By Howard LeWine, M.D.
Obesity is contagious. It spreads from person to person, but not in the same way as germs or viruses. You don’t need to be standing near someone who is overweight to catch it. Obesity spreads to people who are socially connected to you, even if they live far away.
In the July 26 issue of the New England Journal of Medicine, two Harvard professors, Drs. Nicholas Christakis and James Fowler, published the results of a study that evaluated the impact of social networks on obesity. This study has caused quite a buzz. Perhaps the social connections we have with family and friends have as much influence on our body weight as genetics and individual behaviors.
The researchers looked at a vast social and familial network using data from the long-term Framingham (Massachusetts) Heart Study. Drs. Christakis and Fowler identified 12,067 Framingham people who had one or more social tie to at least one other person. Each of the individuals had periodic health evaluations between 1971 and 2003.
In addition to body measurements, each of the subjects provided other information that made the study possible. The Framingham people also filled out tracking sheets with the names and sex of siblings, spouses, neighbors, and friends, and information on the types of friendships. The researchers also collected data on smoking habits and the geographic distances between the home of each individual and his or her identified social and familial contacts.
Here are some highlights of what the researchers discovered:
- The risk of becoming obese was 37% higher when a person’s spouse gained too much weight.
- For people with obese brothers and sisters, obesity was 40% more likely.
- The chance that an individual would become obese rose by 57% if a close friend became obese.
- If the friend or sibling was the same sex, the obesity link was even stronger.
So, is this just saying that heavier people naturally gravitate toward each other, or as the say saying goes -- birds of a feather flock together? The study was not designed to determine which specific mechanisms within social networks influence weight gain, but there were some powerful clues. In the article, the authors suggest that “the psychosocial mechanisms of the spread of obesity may rely less on behavioral imitation (and local environment) than on a change in a person’s general perception of the social norms regarding the acceptability of obesity.”
Their findings reasonably support this suggestion. While weight gain in spouses, siblings, and friends had a large impact, weight gain in immediate neighbors did not. Also, it didn’t matter how close or far away friends and siblings lived. And siblings and friends of the same sex who became obese correlated with the highest risk of the connected person also becoming obese.
In addition, how friendships were defined by individuals mattered. In a friendship that was identified as bidirectional (each named the other as a close friend), when one gained weight, it was very likely that the friend would as well. But things change if you count someone as a close friend, but that person doesn't consider you in the same way. According to this study, you would be more likely to gain weight after that person becomes obese. However, he or she would not be more likely to gain weight if you gain weight first.
This study does not mean you should alter your connections with family and friends based on body weight. Social connectedness is too important for good health. For example, older people who are socially engaged tend to hold on to their cognitive abilities longer.
How can we use the results of this study in a positive way?
Have we become too accepting of higher body weights, using the unhealthy weight gain of our friends and families to justify weight gain in ourselves?
Do you think we can use social contagion to our advantage to help us keep body weights down, without becoming obsessed?
I look forward to your thoughts, ideas and reactions.
Howard LeWine, M.D., is a hospitalist at Brigham and Women’s Hospital in Boston, where he practices and teaches Internal Medicine. He is the Chief Medical Editor of Internet Publishing at Harvard Health Publications.
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Comments: 18
The buddy weight gain seems plausible; however I find myself losing weight lately and I have both chubby and thin family and friends. I lean toward the theory now that I am taking oral diabeties medication that my body is becoming more balanced. I admit I have eliminated most sugar, white flour and try to make a concious effort to eat healthy. But I cooked and ate healthy before watching my diet.
Your comments about chubby and thin family in friends is interesting. Like you, most of us do have a mix of body weights and types we associate with. The study looked at what happens in most clusters, but surely there were exceptions to the prime observations.
As usual, we need to learn a lot more about these social influences.
Perhaps everyone in your social network stays at a healthier weight than they would otherwise.
There are often underlying medical factors in addition to caloric intake that cause a person to be overweight, but even so, each person's decision to take control of their own health is their responsibility. We should not let any study dictate our relationships.
To make change, goal-setting is a first step. To me, it is important to think about what people want to do in their daily lives. If you say NOT something, you might as well just say the something, because you brought the topic up, and there it is.
Talking about how to make good eating attractive, convenient, and inexpensive appeals to me. So I talk about sources of omega-three's, and bring them with me for tasting. But I also talk about growing flax seeds. The plants are beautiful and have hung out with humans for eons. The pictures and descriptions from wikipedia are attractive. Not only can humans eat flax, but fine linen can be woven from fiber produced by the plant.
