Can the Company You Keep Make You Fat? (Part 1)

When it comes to weight control, it’s probably been ingrained in you by now that eating too many calories without subsequently burning them off can cause you to gain weight. And that not doing enough physical activity can make you gain weight (or at least make it hard to lose weight). You’ve likely also heard theories suggesting that eating too much fat, or too much carbohydrate, or not enough protein can make you gain weight.


But the actual science of weight management is muddied by so many factors, including those that have little or nothing to do with food and activity. For instance, genetics, environment, and hormones all play a role. This helps to explain why you might be able to down 3,000 calories in a day without budging the scale an ounce, yet your spouse might eat half as much and weigh a pound more the next day. And now, another factor in weight control has emerged: your friends!

In 2007, a study was published in The New England Journal of Medicine by Nicholas Christakis, Professor of Medical Sociology at Harvard Medical School, and James Fowler, Associate Professor of Political Science at the University of California, San Diego. What they discovered is that if your friends have gained weight, you’re more likely to gain weight, too. Now, it’s been established that your family or spouse can influence your weight. But your friends seem to have more of an impact on your weight than your family — even if they don’t live nearby.

This study looked at more than 12,000 participants in the now-famous Framingham Heart Study (a long-term study meant to examine the factors associated with the development of cardiovascular disease). The subjects were asked to provide a list of family members and one close friend (many participants listed more than one friend); the patterns of weight gain over time in participants, family, and friends were then analyzed. The findings are interesting: When a person in the study became obese, the risk of his or her sibling becoming obese increased by 40%, and the risk for his or her spouse increased by 37%. If a subject’s friend became obese, the subject’s risk of becoming obese was raised by 57%. Furthermore, if the friends were of the same gender, the subject’s risk of becoming obese increased by 71%. If the friends were particularly close, the risk of obesity in the subject jumped up by 171%!

But there’s more. Even a friend of a friend or a friend’s sibling’s friend who gained weight could affect the subject’s weight.

What might come to mind as an explanation is that overweight people seek other overweight people to pal around with, just as thin people might prefer to hang around with other thin people. But that’s actually not the reason that the authors attribute to these findings. They point out that friends living many miles away can influence one’s weight. So, while genes can and do affect one’s tendency to be thin or heavy, genes haven’t changed enough over the years to explain why more and more people are obese in the U.S.

Certainly, large portions and the increased availability of fatty, processed foods, plus a lack of exercise, are contributors. Yet the authors of the study argue that social networking has had an impact on weight; thanks to e-mail, text messaging, Twitter, Facebook, etc., people are now easily able to stay connected to friends, even if they aren’t physically able to connect. Somehow, social networking seems to “transmit” weight control tendencies from one friend to another.

But it’s about more than just text messaging a friend. It may be that having friends who are gaining or losing weight leads a person to acquire similar attitudes and behaviors, and thus, social norms regarding body weight and what’s deemed as “acceptable” change. Your friends have more of an effect on your weight than you might think. No, friends aren’t going to pin you down and force feed you, or hold you at gunpoint until you run three miles. Rather, it’s what your friends eat and do that seems to influence what you eat and do. So, if your friends eat healthfully and exercise regularly, chances are you will too.

More next week! In the meantime, what are your thoughts on this topic?

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  • Norma P

    I just read this article about can the company you keep make you fat?
    My opinion– YES!

    I have a good friend that is also diabetic but when I am around her she is always munching on candy, chips and things that are loaded with carbs. I try and try not to eat them, suddenly I give in. Not all the time but at times when I get really down with my diabetes.
    I try so hard to be good on carbs and sugar content in things.. I do read the labels on boxes I buy.
    But my beautiful friend gets me in trouble every time. I try my best to tell her in nice way she can not eat those things… her attitude —
    oh well got to die from something.
    I cry every time..

    I have made a pack with myself.. NOT to eat things she offers. I can not do that anymore.
    I must think of me first.

    It is true if you go around with folks that eat things high in calories and snacks, you can get fat from it.

  • Too fat for friends

    All the fat slobs should be locked up and kept away from decent, clean-living thin people before they spread their gluttonous, lazy, weak willed habits to everyone.

    This is the second article in as many months on this site blaming fat people for making thin people fat. How about people stop looking for scapegoats for their issues? Or better yet, what about an attempt at understanding that due to genetic programming, controlling obesity is not simply a matter of “eat less, exercise more?” Some of us remain fat regardless of working out and eating well, and if we diet too much, our metabolism slows to nearly nothing.

    Obesity and diabetes are for the most part genetic disorders, not behavioral ones. If we put as much effort in dealing with that as we do in trying to guilt people into starvation diets, perhaps we could cure these problems.

  • Harry…………………….

    I’ve become so paranoid about making the people around me fat that I only serve green tea anymore.

  • Lorna

    I think it’s too easy to blame some one else for what we go through. Genetics has something to do with being over weight, but I believe if you really want to lose wieght, you have to put your foot down and have the will power to say “NO”. Every one needs friends, no matter if their fat or thin. I don’t blame my friends for me being over weight.

  • Jeanne

    I moved 2,000 miles from my home three years ago. All, and I mean that genuinely, of my new friends are thin. I’m afraind it has had no effect on me. I have gained 30 pounds in 3 years. Each time the dosage of one of my medicines is increased, I gain ten pounds I just cannot get off. These kinds of studies look at what large samples of our population do sociologically, not what really happens to individuals. Though I do wish the thin virus would spread to me.

  • George, Curious

    Jeanne’s comment about gaining weight when her meds got increased struck a chord. Many medicines can cause weight gain for a variety of reasons, including some commonly prescribed for diabetes. I once made the comment to my doctor that it was ironic that he kept telling me to be more active while simultaneously giving me meds that acted as sedatives.

  • Deb

    I blame our societies’ obesity problems on the food industry adding high-fructose corn syrup to virtually every thing we eat or drink. To not consume it, one has to drink only water and eat only fresh vegetables.

  • molly crew

    Can someone be obese and NOT be diabetic???

  • molly crew

    Also, my brother just had bariatric surgery and when the surgery was complete he no longer had hypertension or diabetes. Does anyone know how this happens? I beleive they “cut” the lower part of your intestines, but what does this part of the intestine have to do with having diabetes?

  • acampbell

    Hi Molly,

    To answer your first question, the answer is “yes.” One can be overweight or obese and not have diabetes. However, being overweight or obese is a risk factor for developing Type 2 diabetes. Fortunately, losing even 7% of your weight can lower the chances of getting diabetes. Also, bariatric surgery, while definitely helpful with managing diabetes, is not actually thought to “cure” diabetes. But the combination of the resulting weight loss, along with the bypass of the upper intestine, which plays a role in glucose regulation, can be effective enough to help lower glucose and A1C levels enough so that diabetes medicine can be stopped. Researchers are not necessarily saying that bariatric surgery is a cure, however. But for many people, it’s certainly a treatment option.