"Weight can be inherited, but it can also be contagious."
-- Brian Wansink, author or "Mindless Eating: Why We Eat More Than We Think"
Brian Wansink, an author of more than 100 academic articles and books on eating behavior, has found that when we are with people we enjoy, such as friends, we often lose track of how much, how fast and how long we are eating for. It seems when we are with others we tend to mimic the speed at which they eat and how much they eat.
Similarly, a new study published in the American Journal of Public Health suggests that obesity spreads socially not because friends have shared ideas about acceptable body size, but rather because they share environments and carry out activities together that may contribute to weight gain.
In other words, shared social behaviors, such as eating out at restaurants, and shared surroundings, likely play a bigger role in the obesity "friend effect" than do shared social norms.
Researchers interviewed 101 women and 812 of the their friends and family members (both men and women) and calculated the Body Mass Index for everyone in the study. The initial women in the study were 2.4 times more likely to be obese if their friends were obese. And they were 3.6 times more likely to be obese if their close friends were obese which confirms earlier findings that obesity spreads in social networks.
Participants were asked to choose their ideal body size from nine line drawings of people of different sizes. They were also asked how much they agreed with stigmatizing statements about obesity, such as "People are overweight because they are lazy." And they were asked whether they would rather be obese or have one of 12 other stigmatizing conditions, including herpes or alcoholism.
The researchers found very little support for the hypothesis that friends' shared views about acceptable body size cause obesity. Although friends tended to have similar BMIs, their views about body size did not account for this effect.
Therefore, this may suggest that interventions that try to change people's ideas about how fat or thin they should be won't be very effective.
Instead, efforts should focus on promoting healthy environments, for instance, making people's neighborhoods more exercise-friendly and increasing access to healthy foods, the researchers of this study say.
More studies need to be done to find out what accounts for the spread of obesity among friends, but, in the meantime, share these tips instead of fatty dips with your friends:
• Pace yourself with the slowest eater at the table
• Decide how much you want to eat prior to the meal
• Avoid temptation by always leaving some food on your plate as if you're still eating
Follow Joanna Dolgoff, M.D. on Twitter: www.twitter.com/joannadolgoffmd