I brought stevia plants and let everybody taste a leaf. It is widely believed on the internet that an artificial-sweetener corporation tried to keep stevia out of the U.S. by posting an anonymous criticism of it with the FDA. But South American Indians have been using it as a sweetener for generations, and somehow common sense seems to have prevailed. I purchased the last two stevia plants from a local nursery. The group had been introduced to stevia by the health and wellness coordinator, who had brought little packets of it for our tea.
I talk about growing my own blueberries, grapes, mints for tea and so on. It so much more convenient and inexpensive to munch from my own yard. It also has the component of giving me a sense of accomplishment, even though God, the earth, and the weather were on my team.
The complex where the group meets could be beautifully landscaped with grapes and blueberries, instead of the ornamentals maintained by an outside contractor. Having grown up worried about money, I am not very fond of ornamental plants.
Regarding exercise, I am asking everybody to think about what kind of movements feel good to them and give them a sense of accomplishment. I ask them to think about how they see their animals moving. Cats and dogs stretch with such abandon and drama. Animals, especially dogs, can be good role models for a number of healthy practices in daily life.
I also warn them that exercise can be addictive, and that athletes who suffer injuries and have to stop are in grave danger of depression. When they stop, they stop generating the happy biochemicals stimulated by exercise.
One thing always bothers me about news like this- when a "study " is done, and findings are announced... Who paid for it? What controls were used? Who benefits? Jaded as it may sound, I have noticed, that when it comes to "medical breaktrhoughs", 9 of 10 times the studies precede some new drug, or medical marvel that will fatten the coffers of pharmecuetical companies. When information on origins of the study becomes clear...I 'll take another look at the findings.
Things I want to know, include: Did the people in the sampling share many meals? Did the particpants excercise? What is the age of the group-no not a median age..I want the ages.What is the stress levels, general and mental health...of the subjects? Until I know all the facts that may have a bearing on this finding... it's just another interesting correlation about friends & family , and their eating habits.
I'm certainly not going to give up any of my friends...lean..or not. :-)
Another factor I have seen in my medical practice, is one I call "food envy". By this I mean, people who find some physiologic or psychologic satisfaction with food will want what the other person may have (sort of a "keeping up with the culinary Joneses).
In my over 20 years of practicing medicine, I have confirmed what everyone already "knows"- there is no easy answer or quick fix to this problem. My suggestions usually revolve around changing one's lifestyle- one's paradigm, if you will. If you can learn to change your attitudes and behaviors toward food, you will slowly change yourself. That doesn't necessarily mean getting a whole new group of friends but perhaps adjusting the relationships you have with your friends as well as your foods to make for a healthier you, over all.
The tough question is what incentives should there be for a social network to make and stick with healthier lifestyle choices? It can't be just a contest to lose weight. And just thinking that if a couple people start losing weight in the group, others will start to do the same ...
But what if everyone in the group committed to family and friend gatherings that included smaller portions of food, more veggies, etc? Probably too idealistic, given our love of food, myself included, unless there was a tangible reward.
I was fascinated by the essay's information about how we influence each other. Did anyone read Malcolm Gladwell's The Tipping Point? Excellent easy read about social phenomenon like social networking. These studies that the book or this essay discuss offer no hard conclusions but rather new information about how people relate to each other. Ponderables are left to the individual.
If I apply the reasoning of the essay to education instead of weight gain then this is what I get: on my street, I am the only single woman living alone. I own my home. I am clearly independent and doing fine. I am well known to my neighbors, including their children. And, yet, while the neighbors and I are very friendly and involved with each other, I do not stand as a meaningful model for their children. My lifestyle does not represent one more way to consider as the children grow up and decide on their own way to be. Trust me that this is true. Why not? Because I am not part of any family or true friend network for them. I have lived among them for eleven years and it does not matter in terms of roles and livestyle modeling. I am alien. A reverse example that fits the essay's theme is my relationship with my twenty-something niece. I rarely see her. She lives in another state and, yet, is influenced by me. Her psyche accepts that there are many different positive family models, including single woman living alone. From there her choices are her own.
One of my conclusions is that I should stay alert to opportunities to push information and be a positive influence within my network of family and true friends. This is where I have the highest, strongest influence on the world.
In this case, I'm identifying myself with and communicating with a large group of people who are overweight, but the dynamic is really the opposite, as folks encourage good habits, good choices, and applaud each others' small or large successes in changing the habits we've picked up from whatever earlier venues.