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posted by martyb on Saturday July 19 2014, @08:55PM   Printer-friendly
from the misleading-seeing dept.
An Anonymous Coward writes:

A deficit discovered in reward-based learning, specific to food, among women with obesity highlights the behavioral aspects of the epidemic and holds potential for combating it, according to a report published in Current Biology.

"Women with obesity were impaired at learning which cues predict food and which do not, but had no trouble learning similar associations with money," Ifat Levy, PhD, of the Yale School of Medicine, told Endocrine Today.

The impairment was markedly different in women with obesity vs. those with normal weight, and not seen in men, in an appetitive reversal paradigm conducted by Zhihao Zhang, a PhD candidate at Yale University, and colleagues, including Levy.

"Although we do not know whether this impairment is a cause for obesity or its effect, this finding provides a link between reward learning and obesity, which can now be used to further probe these questions," Levy said.

The journal article is paywalled, but an abstract is available.

 
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  • (Score: 5, Informative) by captain normal on Saturday July 19 2014, @09:54PM

    by captain normal (2205) on Saturday July 19 2014, @09:54PM (#71316)

    It might be easier to discern what the study was about by reading something with a bit more information than an a abstract. (Sometimes I wonder if some of our friends are part of the staff of these scientific publishers that charge outrageous amounts for a glimpse at some study that likely was funded by public money...end of rant.)

    http://www.sciencedaily.com/releases/2014/07/140717124840.htm [sciencedaily.com]

    http://news.yale.edu/2014/07/17/when-it-comes-food-obese-women-s-learning-impaired [yale.edu]

    http://www.latimes.com/science/la-sci-sn-food-reward-obese-women-20140717-story.html [latimes.com]

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  • (Score: 4, Insightful) by frojack on Saturday July 19 2014, @10:59PM

    by frojack (1554) on Saturday July 19 2014, @10:59PM (#71330) Journal

    Yeah, I found this more than a little obtuse, bordering on a joke submission to see if the reviewers at Current Biology were paying attention.

    Part of the problem is the phrase "cues in the environment that predict food", when food was never on the table (see what I did there?). Rather the "reward" was always just another picture, not actual money or actual snacks.

    Your links make it just a little bit more believable.

    To test the ability of normal-weight and obese men and women of acquiring and modifying cue-reward associations, the researchers presented participants with one of two colored squares followed by a reward (a picture of either money or food) or not.
    These studies showed that obese women struggled to make those predictions as accurately as normal-weight individuals or as obese men did when the reward was food, either pretzels or chocolate candies, as opposed to money.

    This suggests they were told what the reward would be ahead of time. Either a picture of food, or a picture of money, or a picture of neither (non-reward). (Any thing else would require Omniscience).

    And because it lead to errors, and therefore REDUCED the probability of (pictorial)rewards, you can't really make the claim that in real life random (or poor) choices would lead to more actual food. In fact, you could probably make the claim that this was a subconscious AVOIDANCE of food, rather than some food-picture induced learning disability.

    It leaves open the possibility that heavy women are more likely to be dieting than heavy men or skinny folks, and dieting people tend to be hungry people, and hunger tends to cloud one's thinking, especially when told food was involved.
    Food... Reward... Must... Resist....!

    Run the test again with Hooter's Girls appearing promising vague "pictorial Rewards" and I bet all the guys become distracted just as easily.

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    • (Score: 3, Interesting) by Reziac on Sunday July 20 2014, @02:16AM

      by Reziac (2489) on Sunday July 20 2014, @02:16AM (#71382) Homepage

      I've known obese women who didn't seem able to discern what a normal portion was. Instead of eating a normal portion, they'd heap it high, even while attempting to 'count calories' and practice self-restriction. This seems more of a problem when the food item is a 'reward' or treat, eg. ice cream.

      It occurs to me to wonder if some similar inability to judge 'rewards' might influence gambling addiction (which at least observationally appears to be mostly a male problem).

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      • (Score: 2) by migz on Sunday July 20 2014, @10:40AM

        by migz (1807) on Sunday July 20 2014, @10:40AM (#71466)

        There might be something to this. I am by no means a STEM person, but I do have a bit of an above average handle on the math.

        I know people look at the nutritional labels and see 10 Calories per serving, but the serving size is 30 g in a 500 g packet. They then eat the whole packet. And they think "it's diet food", so its ok.

        They have trouble with proportion, and volume. Now the school system is partly to blame, but releasing inmates without the ability to multiply and divide, but that's not all there is to it. The context around food is not one of hunger, but it becomes emotional and food serves as a Pavlovian reward. The circuit is built up.

        Now in the experiment this circuit can be measured as it distorts the measured behavior. The curious thing is the gender bias? It this circuit in some way related to biology, or is it social? Did they find any men who matched this behavior? And btw what is the proportion of men who are obese compared to women?

        • (Score: 4, Interesting) by Reziac on Sunday July 20 2014, @02:53PM

          by Reziac (2489) on Sunday July 20 2014, @02:53PM (#71512) Homepage

          The individuals I'm thinking of were perfectly capable of doing the math. They understood the concepts. But when it came to ladling it out, well, "their eyes were bigger than their stomachs". There was a fundamental disconnect between the volume in the dish and the *concept* of "how much should I eat", like it was a specific blindness. If you pointed out "that's too much" their response would be on the order of "what?? it's just one serving" with complete bafflement. Basically, the dish has to look "full" to be a serving in their eyes. (I guess one solution might be to only keep very small dishes in the house.)

          As to the gender bias, I expect that like just about every other 'psychological problem' that's really been examined at the biochemical level, it will prove to be genetic, and in this case strongly influenced by the hormone balance. (Quite possibly it's a =symptom= of a hormone imbalance.) DNA to RNA to enzymes to every bodily process is a direct chain of events, and a defective enzyme can have broad effects which vary depending on where the defect impacts a metabolic process. Frex, I know someone who had been misdiagnosed with a variety of mental issues, but what did the real problem prove to be? Porphyria, and because she has the "least defective" form of the relevant enzyme, it didn't announce itself as porphyria, but rather displayed a bunch of vague and largely psychological symptoms that went undiagnosed for years.

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          • (Score: 2) by HiThere on Sunday July 20 2014, @07:05PM

            by HiThere (866) Subscriber Badge on Sunday July 20 2014, @07:05PM (#71581) Journal

            FWIW, dish size is important enough that weight watchers, e.g., recommends using smaller plates. I'm not sure whether it's an always true or just for some people, but it's true often enough to have been noticed.

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            • (Score: 2) by Reziac on Sunday July 20 2014, @08:33PM

              by Reziac (2489) on Sunday July 20 2014, @08:33PM (#71614) Homepage

              Doesn't surprise me, and good on WW! Yeah, it's probably not every dieter, but enough of 'em to notice, obviously.

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        • (Score: 3, Interesting) by opinionated_science on Sunday July 20 2014, @04:08PM

          by opinionated_science (4031) on Sunday July 20 2014, @04:08PM (#71533)

          Yes, that is probably true. A more general problem, that was not addressed, is that the fact that so much food is prepackaged in quantities that are not necessarily "natural". By natural, think of a piece of fruit (an orange, apple etc..) and the sort of equivalent calorie source e.g. 50-100 calories. Now look at packages of fruit drinks, the concentration in the package makes them much more calorific.

          Some of this is learned behavior. Candy bars when you are a child, predispose us to think that is the quantity. But of course the industry wants to sell us more, so they mess with theses sizes. Sometimes to make us buy more (smaller per unit), but I strongly suspect they know that it will make some proportion buy more (to compensate for the smaller size).

          Fundamentally, the FDA propagates misinformation as their simply is insufficient data for actual basal metabolism. Checkout the table
          on page 14 of this usda document.
          http://www.cnpp.usda.gov/Publications/DietaryGuidelines/2010/PolicyDoc/Chapter2.pdf [usda.gov]

          3 levels of physical activity; sedentary, moderately active, active. Maximum ranges, Adult females 1800-2200 kCals/day , males 2000-3200, for ALL activities.

          This is clearly problematic, and here is an illustrative example. There have been clinical studies of marathon runners (>5000) to determine how much energy they consumed (actual consumption) and it was determined to be apx 3500kCals. Try running non-stop for an hour, that's about 900kCals (measured using my smartphone, but it is clearly not an outrageous estimate)

          Let's put this in context. This is 1 lb of fat (453g), minimum. The sedentary MALE range is 2400-2600 for all ages. Does this seem at all possible? You can sit around all day, and that is equivalent to 2/3 of a marathon?

          I know of examples of sedentary worker friend (in IT) who had his basal metabolism measured at 1200 kCals/day - he lost 100 lbs/18 months, with just diet. This is a non trivial personal change.

          It would appear the USDA numbers are highly optimistic, or otherwise the measurement criteria are not sufficiently diverse. There is unfortunately a perverse incentive for food/drink companies to promote consumption, perhaps even the government (they love our tax revenues).

          The science is there, the politics is always looking at ways of ignoring facts to suit opinion, or bribes.....

    • (Score: 2) by TGV on Sunday July 20 2014, @06:28AM

      by TGV (2838) on Sunday July 20 2014, @06:28AM (#71437)

      I haven't got mod points, but I think your explanation is quite likely. Something like avoidance or disinterest explains the results without having to invent new mechanisms. I think the experiment does correctly show that the effect comes from the learning phase.

    • (Score: 0) by Anonymous Coward on Sunday July 20 2014, @07:17AM

      by Anonymous Coward on Sunday July 20 2014, @07:17AM (#71445)

      As the submitter, thank you for pointing this out. Apparently I was too tired yesterday and didn't realize the only reward were the pictures, I thought the participants had been actually rewarded with the things in the pictures.