Archive for June, 2012

NPR: Your Self-Control Can Be Depleted

What Your Brain Looks Like When You Lose Self-Control

June 22, 2012

[The following is a conversation with a researcher who has proved what I’ve always known to be true–there is a limit to my willpower.] 
 
IRA FLATOW, HOST:

Ever wonder why you worked so hard to avoid the lasagna at dinner only to give in to your craving for not one but two helpings of cake for dessert? Well, new research may hold some answers to this vexing question. A new study in the Journal of Consumer Psychology confirms what we’ve been – what we’ve known for some time, and that is each of us has an internal reservoir of self-control. We have a reservoir of self-control that it depletes. Every time we resist a temptation, we use a little bit of it up.

But for the first time, researchers have taken pictures of the brain to show what was happening when a person exerts and then loses self-control. Dr. William Hedgcock was a co-author of the study. He is a neuroscientist and assistant professor of marketing at the University of Iowa. He joins us from Denver. Welcome to SCIENCE FRIDAY.

DR. WILLIAM HEDGCOCK: Oh, thanks for having me.

FLATOW: Well, first, let me back up a bit because I think it would be surprising to most people to learn that we actually have a reservoir of self-control.

HEDGCOCK: Sure. So this is a theory called regulatory resource depletion. And like you said, when people exert self-control, what we see is people have a hard time exerting self-control later, so this idea of one resource may be, you know, not intuitive. But I think most of us have had this sort of experience where you exert self-control at one point and then end up succumbing to temptation later.

FLATOW: Mm-hmm. And where is that center of self-control?

HEDGCOCK: Well, what we’re finding is that the center seems to be the dorsolateral prefrontal cortex, so it’s an area that’s sort of near the temple and underneath the temple of your head.

FLATOW: Hmm. And how do we know that that’s where it is?

HEDGCOCK: Well, so we ran an fMRI study where we had subjects come into the scanner. They first exerted self-control, and we saw them having activation in areas like the dorsolateral prefrontal cortex and the anterior cingulate cortex. And this is what, you know, we would have expected. Then we had them exert self-control later on a subsequent task, and we saw less activity in this dorsolateral prefrontal cortex area.

FLATOW: So it had been depleted in – some of their self control was gone.

HEDGCOCK: Yeah. So we saw behaviorally that they had less self-control, and that seemed to be correlated with the fact they had less activity in that area.

FLATOW: Now, is the reservoir a reservoir of chemicals? Is it a reservoir of neurons? What exactly is the reservoir?

HEDGCOCK: So we don’t really know that yet. We do know that there’s less activity in that area. It seems unlikely that it’s a neurotransmitter, for instance, but we would need some follow-up studies to find out exactly why is it less active there.

FLATOW: Mm-hmm. And what kind of test do you do when you test people for their self-control? Do you put pie in front of them and say, you can only have one bite or what?

HEDGCOCK: Well, that certainly – some people do that. So we’ll put people in front of brownies or something and then see later, would they like to choose brownies versus a healthy snack or – also, we test them on things like, will they perform well on a cognitive task. But in the scanner, we couldn’t do that. It’s difficult to, you know, put a pie next to a person in the scanner.

(LAUGHTER)

HEDGCOCK: So what we did was something a little bit more sterile than that. We had them look at a fixation point on a screen, and we flash words underneath the fixation. And the words would move around and – but they’re very close to the fixation. We told subjects to ignore them and definitely not read them, but this was difficult or, for the most part, impossible for subjects to do. So it required self-control on their part to not read the words.

FLATOW: Don’t think of pink elephants.

HEDGCOCK: Yeah. Well, so that’s another version of – or another way to manipulate self-control. You could have them not think about elephants, which is difficult to do once we mention it to you.

FLATOW: Right. 1-800-989-8255. Talking with Dr. William Hedgcock about exerting self-control. And so can you actually tell at the moment by looking at the scan when, uh-oh, they’ve lost their self-control?

HEDGCOCK: Well, what we saw was sort of a gradual depletion over time. We didn’t see a particular timeframe. And by the way, our subjects sometimes were able to exert self-control later. It’s not like they completely lost it. They were just less able. They just occasionally would succumb to temptation more frequently than when they were not depleted.

Does Being a Healthy Weight Really Have to Be Like Having a Part-time Job?

If it does, I’m screwed.  I won’t do it, at least not for long. 

Recently, I’ve had a discussion going with some readers about whether or not being vegan is enough to ensure a healthy weight for the long term.  A couple of ideas have emerged from our discussion and warrant a little thought.

#1.  Not all vegan foods are healthy.

Absolutely.  Oddly enough, potato chips, PayDay bars, Coke and french fries are all vegan.  But, eat a serving of those bad boys more than a couple times a month and prepare to kiss your healthy weight goodbye.  It is for just this reason that I must clarify what I mean when I say “vegan.”  Vegan is a short cut for saying a “plant-based, whole food diet.”  It’s made up of food from plants in an un-processed state.  I don’t mean raw, just not shot full of chemicals that will cause it to have the shelf life of a nuclear warhead.

#2.  You can have too much of a good thing.

