Can Children Catch Obesity From Their Friends?

Chicken and egg

As Childhood Obesity News noted yesterday, where adults and teenagers are concerned, obesity does appear to be a transmissible disease. Children of course can’t help being exposed to it in their earliest nurturing environments. Even if the grownups in their support system are fortunate enough to have escaped the most telling outward signs (and don’t weigh 300 pounds), obesogenic habits and beliefs are sadly apt to be “caught.” Kids don’t know any better and have no other home or lifestyle to compare things to. They tend to accept and imitate.

But once they’re out in the world, other forces come into play, and researchers are very interested in the chicken-or-egg question. In the most simplistic scenario, two major things are going on. There is social influence, which means that friends influence each other’s behavior. Then there is homophily, which can be summed up by another avian metaphor, “Birds of a feather flock together.” With homophily, there is an element of choice, whether conscious or unconscious, based on a feeling that, for instance, kids who like heavy metal music belong together.

Among teenage girls, another kind of friendship choice might be exercised, as a deliberate strategy. A pretty girl might pick a plain girl as her best friend, because the contrast enhances her own attractiveness. Or a slim girl might pal around with a heavier girl, because in comparison she looks even thinner. But this is an aberration that probably has little to do with the spread of obesity.

The influence of a social network can have either a positive or a negative effect on a person’s weight at any age. The American Academy of Pediatrics published a study titled “The Distribution of Physical Activity in an Afterschool Friendship Network.” Vanderbilt University scientists looked at data from a 12-week after-school program in which the 81 subjects varied in age from 5 to 12. They wondered how much a child’s network of friends can influence weight, and specifically, physical activity patterns. Their conclusion was that interventions in social networks could potentially lead to meaningful changes in a child’s level of activity. The opinion was based on this information:

The strongest influence on the amount of time children spent in moderate to vigorous activity in the after-school programs was the activity level of their immediate friends. Children were six times more likely to adjust to their friends’ activity levels than not, but children did not make or break friendships based on physical activity.

A more recent study was a collaboration between Colorado State University and the Institute for Health Promotion and Disease Prevention Research in California. They used data from the Pathways to Health, a school-based intervention program whose focus is on obesity prevention. Pathways borrows heavily from programs designed to prevent substance abuse; since drugs and hyperpalatable foods both activate the brain’s reward circuits, the connection with classical addiction is obvious.

Pathways to Health is an evidence-based program that deals with such areas as impulse control, emotional control, planning and organization, working memory, and other skills that come under the heading of executive cognitive function (ECF). In the area of food, these skills are amenable to modification:

Inhibitory control may allow an individual to inhibit food-related thoughts and behaviors within an environment or situation filled with cues for (over-)
consumption of snack foods. Emotional control may allow an individual to cognitively manage strong affect and behavioral impulses.

But when it comes to breaking sedentary behavior patterns such as excessive computer gaming, the literature says, “It may take considerable cognitive effort to inhibit these unhealthy behaviors.”

Your responses and feedback are welcome!

Source: “Social Networks Influence Obesity,”, 07/12/12
Source: “The Role of Social Networks in Pediatric Obesity,”, 5/28/2012
Source: “Childhood eating habits influenced by peers,”, 03/25/14
Source: “Translating evidence based violence and drug use prevention to obesity prevention: development and construction of the Pathways program,”, 03/13/12
Image by Mark Turnauckas

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About Dr. Robert A. Pretlow

Dr. Robert A. Pretlow is a pediatrician and childhood obesity specialist. He has been researching and spreading awareness on the childhood obesity epidemic in the US for more than a decade.
You can contact Dr. Pretlow at:


Dr. Pretlow’s invited presentation at the American Society of Animal Science 2020 Conference
What’s Causing Obesity in Companion Animals and What Can We Do About It

Dr. Pretlow’s invited presentation at the World Obesity Federation 2019 Conference:
Food/Eating Addiction and the Displacement Mechanism

Dr. Pretlow’s Multi-Center Clinical Trial Kick-off Speech 2018:
Obesity: Tackling the Root Cause

Dr. Pretlow’s 2017 Workshop on
Treatment of Obesity Using the Addiction Model

Dr. Pretlow’s invited presentation for
TEC and UNC 2016

Dr. Pretlow’s invited presentation at the 2015 Obesity Summit in London, UK.

Dr. Pretlow’s invited keynote at the 2014 European Childhood Obesity Group Congress in Salzburg, Austria.

Dr. Pretlow’s presentation at the 2013 European Congress on Obesity in Liverpool, UK.

Dr. Pretlow’s presentation at the 2011 International Conference on Childhood Obesity in Lisbon, Portugal.

Dr. Pretlow’s presentation at the 2010 Uniting Against Childhood Obesity Conference in Houston, TX.

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