully, I no longer have periods. When I did, I craved chocolate every month.
But what about cultures that don't have readily available chocolate? In many parts of the world, chocolate is not a part of the daily diet. What do those women crave premenstrually? I suspect that the comfort value of chocolate is more of a factor than the serotonin boost. Chocolate has not been around since the dawn of humanity. Women survived their periods for centuries without it, though they probably craved other foods.
09:46 PM on 11/22/2010
I just eat Nutella right out of the jar... Now that I think about it I need to buy more!! lol
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11:26 PM on 11/22/2010
You are my kind of girl, k.

I was stoked when they finally brought it to the U.S. when I was a kid.
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NHGranite
Killer Koala escapes diner, eats shoots & leaves
09:05 PM on 11/22/2010
Chocolate is very high in magnesium. I find myself craving chocolate when my magnesium levels are low. B6 is another needed supplement, or as my girlfriend and her daughter's called it "B itch 6"
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RhiannonRings
Childfree and loving it!
08:59 PM on 11/22/2010
I always crave Reese's Peanut Butter Cups for some reason..well, they are good!
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WoodsideCraig
Author of the blog "The Weiler Psi"
08:57 PM on 11/22/2010
Where can I get this carb only fat free, protein free drink? I crave starches and experience sudden mood swings (for the worse) when I get close to mealtime.