by Bob Roehr
Health
What makes you fat? Add your friends to a growing list of causes that includes genes, the microbes living in your gut, stress, the food that you put in your mouth, and the lack of exercise that doesn't burn off all those calories.
This latest study found that "a person's chances of becoming obese increased by 57 percent if he or she had a friend who became obese." The association was even larger than what was seen if a sibling (40 percent) or a spouse (37 percent) became obese, while your neighbor's weight only mattered if you were close friends.
It was drawn from the 12,067 adults who have been followed over 32 years as part of the Framingham Heart Study. The analysis was conducted by Harvard Medical School's Nicholas A. Christakis and the University of California San Diego's James H. Fowler. It appears in the July 25 issue of the New England Journal of Medicine.
"It's not that obese or non-obese people simply find other similar people to hand out with, rather, there is a direct, causal relationship," said Christakis.
"What appears to be happening is that a person becoming obese most likely causes a change of norms about what counts as an appropriate body size. People come to think that it is okay to be bigger since those around them are bigger, and this sensibility spreads," along with the waistline.
Fowler said, "It's about people's ideas about their bodies and their health…Social effects are much stronger than people have realized." You don't even have to see your friends on a regular basis for it to have an effect, they can live hundreds of miles away.
The study found, "pairs of friends and siblings of the same sex appeared to have more influence on the weight gain of each other than did pairs of friends and siblings of the opposite sex…it seems likely that people are influenced more by those they resemble than by those they do not."
When asked if they observed any difference according to sexual orientation, Christakis said, "That's a great question. Sadly, we have no data on the sexual orientation of anyone in the study." All of the participants naming spouses named members of the opposite sex, "so if there are gay couples in the study, they would not show up as spouses," Fowler added.
Stress
There is a growing appreciation that stress, in combination with a high fat diet, can be a significant generator of body fat and metabolic syndrome that is the precursor to diabetes.
Georgetown University researcher Zofia Zukowska has conducted basic research that identified at the cellular level a stress-associated pathway involving the signaling molecule neuropeptide Y and its cellular receptor. It was published in advance online on July 1 in Nature Medicine.
The work to date has been with mice under stress tests; they only added fat if they were on a high fat diet while under that stress. When the researchers injected into the fat deposits a molecule that blocked the receptor to neuropeptide Y, the fat melted away over a period of weeks even though the animals continued on the fatty diet and under stress.
Dr. Zukowska does not see this as a potential magic bullet to "cure" fat. She said, "I strongly believe that the only sustainable way to prevent or treat obesity is to change life style. But the pharmacology is a beautiful, encouraging step" that can help people see results quickly and encourage them to maintain a more beneficial lifestyle.
It will be years before trials involving neuropeptide Y begin in humans, and substantially longer before a product may become available in the market.
"We hope that our study will help raise awareness of the fact that stress has tangible effects, and therefore addressing stress, whether through exercise, medication, or whatever a person's affinities are, is an important part of combating obesity," she said. These are things that you can do now.