The thought here is that if you eat too much food, even healthy food, even vegan food, you will still gain or fail to lose unwanted weight.  True, there’s definitely no denying that.  (After all, cows, hippos, and rhinos are vegan–not exactly slim and sexy.)  However, have you ever looked at the caloric and nutritional content of beans, spinach, barley, strawberries, etc.?  You are liable to get a serious case of the trots from all that fiber before you get a chance to over indulge yourself.  I’m not saying that you can’t eat too much plant-based, whole food.  I’m just saying that you’ll have to try really hard.

#3.  No matter what you’re eating, you’ll still have to count calories.

I’m going to go out on a limb here and give my personal, yet well-informed opinion without citing any particular research.  (I know that such research exists, I just don’t feel like interrupting my typing groove by looking for it.  Check out anything by Dr. Neil Barnard.  He’s pretty much the premiere authority on all things nutrition.)  But, it makes sense to me that my body knows what to do with natural food.  It knows what to keep and what to discard.  When I’m eating natural, whole food, I get full and satisfied.  I get plenty of fiber to keep things moving along at a healthy pace.  I get plenty of nutrients to keep cells fed and regenerating.  My body does not have to treat the food I’m eating like toxic waste.  I don’t over work my liver, and therefore it is able to convert food to energy more efficiently.  

Call me crazy, but I have to assume that my body is as capable of taking care of itself as every wild animal’s running around.  (When was the last time you saw a fat squirrel.)  But, our consumption-crazed culture has thwarted our natural instincts and undermined our bodies’ regulatory capacities (thus, there are plenty of fat domestic animals–you know, animals fed by humans).  When we get out of our own way and feed ourselves the food we actually need to eat, our bodies will behave.

#4.  Not all vegans are naturally thin.

I assume that we’re talking about whole-food vegans and not potato-chip vegans otherwise this would be a ridiculous thing to discuss.  But I agree, not all vegans are thin.  Some are more curvy, not fat, just curvy.  Some seem to carry a few more pounds than others.  Some are a little stocky.  Some aren’t very defined.   Some are shaped liked apples.  Some are shaped like pears.  No shit.  In case you’ve forgotten biology class, no two humans are exactly alike.  The shape your body assumes as it grows, matures, and ages will be different than mine.  Not necessarily better or worse, but different.  If you’re deciding the merits of healthy eating based on whether or not people who eat healthy all look like movie stars prepare to be disappointed.  Some of us didn’t win the genetic lottery. 

My opinion about healthy weight has changed as I’ve gotten older and observed my grandparents.  My grandmother was about 5’4″ (she’s shrunk a little as she approaches 90), and she always fought her weight.  She was never fat, but only because she was always vigilant.  She hovered around 140-150.  If her weight crept up to 160, it wouldn’t stay long.  She’d cut out desserts and second-helpings and dive into whatever exercise was the latest craze until she was back into her size 12’s.  As she’s aged, she’s gotten smaller and smaller.  Now, at 89, she has to work to keep weight on.  I look at her healthy weight when she was 60 and it was about 20 pounds more than she wanted.  But, I think that she was just the right size for her stage in life.  Her body held on to a little extra and as she’s aged, it’s had a little extra to spare.  She’s avoided being frail and sickly.  She could get normal seasonal viruses and not turn into a walking corpse.  She still has round cheeks that make her face look cheerful.  (I thank God for genes that hold onto a few extra pounds.  I plan to save them for later when I’m old and I really need them.)  Some one could have looked at my grandmother and decided that her healthy way of eating wasn’t really all that great because she wasn’t all that thin.  They would have been wrong.  There is more to health than the number on the scale.

Warning: Low Carb Diet Could Be Hazardous to Your Heart

“Low-Carb” Diets Increase Heart Disease Risk

June 13, 2012

Low-carbohydrate diets can lead to weight gain and heightened risk of heart disease, according to a new study in Sweden. As part of an effort to reduce heart disease risk in the 1980s, more than 140,000 individuals were encouraged to decrease their fat intake. They did so, and their cholesterol levels fell—for a while. However, in the early 2000s, the low-carbohydrate diet fad led many of these individuals to forgo healthful carbohydrates and eat fattier foods instead. The results were higher cholesterol levels and overall increased heart disease risk.

Johansson I, Nilsson L, Stegmayr B, Boman K, Hallmans G, Winkvist A. Associations among 25-year trends in diet, cholesterol and BMI from 140,000 observations in men and women in Northern Sweden. Nutr J. 2012;11:40. E-pub ahead of print.

Another Myth Debunked: Soy and Breast Cancer

Study Says Soy Prevents Breast Cancer Recurrence

By Rashida Harmon | June 27, 2012

New research suggests that breast cancer survivors who consume more soy are more likely to keep the disease at bay.

A new report published in the July edition of American Journal of Clinical Nutrition suggests that soy products help prevent the recurrence of breast cancer in previously diagnosed women. The paper analyzed previous studies measuring the impact of soy on breast-cancer survivors, examining the results of more than 9,500 Chinese and American women. Upon reviewing those studies, researchers found that women who consumed the most soy products were 25 percent less likely to experience the return of the disease. Earlier this week, The New York TimesWell blog debunked the notion that soy products increase the risk of breast cancer—a myth based on the fact that soy contains chemicals that mimic the behavior of estrogen, a hormone that fuels many instances of breast cancer.

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