Category: Food & Eating

The Sugar Made Me Do It

Neuroscientifically Challenged had a great post awhile back, Every Sweet Hath Its Sour, reporting on research that basically equates modern, processed food with drugs.

Why? As the Duke Health news release tells us, “Researchers at Duke University Medical Center have discovered that the brain can respond to the calorie content of food, even in the absence of taste.” An even better title summarizing this research is “Tasteless Food Reward.”

This March 2008 Neuron paper “Food Reward in the Absence of Taste Receptor Signaling” by Ivan de Araujo, Albino Oliveira-Maia and colleagues shows that high-calorie food can directly reinforce the mesolimbic dopamine system. This result overturns that common assumption that what we eat relies on conditioned preference, pairing taste with the ingestion of a particular substance, say, cops and their donuts. This assumption has been used to great effect in evolutionary medicine research—we evolved in a fat-, sugar- and salt-limited environment, and today our evolved tastes drive our excessive consumptions of fast food in the modern world.

Now the modern situation appears even more dire, for calories alone can also reinforce food consumption, at least in mice “which lack the cellular machinery required for sweet taste transduction.” The Tasteless Food Reward editorial by Zane Andrews and Tamas Horvath tells us that “de Araujo et al. show that mice lacking functional ‘sweet’ taste receptors (trpm5−/−) develop a preference for sucrose by activating the mesolimbic dopamine-accumbal pathway, solely based on calorie load.”

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Michael Pollan, Energy, and Change

Michael Pollan, author of The Omnivore’s Dilemma: A Natural History of Four Meals (one of the best recent anthropology books in my mind, even if it’s not by an anthropologist), has an essay out today, Why Bother? It is part of the New York Times Magazine themed issue, The Green Issue: Some Bold Steps to Make Your Carbon Footprint Smaller.

In his essay Pollan sums up how we, as normal people with normal powers, might change our approach to energy dependence. In particular, he focuses on overcoming the sense of helplessness we often feel, arguing cogently that this sort of “dependence” has been instilled through increasing social and economic specialization and a universalist approach in economics and politics.

Pollan points to the importance of local doing, to How and not just Why, as a central way to break the specialization and universalist trap. By focusing on mindsets, behaviors, experiences, and life roles (sound familiar?), Pollan gets at the everyday dimensions of life that can work as much change as technology or global accords. We just have to do it ourselves, even as we cultivate new ways to encourage and support these everyday processes.

(Still, for those of you who prefer a more political economy take on the problems we face, see Pollan’s highly recommended pieces You Are What You Grow and Weed It and Reap, taking on the US food bill, agribusiness, and energy-dependent processed food.)

Here’s an annotated version of Why Bother?

Early in the essay Pollan writes, “For us to wait for legislation or technology to solve the problem of how we’re living our lives suggests we’re not really serious about changing — something our politicians cannot fail to notice. They will not move until we do. Indeed, to look to leaders and experts, to laws and money and grand schemes, to save us from our predicament represents precisely the sort of thinking — passive, delegated, dependent for solutions on specialists — that helped get us into this mess in the first place. It’s hard to believe that the same sort of thinking could now get us out of it.”

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The Buzz about Epigenetics: Genes, Behaviour and the Environment

Our contemporaries in Behavioural genomics and Neurobiology are suggesting that epigenetics may be the key to understanding how the environment interacts with genes to produce obesity, longevity, sterility, mental illness, and maybe even cancer. But what is epigenetics? And, why is it important to Neuroanthropology?

Epigenetic processes provide a way for environmental factors to affect gene activity. These processes involve the chemical modification of the genome resulting in an alteration of gene expression. While the underlying DNA sequence remains unchanged, the activity of particular genes can be turned on or off. Nutrition, exposure to toxins and other exogenetic mechanisms can all be potentially involved in epigenetic activity. These environmental influences can act upon RNA transcripts, cellular structures, DNA methylation/chromatin remodeling, and even prions. For example, smoking can effect your epigenome which is believed to result in some forms of cancer.

Human research into epigenetics can be fraught with ethical dilemmas, and can take a number of generations before sufficient data is produced. But, this is where anthropologists come in. Behavioural and environmental data coupled with social statistics from communities across the world can provide scientists with useful data for analyzing long-term mental and physical health in relation to the environment and corresponding socio-cultural behaviours. Such data is particularly useful when collected from communities exposed to biological disasters or specific nutritional limitations.

To study epigenetics inside the very cells of our body, where most anthropologists are not able to venture, there is another option. Now, for the first time in an insect species, epigenetic modification has been identified and functionally implicated. The recent sequencing of the honey bee genome in 2006 has allowed scientists to discover genes that mediate epigenetic effects.

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Experiments and Effort

Gina Kolata describes an experiment by Ethan Sims in her book Rethinking Thin, where Sims put thin people on a forced-eating diet. Sims wanted to know whether people “would have a hard time gaining weight.” Kolata’s description of Sims’ and other similar experiments (such as putting people on starvation diets) plays a central role in establishing one of her main points—obesity is a biological problem.

In his first experiment with college students, Sims found that “these subjects found it all but impossible to gain much weight; no matter how much they tried to eat, they just could not become obese.” Sims reasoned that perhaps the students raised their activity levels and were burning off more calories. “He thought of the perfect subjects, people who really have no chance to cheat and burn off calories: prisoners.”

The study volunteers in prison did indeed gain weight. “But producing obesity turned out to be much harder than Sims had anticipated. The men increased their weight by 20 to 25 percent, but it took four to six months for them to do this, eating as much as they could every day. Some ended up eating 10,000 calorie a day, an amount so incredible that it would be hard to believe, were it not for the fact that the researcher study had attendants present at each meal who dutifully recorded everything the men ate.”

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Successful Weight Loss

Is successful weight loss possible?  Beginning from the presumption of “will power,” no.  People who “diet” generally lose and gain weight in a yo-yo fashion, often with greater rebounds.  But some people do successfully lose weight and maintain that loss.  What makes them different, and what lessons does that hold for thinking about weight loss?

 

Let us start with this 2005 article by leading researcher Rena Wing and Suzanne Phelan.  Here’s the abstract:

There is a general perception that almost no one succeeds in long-term maintenance of weight loss. However, research has shown that 20% of overweight individuals are successful at long-term weight loss when defined as losing at least 10% of initial body weight and maintaining the loss for at least 1 y. The National Weight Control Registry provides information about the strategies used by successful weight loss maintainers to achieve and maintain long-term weight loss. National Weight Control Registry members have lost an average of 33 kg and maintained the loss for more than 5 y. To maintain their weight loss, members report engaging in high levels of physical activity (1 h/d), eating a low-calorie, low-fat diet, eating breakfast regularly, self-monitoring weight, and maintaining a consistent eating pattern across weekdays and weekends. Moreover, weight loss maintenance may get easier over time; after individuals have successfully maintained their weight loss for 2–5 y, the chance of longer-term success greatly increases. Continued adherence to diet and exercise strategies, low levels of depression and disinhibition, and medical triggers for weight loss are also associated with long-term success. National Weight Control Registry members provide evidence that long-term weight loss maintenance is possible and help identify the specific approaches associated with long-term success.

 

A 2001 review article by Rena Wing and James Hill makes their argument more explicit: “common behavioral strategies, including eating a diet low in fat, frequent self-monitoring of body weight and food intake, and high levels of regular physical activity.”

 

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Culture and Inequality in the Obesity Debate

So far in the posts I’ve done on obesity, I have been focused on the biology behind obesity.  Part of that is due to my class and what this particular section of the course covered—showing them a biological approach to a health problem.  But as I have been going over research on obesity, I’ve collected a number of links and articles on culture, social class, and obesity.  So I am going to share those here. 

Culture 

Let me say one thing.  In biomedicine and particularly in epidemiology, there is an overarching orientation towards the individual.  It is how treatment is planned, how data is collected and analysis proceeds.  This approach misses out on the central insight of culture theory—that aspects of our environment get bundled together due to accumulating human action and our cultural systems of meaning making.  Epidemiology, by separating out factors, has little recourse to understand the dynamics of these larger patterns.  At least in epidemiology, one alternative might be Nancy Krieger’s ecosocial framework (pdf), complemented by James Trostle’s Epidemiology and Culture and Carol Worthman and Brandon Kohrt’s Biocultural Approaches to Public Health Paradoxes. 

In any case, some cultural anthropology and obesity.  First, check out Gina Kolata’s article Chubby Gets a Second Look, including quotes from Emory anthropologists Peter Brown and George Armelagos, teachers of mine when I was in graduate school.  “Being thin really isn’t about health, anyway, but about social class and control.  When food was scarce and expensive, they say, only the rich could afford to be fat…  Those notions of fashion gradually gave way to a more streamlined physique… The body mass indexes of Miss America winners, according to a 2000 study, have been steadily decreasing since 1922, so much so that for most winners in the last three decades their indexes would cause them to be considered underweight.” 

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