- \n
- pets are also getting obese – 58.3% of cats were obese in 2012<\/li>\n
- lab animals too are getting obese – 11.8% per decade from 1982 to 2003<\/li>\n
- is this due to antibiotic-mediated changes to gut bacteria that not just change how we digest, but also how we behave?<\/li>\n
- socially mediated effects?<\/span><\/li>\n<\/ul>\n
So surprising that a behavioral economist’s view could be so dismal.<\/p>\n
<\/p>\n
Source:\u00a0http:\/\/www.nytimes.com\/2013\/11\/10\/business\/the-co-villains-behind-obesitys-rise.html?_r=2&<\/a><\/p>\n
\nThe Co-Villains Behind Obesity\u2019s Rise<\/h1>\n
![\"\"](\"http:\/\/graphics8.nytimes.com\/images\/2013\/11\/10\/business\/10-VIEW\/10-VIEW-articleLarge.jpg\")
<\/p>\nWaltraud Grubitzsch\/European Pressphoto Agency<\/div>\nResearchers have compared tissue samples from obese mice with those of normal mice to try to determine which behavioral or biological factors might cause humans to gain weight. Here, a 2012 experiment in Leipzig, Germany.<\/p>\n<\/div>\n
By\u00a0SENDHIL MULLAINATHAN<\/h6>\n
Published: November 9, 2013<\/h6>\n
\nWhy is\u00a0obesity<\/a>\u00a0soaring? The answer seems pretty clear. In 1955, a standard soda at McDonald\u2019s was only seven ounces. Today, a medium is three times as large, and even a child\u2019s-size version is 12 ounces. It\u2019s a widely held view that obesity is a consequence of our behaviors, and that behavioral economics thus plays a central role in understanding it \u2014 with markets, preferences and choices taking center stage. As a behavioral economist, I subscribed to that view \u2014 until recently, when I began to question my thinking.<\/p>\n
For many health problems, of course, behavior plays some role but biology is often a major villain. \u201cBiology\u201d here is my catchall term for the myriad bodily mechanics that are only weakly connected to our choices. A few studies have led me to wonder whether the same is true with obesity. Have I been the proverbial owner of a (behavioral) hammer, looking for (behavioral) nails everywhere? Have I failed to appreciate the role of biology?<\/p>\n
A first warning sign comes from looking at other animals. Our pets have been getting fatter along with us. In 2012, some 58.3 percent of cats were, literally, fat cats. That is taken\u00a0from a survey<\/a>\u00a0by the Association for Pet Obesity Prevention. (The very existence of this organization is telling.) Pet obesity, however, can easily be tied to human behavior: a culture that eats more probably feeds its animals more, too.<\/p>\n
And yet, a study by a group of biostatisticians in the\u00a0Proceedings of the Royal Society<\/a>\u00a0challenges this interpretation. They collected data from animals raised in captivity: macaques, marmosets, chimpanzees, vervets, lab rats and mice. The data came from labs and centers and spanned several decades. These captive animals are also becoming fatter: weight gain for female lab mice, for example, came out to 11.8 percent a decade from 1982 to 2003.<\/p>\n
But this weight gain is harder to explain. Captive animals are fed carefully controlled diets, which the researchers argue have not changed for decades. Animal obesity cannot be explained through eating behavior alone. We must look to some other \u2014 biological \u2014 driver.<\/p>\n
Fittingly, the study is titled \u201cCanaries in the Coal Mine.\u201d Could our inability to explain animal obesity with behavior be a warning sign? Perhaps we are also overlooking biological drivers for human obesity. But what might these culprits be?<\/p>\n
A particularly interesting candidate resides in your gut. Your digestive system is actually a complex ecosystem, playing host to hundreds of species of bacteria that do things as diverse as fermenting undigestedcarbohydrates<\/a>\u00a0and providing\u00a0vitamins<\/a>. They also regulate how much fat your body stores.<\/p>\n
Not everyone, however, has the same gut bacteria. And, interestingly, the composition of this bacteria correlates with obesity. Of course, this relationship could be simple: the obese eat differently, and therefore they have different bacteria.<\/p>\n
