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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.
(Score: 3, Interesting) by Reziac on Sunday July 20 2014, @02:16AM
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).
And there is no Alkibiades to come back and save us from ourselves.
(Score: 2) by migz on Sunday July 20 2014, @10:40AM
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
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.
And there is no Alkibiades to come back and save us from ourselves.
(Score: 2) by HiThere on Sunday July 20 2014, @07:05PM
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.
Javascript is what you use to allow unknown third parties to run software you have no idea about on your computer.
(Score: 2) by Reziac on Sunday July 20 2014, @08:33PM
Doesn't surprise me, and good on WW! Yeah, it's probably not every dieter, but enough of 'em to notice, obviously.
And there is no Alkibiades to come back and save us from ourselves.
(Score: 3, Interesting) by opinionated_science on Sunday July 20 2014, @04:08PM
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.....