and within society. We have analyzed pioneering movements such as one to prevent childhood obesity and another to reduce heart disease risk in midlife women. Most recently, we studied the strategies of women across the country who have successfully improved the nutrition and physical activity environments in their own communities and beyond. I consider these women “game changers.” They offer inspiration and practical guidance on harnessing social networks to generate lasting positive change in their own lives and in the world at large.
Women, it seems, are powerful catalysts—in large part because of their effective use of social networks. One woman, Deanne, tackles her own obesity by altering her personal environment and then urges others like her toward similar life-shifts. Neelam brings gardens and fresh produce to inner-city Los Angeles and unites with likeminded community members to oust sugar-sweetened beverages from schools. Barbara joins with citizens and city planners to create the concept of “complete streets” to foster walking and biking to work. Jill recruits young high school graduates to help improve recess and active play in schools around the country. And Carla develops a program in Maine to get children and their families moving in the winter, a program that has been adopted by most northern states. Throughout the book, but especially in the final two chapters, you will read about and learn from these and other game-changing women.
There’s a New Yorker cartoon I’ve always loved. It shows a pack of wolves howling in unison at the moon. One wolf leans over and says to another: “My question is, are we having any impact?” Though people in my field have been working hard to get out the message and move people toward healthier habits, the mountain of physical inactivity and poor nutrition is bigger than ever. We need to make change now in this arena and in many others—hence the urgent call for each of us to become engaged in this effort.
Given how much is at stake and the scope of the challenges facing us, our generation understands that we can’t sit back and wait for things to change. We need to support one another. We’re already influencing the people around us. Now we need to do so in a more deliberate way, to spread positive change quickly. This is the beauty of social networks. They can help us do together what we cannot do alone. Not only can they support our own personal lifestyle changes, but they also are essential for creating large-scale change. We need to mobilize our collective energy to improve our own lives and the lives of our families, communities, and beyond. This is what it will take to create the big change we need in this country. Together, we can create an environment that promotes good health for one and for all.
Chapter 1. It’s a Complicated Web
When I give my talks to the public, I often show a series of maps of the U.S., year by year, from 1985 to the present. The effect is always shocking. The maps show each state in a color that indicates obesity rates—from cool, blue colors for low obesity to warm, fiery colors for high obesity. Over the 25 years, the overall color of the map gradually turns from light blue to darker blue to pale red to darker red, to bright orange. By 2009, most of the country is either red or orange, indicating that more than 30 percent of the population is obese. It looks like the spread of some horrible epidemic. And it is. What the map doesn’t show is that another 35 percent of our population is overweight.
Not long ago, my husband came to one of my talks. As we were driving home, he said, “Mim, you’ve been working in the field of nutrition for a long time, overlapping almost identically with the obesity maps you showed. I know you’ve been working hard, but what have you been working on? It’s a good question and one I’ve thought a lot about over the past five years. When I think of the billions of dollars that have gone into research, public health, and education since the mid-1980s, I have to ask, “Have we been focusing our efforts on the wrong target?” For years, we’ve emphasized individual responsibility. We need to refocus our lens in light of new research showing that these approaches don’t work if an individual’s social and physical environment remains unchanged.
Obesity Trends in U.S. between 1985 and 2009
THE SOCIAL NETWORK EFFECT
Over the past few years, innovative work suggests the surprising power of our environment in shaping our lives. Especially fascinating is research showing that our social environment—the network of people we spend time with, our family, friends, and peers—has a profound influence on our health and our health-related behaviors.
In 2007, researchers Nicholas Christakis and James Fowler of Harvard Medical School released a study that sent shock waves through the public health community. The study looked at 12,067 people tracked over more than three decades and found that the risk of becoming obese spread almost like a virus from person to person. Analyzing data from the Framingham Heart Study from 1971 to 2003, the researchers used sophisticated statistical modeling to examine whether weight gain in one person was associated with weight gain in his or her friends, siblings, spouse, or neighbors. Their findings: In married couples, if one member became obese over time, the likelihood of the other following suit increased by 37 percent. Among siblings, if a woman became obese, her sister’s risk rose by 40 percent.
Most astounding, however, was the impact of friends—even friends living far apart. In fact, the researchers suggested that friends have an even greater effect on people’s risk of gaining weight than their genes do. A person’s chance of becoming obese appeared to climb by 57 percent if a friend of the same sex became obese. (There was no effect found for neighbors or for friends of the opposite sex.)
It gets even more interesting. The closeness of the friendship matters. Among close mutual friends, if one friend became obese, the other friend’s chances of doing so increased by 171 percent.
Three additional studies support this “contagion” theory of obesity. A 2008 study reported results of an analysis of adolescents. In a school-based survey of 90,000 youth in grades 7 through 12, students were asked to list as many as 10 of their closest friends (5 male and 5 female). The study showed that an adolescent’s body weight correlated strongly with his or her friends’ body weights. The impact was strongest in girls and in adolescents with higher body weight.
Another 2008 study looking at 1,000 people in each of 29 nations in Europe also supports the theory that weight gain ripples through peer networks. The study revealed that people’s body weight tended to reflect the weight of those around them. The highest body mass index (BMI) for men, it turned out, is in Malta, Slovenia, and Greece; the lowest in Turkey, the Netherlands and Italy. For women, the highest is in Malta and the lowest, in France and Italy. But in all countries body weight has been increasing.
The most recent study was published in December of 2010. Intrigued by the Harvard study, Dr. Rena Wing and colleagues at Brown University decided to test the hypothesis on a younger group of people, ages 18 to 25. They surveyed 288 young men and women in Rhode Island. The results showed that overweight and obese men and women were more likely to have romantic partners, best friends, and casual friends who were also overweight. (They also observed that overweight and obese men and women with more social contacts trying to lose weight had a greater intention of losing weight themselves. If a friend is trying to lose weight, this seems to influence a young adult’s own desire to lose weight.)
Why
