Featured Research

from universities, journals, and other organizations

Obesity linked to circle of friends

Date:
July 9, 2012
Source:
Loyola University Health System
Summary:
A 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.

A Loyola study of high school students provides new evidence that a person's circle of friends may influence his or her weight.
Credit: Pavel Losevsky / Fotolia

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."


Story Source:

The above story is based on materials provided by Loyola University Health System. Note: Materials may be edited for content and length.


Journal Reference:

  1. David A. Shoham, Liping Tong, Peter J. Lamberson, Amy H. Auchincloss, Jun Zhang, Lara Dugas, Jay S. Kaufman, Richard S. Cooper, Amy Luke. An Actor-Based Model of Social Network Influence on Adolescent Body Size, Screen Time, and Playing Sports. PLoS ONE, 2012; 7 (6): e39795 DOI: 10.1371/journal.pone.0039795

Cite This Page:

Loyola University Health System. "Obesity linked to circle of friends." ScienceDaily. ScienceDaily, 9 July 2012. <www.sciencedaily.com/releases/2012/07/120709121321.htm>.
Loyola University Health System. (2012, July 9). Obesity linked to circle of friends. ScienceDaily. Retrieved October 23, 2014 from www.sciencedaily.com/releases/2012/07/120709121321.htm
Loyola University Health System. "Obesity linked to circle of friends." ScienceDaily. www.sciencedaily.com/releases/2012/07/120709121321.htm (accessed October 23, 2014).

Share This



More Science & Society News

Thursday, October 23, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Chameleon Camouflage to Give Tanks Cloaking Capabilities

Chameleon Camouflage to Give Tanks Cloaking Capabilities

Reuters - Innovations Video Online (Oct. 22, 2014) Inspired by the way a chameleon changes its colour to disguise itself; scientists in Poland want to replace traditional camouflage paint with thousands of electrochromic plates that will continuously change colour to blend with its surroundings. The first PL-01 concept tank prototype will be tested within a few years, with scientists predicting that a similar technology could even be woven into the fabric of a soldiers' clothing making them virtually invisible to the naked eye. Matthew Stock reports. Video provided by Reuters
Powered by NewsLook.com
Jet Sales Lift Boeing Profit 18 Pct.

Jet Sales Lift Boeing Profit 18 Pct.

Reuters - Business Video Online (Oct. 22, 2014) Strong jet demand has pushed Boeing to raise its profit forecast for the third time, but analysts were disappointed by its small cash flow. Fred Katayama reports. Video provided by Reuters
Powered by NewsLook.com
U.S. Issues Ebola Travel Restrictions, Are Visa Bans Next?

U.S. Issues Ebola Travel Restrictions, Are Visa Bans Next?

Newsy (Oct. 22, 2014) Now that the U.S. is restricting travel from West Africa, some are dropping questions about a travel ban and instead asking about visa bans. Video provided by Newsy
Powered by NewsLook.com
US to Track Everyone Coming from Ebola Nations

US to Track Everyone Coming from Ebola Nations

AP (Oct. 22, 2014) Stepping up their vigilance against Ebola, federal authorities said Wednesday that everyone traveling into the US from Ebola-stricken nations will be monitored for symptoms for 21 days. (Oct. 22) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Science & Society

Business & Industry

Education & Learning

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins