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. To estimate the nature of the person-to-person spread of obesity as a possible factor contributing to the obesity epidemic, the researchers analyzed a densely interconnected social network of 12,067 people. These individuals were assessed repeatedly from […]