paola tubaro anamia insna sunbelt2014 st. pete's beach fl 22.02.2014

Body image and eating disorders behaviors. The effects of personal networks

Paola Tubaro!University of Greenwich, London & CNRS, Paris!

Francesca Pallotti!University of Greenwich, London!

Antonio A. Casilli!Telecom ParisTech & EHESS, Paris!

Thomas W. Valente!University of Southern California, Los Angeles!

Eating disorders and body image

•  Eating disorders are characterized by abnormal eating behaviors with either insufficient or excessive food intake and exercising to the detriment of physical and mental health.

•  Eating disorders are accompanied by distorted perceived body image.

INTRODUCTION

Self-perceived image affects individuals’ behavior

Source: A Brazilian campaign against anorexia

Body image and behavior

Networks, peer effects and body image

•  Peer pressure is know to be a significant contributor to body image concerns and eating attitudes (Costa-Font and Jofre-Bonetpeer, 2011).

•  "Teen girls' concerns about their own weight, about how they appear to others and their perceptions that their peers want them to be thin are significantly related to weight-control behavior“ (Mackey and La Greca, 2008)

•  We use a network perspective to look more closely at the social environment to establish the extent to which interpersonal relationships affect the perception of individuals with respect to their body image

Body image and peer effects

A personal networks approach

•  We use ego-centric network data collected through a web survey of 284 English- and French-speaking respondents with eating disorders (Research project: Anamia).

•  Network data include information on their broadly defined personal networks including face-to face and Internet-based networks.

Our approach

The online questionnaire

Questionnaire interface

•  In the online questionnaire, a graphical ego network applet enabled participants to draw their personal networks!

•  Two graphical networks each!

–  general personal network (school, family, workplace etc.)!

–  online personal network (forums, blogs etc.)!

General personal networks: using a visual sociogram

The ANAMIA study

•  Each graphical interface enabled participants to:!

–  Add alters, specifying name, gender, and qualification (friend, family member etc.)!

–  Position emotionally closest alters next to ego, and less close alters further away!

–  Draw ties between alters;!

–  Group alters in social circles (schoolmates, member of a sports team, participants in a forum etc.)!

Network structure and composition

The ANAMIA study

Some examples of personal networks

Personal networks as drawn by respondents

Personal network data

Ego-networks

•  We reconstructed 265 ego-networks •  Two types of network variables: 1. Structural :

–  Adjusted density – taking into account social circles –  Size – the number of all alters

2. Compositional: –  Online and offline alters (multiplexity) (Blau index) –  Level of intimacy (proportion) –  Gender (proportion and variance) –  Qualification (Blau index)

Data

Egos’ characteristics

•  Social, demographic and economic characteristics!–  age, gender, geographic location,

employment, qualifications, income, family structure, profession of parents, etc.;!

•  Body and health !–  Body image (how they see themselves, how

others see them, how they would like to look);!–  Body characteristics (current weight;

minimum and maximum weight achieved; desired weight; weight believed to be healthy for them; height; BMI); !

–  Exercise and sports practice; !–  Health (what eating disorder, if any; whether

currently or previously under treatment and if yes, for what diagnosis, with which professionals, and since when; the importance of health for them, for their families, and for their friends);!

Some basic descriptive statistics:!• 136 FR; 148 UK!• Gender: 95% women;!• Age: Average 21.7 (both FR and UK);!• Students: Average FR 66%, UK 69%;!• Workers: Average FR 34%, UK 41%;!• BMI is normal for 53.96% of participants; underweight for 27.55, overweight for 18.49%;!• Eating disorders: EDNOS (FR 47%, UK 45%); Anorexia nervosa (FR 17%, UK 34%); bulimia nervosa (FR 28%, UK 16%); Binge eating (FR 8%, UK 5%);!• Treatment: over 50% of the participants who reported an eating disorder are being treated now!

Self-perception & Body image

1.  If I had to describe myself, I would say that I look like (perceived body image - D) 2.  If I could choose, I would like to look as (ideal body image - C) 3.  People usually say that I look like (mediated body image - O)

Each of these variables is measured on a scale ranging from 1 – very thin silhouette – to 9 – corpulent silhouette.

1 2 3 4 5 6 7 8 9

Figure Rating Scale

Dependent variables

•  D – C: Difference between self-description and how one would choose to look;D – O: Difference between self-description and how people think others see them.

•  A positive difference would indicate that the respondent’s current body image is heavier than his/her ideal or mediated body image. A negative difference would indicate the opposite.

Data

MODEL

•  Two-stages econometric analysis. As a first step, discrepancies in the two forms of body image are modeled for the whole sample. Secondly, we evaluate the determinants of discrepancies in body image for individuals in different BMI categories.

•  Model: bivariate ordered probit model to account for the joint distribution of the two forms of body image distortions, as a function of both individual attributes and personal network characteristics.

•  For the analysis we used the bioprobit Stata program written by Sajaia (2008).

•  As our sub-samples consist of a limited number of observations, we check for the robustness of our models by applying a simple stochastic re-sampling procedure based on bootstrapping techniques.

Analysis

Results:

• Adjusted density has an effect on D-C. This result is also confirmed for the normal weight and overweight sub-samples.

• Size is significant only for over- and under-weight individuals.

• Relational proximity matters for D-C, for overweight only.

• Heterogeneity in sex also matters for over- and under-weight individuals.

• Proportion of females: negative effect for the underweight, positive effect for normal weight

Also:

• Positive effect of BMI (difference between individual BMI and country-level average BMI): The more corpulent I am relative to my general social environment, the more dissatisfied I am with my body image.

• Positive effect of medical treatment on both D – C and D – O.

• Negative effect of age: older people seem to have narrower gaps.

• Positive effect of doing sports on both D – C and D – O.

Effects of network structure and composition

• Effects of individual variables confirm findings from the literature (peer effects from social environment broadly interpreted)

• In addition, we find evidence of network effects on body image distortions

Conclusions

THANKS!

For more information: www.anamia.fr/en

Contact: coordination@anamia.fr, p.tubaro@gre.ac.uk, f.pallotti@gre.ac.uk

Twitter: @anamia