Is obesity contagious?
A recent study in the July 26th issue of the New England Journal of Medicine found a surprising link between obesity and relationships. The study revealed that the spread of obesity is often person-to-person in nature. A friend, sibling, or spouse, for example, of an obese person, all have an extremely increased chance of becoming obese themselves. The study focused on a group of 12,067 people with a body mass index of 30 or higher that were all a part of the Framingham Heart Study from 1971 to 2003. The specifics are as follows:
- Among Spouses, if one was obese, the other had a 37% increase in the chance of becoming obese.
- Among siblings, if one was obese, the other had a 40% increase in the chance of becoming obese.
- Lastly, and most shocking, among friends, if one was obese, the other had a 57% increase in the chance of becoming obese.
The study also found gender to be an important variable. Person-to-person connections among the same sex reported a much higher instance of shared obesity. Researchers theorize that the reason for shared obesity among person-to-person relationships is that those who are close to us, especially of the same sex, help us to determine what an appropriate body size is. The following is an excerpt of an article from Medpage today that further discusses the study:
Obesity tends to spread throughout a person’s social and family ties, even as far as a friend’s friend’s friend, researchers found.
When individuals become obese, it dramatically increases the chance that their friends, siblings, and spouse will also gain weight, Nicholas A. Christakis, M.D., Ph.D., of Harvard, and James H. Fowler, Ph.D., of the University of California San Diego, reported in the July 26 issue of the New England Journal of Medicine.
Surprisingly, the researchers found, the greatest effect was not among those sharing the same genes or the same household, but among friends, even those living apart.
What appears to be happening, the investigators said, is that obese persons change what they see as appropriate body size, and they come to think it is acceptable to be bigger, inasmuch as those among them are bigger, and this sensibility spreads. Other mechanisms might include food consumption, but the data did not permit a detailed examination of this factor, they said.