Navigation Links
New evidence for link between obesity and circle of friends

MAYWOOD, IL. -- A Loyola study of high school students provides new evidence that a person's circle of friends may influence his or her weight.

Students were more likely to gain weight if they had friends who were heavier than they were. Conversely, students were more likely to get trimmer -- or gain weight at a slower pace -- if their friends were leaner than they were.

Results of the study by David Shoham, PhD, and colleagues are published in the journal PLoS ONE. Shoham is an assistant professor in the Department of Preventive Medicine & Epidemiology of Loyola University Chicago Stritch School of Medicine.

A student's social network also influences how active he or she is in sports. (By social networks, researchers mean face-to-face friends, not Facebook friends.) "These results can help us develop better interventions to prevent obesity," Shoham said. "We should not be treating adolescents in isolation."

The study was designed to determine the reason why obesity and related behaviors cluster in social networks. Is it because friends influence one another's behavior? (This explanation is called "social influence.") Or is it simply because lean adolescents tend to have lean friends and heavier adolescents tend to have heavier friends? (This explanation is called "homophily, or more informally, "Birds of a feather flock together.") Researchers used a sophisticated statistical technique to determine how much of the link between obesity and social networks is due to social influence and how much is due to homophily. This statistical technique is called "stochastic actor-based model," or SABM.

The researchers examined data from two large high schools that participated in the National Longitudinal Study of Adolescent Health (Add Health). One school, referred to as "Jefferson High," is in a rural area and has mostly white students. The second school, "Sunshine High," is an urban school with a substantial racial and ethnic diversity. Students were surveyed during the 1994-95 school year and surveyed again the following school year. Researchers examined data from 624 students at Jefferson High and 1,151 students at Sunshine High. Previously, researchers not affiliated with the current study asked students about their weight, friendships, sports activities and screen time. The body size measure they used was body mass index (BMI), which is calculated from a student's height and weight. A BMI over 25 is considered overweight and a BMI over 30 is considered obese.

Researchers found that part of the reason why obesity clusters in social networks was due to the way students selected friends. But even after controlling for this friend-selecting process, there still was a significant link between obesity and a student's circle of friends. For example, if a borderline overweight student at Jefferson High School had lean friends (average BMI 20), there was a 40 percent chance the student's BMI would drop in the future and a 27 percent chance it would increase. But if a borderline overweight student had obese friends (average BMI 30), there was a 15 percent chance the student's BMI would decrease and a 56 percent chance it would increase.

The findings, researchers concluded, show that social influence "tends to operate more in detrimental directions, especially for BMI; a focus on weight loss is therefore less likely to be effective than a primary prevention strategy against weight gain. Effective interventions will be necessary to overcome these barriers, requiring that social networks be considered rather than ignored."

Shoham noted the study has several limitations. All of the measures were based on self-reported data, which has known biases. Social network studies are observational rather than experimental, which limits researchers' ability to call the associations causal. The model also makes assumptions about how friendships form, are maintained, and dissolve over time, and these assumptions could not be directly tested. Also, the data were collected more than a decade ago -- before Facebook and at a time when childhood obesity rates were much lower.

Nevertheless, Shoham believes these results add to the vigorous debate over the relative importance of selection and peer influence in network studies of health. "Our results support the operation of both homophily and influence," he said. "Of course, no one study should ever be taken as conclusive and our future work will attempt to address many of these limitations."

Contact: Jim Ritter
Loyola University Health System

Related medicine news :

1. Study of Retired NFL Players Finds Evidence of Brain Damage
2. Study shows no evidence medical marijuana increases teen drug use
3. WSU study finds overwhelming evidence of hidden heart disease in hypertensive African-Americans
4. Antiretroviral treatment for preventing HIV infection: an evidence review for physicians
5. Novel biomarkers reveal evidence of radiation exposure
6. More Evidence Bilingualism Aids Thinking Skills
7. Report says new evidence could tip the balance in aspirin cancer prevention care
8. Researchers find evidence of banned antibiotics in poultry products
9. Wayne State University researcher seeks to understand link between obesity, flu severity
10. The Alzheimer’s Caregiver™ - Bridges the Gap between Research and Care
11. The Alzheimer’s Caregiver™ Offers a New Educational Concept of Care That Bridges the Gap between Research and Caregiving
Post Your Comments:
(Date:11/25/2015)... ... 2015 , ... Beddit® has launched a new Android app for ... features a more intuitive SleepScore™ that rates sleep quality on a 100-point scale and ... created by a proprietary algorithm. Beddit analyzes the data to provide an easy to ...
(Date:11/25/2015)... (PRWEB) , ... November 25, 2015 , ... In an ... Resurrection Medical Center (RMC) in Chicago, IL, UV Angel is evaluating the efficacy of ... and surgical intensive care units (totaling 30 beds) from May 2014 through October 2015 ...
(Date:11/25/2015)... ... ... Today, Mothers Against Drunk Driving (MADD) learned that the number of ... time since 2011. In 2014, there were 9,967 fatalities involving an alcohol impaired driver, ... Traffic Safety Administration (NHTSA), 32,675 people were killed in traffic crashes in 2014. Drunk ...
(Date:11/25/2015)... Silver Spring, Md (PRWEB) , ... November 25, ... ... the Pulmonary Hypertension Association (PHA) announces the nation’s Periwinkle Pioneers, individuals and groups ... the history of this disease. The Periwinkle Pioneers, nominated by the public, will ...
(Date:11/25/2015)... , ... November 25, 2015 , ... ... announced that it has undertaken significant expansion of its current state of the ... is part of PharmaTech’s strategy to increase its manufacturing capacity as well as ...
Breaking Medicine News(10 mins):
(Date:11/26/2015)... , November 26, 2015 3D ... by 2022, according to a new report by Grand View ... Kidney Disease (CKD) which demands kidney transplantation is expected to ... cost effective substitute for organ transplantation. --> 3D ... by 2022, according to a new report by Grand View ...
(Date:11/26/2015)... November 26, 2015 ... the "2016 Future Horizons and Growth ... Testing Market: Supplier Shares, Country Segment Forecasts, ... their offering. --> ) ... "2016 Future Horizons and Growth Strategies in ...
(Date:11/26/2015)... November 26, 2015 ... adds "Global Repaglinide Industry ... Report on China Repaglinide Market, 2010-2019" ... data and information to its online ... . --> ...
Breaking Medicine Technology: