Author: dlende

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. 

Continue reading “Obesity: Mortality, Activity and More”

Obesity and Some Behavioral Biology

All right, weight regulation is really damn complex.  I am going to admit that upfront.  It involves many of the things we’ve talked about on this website in reference to brains—the body, multiple brain systems, complex interactions, and so forth.  Sure, most of the research does not include much context or culture or even environmental interaction, but then again, the research is aimed at getting at some basic biology, at understanding the mechanisms and processes involved in weight regulation.

So, what do we have?  In no particular order other than my impressions from reviewing the literature, (1) the importance of body-based systems in appetite and weight regulation, (2) the usefulness of allostasis in understanding weight, energy, eating and activity regulation; (3) satiation and appetite as more important in obesity than energy balance, which generally plays a modifying role; (4) the need to consider weight gain and weight loss separately; (5) the role of physical activity might play in driving weight regulation; and (6) the considerable limitations of “will power” to affect any of the above points, due to how our brains and bodies are set up and the considerable mismatch between our western ideology of self and how we actually work.

In this post I’ll cover stuff on the first four.  See Greg’s comment on Genetics and Obesity for more on #5-Activity, and for now, I hope that the ability of cognitive control over hormone release and lower brain systems should at least be fairly obvious.  (As for getting all this done by yesterday, I had a senior colleague spring a surprise guest lecture on me—so that meant dropping lots of on-going stuff to get that ready… Excuses, excuses.) 

So, body-based systems.  Two hormones, leptin and ghrelin, play a powerful role in shaping energy regulation, eating and weight.  The trick is that leptin is released by white adipose tissue (fat) and gherlin by the stomach and intestine.  Both have direct effects in our brains, overturning our general view of the brain as a master organ.  Leptin and gherlin act in concerted fashion, like many regulatory systems in the body (e.g., sympathetic and parasympathetic peripheral nervous systems).  For example, Zigman and Elmquist (2003) (pdf) liken them to the Yin and Yang of body weight control.  They characterize leptin as “a molecular signal of energy abundance” and gherlin as “an important indicator of energy insufficiency.”  In mice, increasing circulating leptin can decrease food intake, while gherlin stimulates feeding.  However, neither has proven broadly effective as dietary drugs, because weight and energy regulation are not driven by one sole hormone except in rare genetic deficiency cases.

Continue reading “Obesity and Some Behavioral Biology”

Visiting Colombia

Colombia is one of the most amazing countries I know for travelers.  Everything a traveler might want—geographical regions from deserts to tropical rain forest, plains to high-mountain glaciers; human diversity from world-class art to world-class archaeology to colonial history, indigenous groups, and the most modern of metropolises.  And the people are warm, and the food plentiful and delicious. So it’s a pleasure to point to several recent articles that highlight the reactivation of tourism in Colombia. 

Today the New York Times covers Bogotá, the capital city of eight million located at 8200 feet, in its piece A Cultural Heart Beats Anew. 

Travel and Leisure covers the magnificent fortified colonial city, home of Gabriel Garcia Marquez, this month in Cartagena, A Hidden Retreat. 

And last November the New York Times covered visiting the incredible Tayrona Park, on Colombia’s Caribbean coast, in its piece In Colombia A War Zone Reclaims Its Past.  Tayrona, with neighboring Santa Marta, the hacienda of Simon Bolivar, the Guajira, and the Kogi indigenous group which lives in the mountains above, holds some wonderful memories.

Recent Deric Bownds

Deric Bownds has some recent entries which I’ve quite enjoyed.  Our Motor Adaptation as a Process of Reoptimization covers an article on how motor adaptation is not to return to some baseline, but to “maximize performance in that environment.”  An argument closer to both an evolutionary and an embodied view. 

Influence of Language on Brain Activity provides us with an article arguing that “language-processing areas of the brain are directly involved in visual perceptual decisions.” 

Awareness and Attention: Different Brain Processes points out that “subjective visual experience is shaped by the cumulative contribution of two processes operating independently at the neural level, one reflecting visual awareness per se and the other reflecting spatial attention 

And A Primer on Executive Function in the Prefrontal Cortex covers the functional neuroanatomy behind “flexible responses to situations with alternative choices.”

Wednesday Round Up #4

Books

Dr. Ginger Campell and her Brain Science Store
Ginger provides a handy Amazon collection of the books covered in her podcasts

Greg Mortensen and David Oliver Relin, Three Cups of Tea: One Man’s Mission to Promote Peace… One School at a Time
Building schools amid the Taliban, Americans and more…  Recently covered in the Diane Rehm show.  800+ reviews on Amazon, averaging in at the max 5 stars 

Brian Fagan, The Great Warming: Climate Change and the Rise and Fall of Civilizations
Drought is our great historical enemy, especially in dense populations… Recently reviewed in the NY Times 

Sandra Blakeslee & Matthew Blakeslee, The Body Has a Mind of Its Own: How Body Maps in Your Brain Help You Do (Almost) Everything Better
One reviewer: “The brain and the body are not separate entities, but are intertwined, interdependent, and interfunctional. Understanding this fact is essential to understanding how and why body maps work. This book explains that lucidly.” 

Stephen Kern, A Cultural History of Causality: Science, Murder Novels, and Systems of Thought
Literary murder and social history—how we view the causes of ourselves

Melody Petersen, Our Daily Meds: How the Pharmaceutical Companies Transformed Themselves into Slick Marketing Machines and Hooked the Nation on Prescription Drugs
Pharmaceuticals killing people, and companies marketing them more.  See an illuminating review here  

Vision 

Cognitive Daily, Fun With Point-Light Displays—And What That Says About The Visual System
Creating order out of dots… includes some good QuickTime videos

Mixing Memory, Language, Neuroscientific Evidence for the Influence of Language on Color Perception
Critique of imaging, importance of evidence, and our visual system

General 

Cordelia Fine, Will Working Mothers’ Brains Explode? The Popular New Genre of Neurosexism
Critique of the at times popular view that gender differences are “hard wired”

Brandon Keim, Brain Scanner Can Tell You What You’re Looking At
Functional imaging and a good computational program can “decode” the different photographs people see, reconstructing the content.   Worth a look!

Continue reading “Wednesday Round Up #4”

Genetics and Obesity

In my medical anthropology class, we’ve been reading Gina Kolata’s Rethinking Thin: The New Science of Weight Loss and the Myths and Realities of Dieting.  Kolata argues for a biological approach to obesity, that weight is largely under genetic control and that there is no ideal diet which is going to help all people lose weight.  In other words, Kolata is taking up the “nature” side of the nature/nurture debate, with a direct critique of the idea that if overweight people could simply use their willpower and follow the age-old recommendation of eat less and exercise more, they would be ideally thin like the beautiful people we see on television—the Brad Pitts and Angelina Jolies of the world. 

Kolata sums up these points in a very amusing interview on The Colbert Report.  As Fat Fu summarizes about Kolata, “you can actually learn something about the state of the science. And which don’t conclude with exhortations to diet or insinuations that fat people are lazy and ignorant. In fact she doesn’t think diets work.” 

I like Kolata’s book, which is why I assigned it in my class.  And I certainly see the weight of the evidence as supporting many of her main points: heritability and biological regulation of body weight, as well as the absurdity of an “ideal diet” that will simply work for everyone (that’s called ideology, folks).  But Kolata gives us an approach that recreates the mind/body and culture/biology dichotomies, and resorts to a genetic determinism that both obscures the genetics and doesn’t leave much room for anthropology.  For example, she uses one study, a classic one by Stunkard et al. in 1990, to tell us that “70 percent of the variation in people’s weight’s may be accounted for by inheritance,” which is greater heritability than with “mental illness, breast cancer or heart disease.” 

I’ll admit, I am not the biggest fan of twin studies.  They are generally done in western populations without much variance in environment or development and with relatively homogenous populations.  In public, these researchers generally claim the higher range of heritability estimates.  And perhaps most bothersome, these studies seem to provide us with a “why” that is not really there—“genetic” becomes tantamount to cause. 

Continue reading “Genetics and Obesity”