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Having an obese friend increases your chance of becoming obese
Having an obese friend increases your chance of becoming obese

July 25, 2007 (Insidermedicine) A person’s chance of becoming obese is greater if he or she has a friend or family member who is also gaining a lot of weight, according to research published in the New England Journal of Medicine.

The prevalence of obesity has increased by 8% over the past 30 years in the US, and 66% of adults are now overweight. The increase cannot be explained by genetics and has occurred among all socioeconomic groups. Obesity is a risk factor for a number of chronic diseases, including high blood pressure, diabetes, heart disease, osteoarthritis, sleep apnea, and cancer. Achieving and maintaining a healthy weight is important to reduce the risk of those diseases and improve overall health. 

In a study to determine how social networks influence obesity, researchers evaluated a social network of more than 12,000 people who underwent repeated measurements
over a period of 32 years as part of a large heart study. The study assessed the influence of one person’s weight on the other, and the role the sex, smoking behavior, and geographical distance of people in the social network played in the process of gaining weight.

They found that a person’s chance of becoming obese increased by 57% if someone he or she considered to be a friend became obese in a given interval. The risk rose by 171% if both the subject and the acquaintance claimed to be mutual friends. Among friends of the same sex, a man had a100% increase in the chance of becoming obese if his
male friend became obese, whereas the female-to-female spread of obesity was
not significant. The risk of becoming obese also increased among siblings of the same sex, but no significant association between friends or siblings of the opposite sex was observed. Among married couples, when one spouse became obese, the other was 37% more likely to follow. Smoking behavior and geographic distance did not seem to affect the spread of obesity in any group.

The spread of obesity in social networks appears to be a factor in the obesity epidemic, and understanding this phenomenon may help experts develop public health interventions to help people maintain a healthy weight.

Reporting for Insidermedicine, I’m Dr. Susan Sharma.