But a\u00a0recent study<\/a>\u00a0in the journal Science showed that cause and effect could go the other way as well. Researchers harvested bacteria from pairs of human twins, where one twin was obese and the other was not. Then they transplanted these bacteria into mice. The mice who received bacteria from the obese twin gained weight, while the others did not. The mice did not eat more: Their metabolism changed so that they put on more weight even with the same caloric input.<\/p>\n
What, then, determines your gut bacteria? It could be\u00a0antibiotics<\/a>\u00a0or environmental toxins or how processed your food is. Another possibility is raised by a study in The New England Journal of Medicine\u00a0that shows<\/a>\u00a0that obesity seems to \u201cspread\u201d across social networks, with people infecting their friends and neighbors. I had always assumed that was because birds of a feather flock together \u2014 and that is surely part of the explanation.\u00a0But because gut bacteria can also spread among people in close proximity, perhaps the obesity epidemic really is, well, an epidemic?<\/p>\n
I\u2019m not arguing that behavior does not matter. Biology and behavior often interact; the spread of\u00a0flu<\/a>\u00a0depends on whether we wash our hands. Similarly, the bacteria study found that the \u201cobese gut bacteria\u201d had an impact only when the mice were fed diets heavy in saturated fats.<\/p>\n
Perhaps most interestingly, changing biology may even be changing cravings. Some biologists have hypothesized that our gut bacteria actually drive cravings for certain unhealthy foods. A focus on biology doesn\u2019t mean a reduced emphasis on behavior, just a richer understanding of it.<\/p>\n
These and other studies raise important possibilities, which deserve more research and attention. At the very least, we should invest as many obesity research dollars in uncovering and understanding these biological channels as we do in understanding behavioral channels. And this is a behavioral economist talking!<\/p>\n
After all, this could radically change the way we think about policies to curb obesity. As one newspaper editorial pronounced:<\/p>\n
\u201cA little town in Sweden has put a local tax on fat men. It is declared that \u2018the fat man stands accused by the very fact of his too solid flesh\u2019 (vide \u201cHamlet\u201d) \u2018of gluttony and laziness.\u2019 Millions of fat men throughout the world may rise up and denounce as liars the town councillor who drew up this cruel indictment and those who voted for it, but the gentler way of reproving them would be to point out the tritely recognised danger of generalisation in almost any statement of supposed fact. Not all fat men are lazy and gluttonous. Obesity is in many a congenital habit of body; in others a disease.\u201d<\/p>\n
That editorial\u00a0<\/a>was written in 1923, for the paper known as The Paris Herald. Maybe the writer was on to something.<\/p>\n
\nSENDHIL MULLAINATHAN is a professor of economics at Harvard.<\/p>\n<\/div>\n
\nThis article has been revised to reflect the following correction:<\/p>\n
Correction: November 17, 2013<\/strong><\/p>\n
Because of an editing error, the Economic View column last Sunday, about possible causes of obesity, misstated the source of bacteria that were transplanted into mice as part of an obesity study. The bacteria came from human twins, not from other mice.<\/span><\/p>\n<\/div>\n
<\/p>\n<\/div>\n<\/div>\n
\n\n\n\n\nA version of this article appears in print on November 10, 2013, on page\u00a0BU6\u00a0of the\u00a0New York edition\u00a0with the headline: The Co-Villains Behind Obesity\u2019s Rise.<\/h6>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"
This is a typically obtuse, academic view of obesity, breathlessly attempting to cite the immense complexity of the disease, capping it with a plea for more research dollars, or at least a reallocation of research dollars. There are a couple of interesting snippets: pets are also getting obese – 58.3% of cats were obese in … Continue reading A behavioural economist’s view on obesity…<\/span>