Category: Food & Eating

Tightening your belt on your mind

The New York Times has an opinion piece by Sandra Aamodt and Sam Wang, Tighten Your Belt, Strengthen Your Mind, on the implications of new research on ‘willpower.’ Daniel already noted this research in his post, Glucose, Self Control and Evolution, and linked to the original research paper, Self-Control Relies on Glucose as a Limited Energy Source: Willpower Is More Than a Metaphor.

The New York Times‘ piece discusses the possibility that spending discipline necessitated by economic hard times might lead to less ‘willpower’ when confronting weight control issues. The authors write:

The brain has a limited capacity for self-regulation, so exerting willpower in one area often leads to backsliding in others. The good news, however, is that practice increases willpower capacity, so that in the long run, buying less now may improve our ability to achieve future goals — like losing those 10 pounds we gained when we weren’t out shopping.

Specifically, the research team ‘found that people who successfully accomplish one task requiring self-control are less persistent on a second, seemingly unrelated task.’ In one study, subjects were either given radishes or freshly baked chocolate chip cookies before doing a puzzle (how did they get human ethics clearance for the cookies?!). The folks who ate the radishes lasted longer and were more persistent in experimental tasks than the cookie eaters, or those who were allowed to pass on the radish appetizer.

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On the Causes of Obesity: Common Sense or Interacting Systems

When you examine the data, most likely you will come to the sorts of conclusions that common sense indicated in the beginning: biology matters—some people can eat and not get heavy, others struggle with weight; what you eat matters, say fatty food versus fruits and vegetables; and how physically active you are matters.  One of the few curves thrown in might be obesity is shaped by lower socioeconomic status, but even that is not too surprising.

So, the question is not really what but why?  And that is a much harder question.

Let me first give you a laundry list of factors linked to obesity, based on my impressions of going over the research these past weeks.  They are more-or-less in order of importance: genetics, socioeconomic status, activity levels, early weight (at birth, by age seven), weight gain in early adulthood, restrictive/binge style of eating, calorie/fat dense vs. fiber/micronutrient dense foods, and social network/cognitive associations of eating and weight.  Other factors could certainly be added to this list, some perhaps shifted around, but it more or less represents an expansion on the common-sense model.

So, why?  Here are some ideas: 

-Weight gain canalizes (once you gain it, it is hard to lose it, especially for predisposed individuals)
-Activity moderates (but does not prevent—it pushes back against a tendency to gain weight)
-Early acquired eating patterns are hard to change: family and social environments affect diet habits, whether these environments favor higher calorie and fat dense foods or foods that have more fiber and micronutrients
-Food insecurity heightens excessive calorie intake and favors lower energy expenditure, especially in food-rich environments.  Food insecurity includes: restriction during gestation and abundance afterwards; restrictive/binging pattern; not having access to food, especially desired food; not eating breakfast.

Right now I am playing around with a three-systems approach to weight regulation: (1) a body-brain system that regulates energy expenditure and storage; (2) an appetite system, largely mediated by the brain but with direct influences from the body and environment; and (3) a cultural biology system, mediating things like eating patterns, body image, and expected exercise.

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Wednesday Round Up #5

Food, Drink and Exercise 

Eric Asimov, Can Sips at Home Prevent Binges?
Good discussion of families, teenagers and learning to drink responsibly at home

Nicholas Bakalar, Skipping Cereal and Eggs, and Packing on the Pounds
Breakfast helps keep most adolescents thin (or perhaps less hefty…?)

Ginger Campbell/John Ratey, Exercise and the Brain
Podcast discussion of Ratey’s book, Spark: The Revolutionary New Science of Exercise and the Brain, and how exercise helps the brain

UPenn Press Release, Images of Desire: Food and Drug Cravings….
Cravings, habits and memories…

UFlorida Press Release, Imaging Disorders of Desire: Opiates, Brownies, Sex and Cocaine
Interview with Anna Rose Childress

Race 

Adam Geller, Where Should Conversation on Race Start?
In our mixed reactions to Obama’s speech, and much more

Eduardo Porter, Race and the Social Contract
Diversity and investment in public infrastructure

Mireya Navarro, Who Are We? New Dialogue on Mixed Race
Navigating the tight space between racial divides

General 

Sue Sheridan, Random Bytes
Sue has her own round-up, including make-up wearing Neanderthals and the evolution of complexity

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Human Biology and Models for Obesity

In reviewing the research and public debates, I have come away startled by the depths of politics and misappraisal about the problem, and the need for human biology to counter this mix of science and morality.  So tonight I’ll write about three problematic things I outlined to my class today, and then show how human biology can provide a useful counter. 

Mind/body and nature/nurture dichotomies run rampant in both public and scholarly discussions of debate.  If it’s not willpower, then it is a biological deficiency.  Genetics causes obesity, or super-size-me environments.  These dichotomies are based on philosophical distinctions that are now centuries old.  They do not match up well with how our bodies, minds, and environments actually work. 

The moralization of fat and the politics of diet produce a tremendous incentive for bias, whether explicit or implicit.  Rhetorical arguments are never really rhetorical in the domain of obesity.  Results are tinged by claims of good and bad, of what’s ideal and what needs to be done.  Since thin-is-in, obesity must be bad, no matter the data; finding that miracle cure, whether it is a diet or surgery or drug, promises huge financial gains, so convenient theories are propped up. 

Suspect science results from both old dichotomies and from the moral politics of obesity.  The moral politics is heightened by the uses of science in establishing authority over a problem, whether it is the government, a medical association, restaurant businesses or soda companies. 

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Obesity: Mortality, Activity and More

So tomorrow is the big lecture covering some of the biology of obesity.  My attempt to provide a more comprehensive and better integrated view than Kolata’s Rethinking Thin, at least from an anthropological view (which includes both biological and cultural viewpoints, and for me, also brings in a qualitative focus on people’s experiences and behaviors).  Tonight I will cover three topics—the health risks of obesity, the role of activity and exercise in weight, and the mind vs. metabolism debate.  These complement previous posts on the Behavioral Biology of Obesity and Obesity and Genetics. 

Being fat kills, right?  That’s the predominant health message of the past decade or so.  Extra weight is as bad as smoking, and should be as vilified.  There’s just one problem.  The science doesn’t back up such a blanket statement.  Right now it looks like having a few (yes, a few) extra pounds is actually healthier than being too skinny, at least at the population level. 

Some of Kolata’s best writing tells us about the work of Katherine Flegal and colleagues, who used sophisticated population data and statistical work to ask a basic question, What is the health risk of being overweight?  Based on research published in 2005 by the Journal of American Medical Association, Flegal found that individuals who were overweight but not obese (a BMI between 25 and 30) had lower mortality rates than people considered “normal” by BMI standards (86,000 deaths less than expected).  For people with a BMI of 30 or greater, obesity accounted for 112,000 deaths per year, a very large number but quite less than previous estimates of around 400,000 per year. 

This research is well-summarized in this Medical News Today article, which states “the net U.S. death toll from excess weight is 26,000 per year. By contrast, researchers found that being underweight results in 34,000 deaths per year.”  Flegal and colleagues have gone on to provide a wealth of evidence, their own and others’, that confirms their basic point that being overweight is different from being obese, and less risky than generally assumed in the highly charged moral debate in the United States.  As always, there is criticism and controversy over the methods and results, which are well summarized in this piece at Partnership for Prevention and also at The Center for Consumer Freedom. 

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Neurosexism, size dimorphism and not-so-‘hard-wiring’

Cordelia Fine has a great short piece, Will Working Mothers’ Brains Explode? The Popular New Genre of Neurosexism, on the recent spate of work about the ‘female brain.’ In the article (which is short but worth reading, including for the other material she links to), she explores ‘several recent popular and influential books arguing for fundamental and “hard-wired” differences in male and female psychology.’ In her discussion, she doesn’t so much focus on the research itself but on the question, ‘What accounts for the success and appeal of the new field of neurosexism?’ I’m going to take this posting as a license to range all over the place on the ‘biology’ of sex differences, not just in the brain, as a way of thinking more about how culture and biology become inextricably entangled even in basic sexual differences, like say body size.

One explanation for neurosexim, according to Fine, is that ‘Most lay readers, of course, have neither the background nor the resources to question the many inaccurate and misleading claims made about gender differences in the brain,’ a discussion that we’ve already had on Neuroanthropology (both here and here). I especially like a quote that Fine borrows from Mark Liberman: ‘misleading appeals to the authority of “brain research” have become the modern equivalent of out-of-context scriptural fragments’ (originally on Language Log).

Fine presents the example: ‘The back cover of The Female Brain offers to explain why “a man can’t seem to spot an emotion unless someone cries or threatens bodily harm”. Were we to pick up a different sort of book that made an equally unusual sort of claim (a guide to pets, say, which promised to explain why cats can’t climb trees), we would immediately put it down and go in search of a more reliable text.’ It’s a great point; so much of our experience points to myriad exceptions to these neurosexist rules, and yet many of us don’t throw the books out immediately. Odd…

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