This is an open-access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work, first published in the Journal of Medical Internet Research, is properly cited. The complete bibliographic information, a link to the original publication on https://www.jmir.org/, as well as this copyright and license information must be included.
Online pro–eating disorder (pro-ED) communities are considered harmful because of their detrimental effects on their users’ body dissatisfaction, dieting, and help seeking. To date, it is unknown to which extent participation in pro-ED communities affects users’ body weight and desired weight loss.
This study aims to investigate the changes in the current and desired body weight of users of a pro-ED community (r/proed) on the social media website Reddit over time.
Data on 1170 users and the unsolicited weight information they shared with the pro-ED community were collected over a period of 15 months. Linear growth models were used to model changes in the users’ current and desired BMI over time.
Both current and desired BMI decreased over time, with a predicted rate of 0.087 and 0.015 BMI points per week, respectively. Weight loss was moderated by the users’ activity level in the community, with more active users losing more weight. Users with a higher baseline BMI experienced greater weight loss, but even users with a very low baseline weight (BMI <17 kg/m2) lost weight during their participation. In addition, users decreased their desired weight over time, with many pursuing extremely low, unrealistic weight goals. Changes in the desired weight were moderated by the baseline current BMI and baseline desired BMI. Users with higher desired weight and lower body weight at baseline decreased their desired weight more over time.
This is the first study to demonstrate the detrimental effects of pro-ED communities in a longitudinal study based on a large data set of user-generated online data. The results extend the literature detailing the harmful effects of online pro-ED communities by showing users’ weight loss, decreases in desired weight, and that higher activity levels lead to greater weight loss. Users could be driven to pursue very low, unrealistic weight loss goals by images of very thin bodies presented in these communities.
Eating disorders (EDs) are severe mental disorders. Many individuals with EDs strive to lose weight to achieve a
Online pro-ED communities, also called pro-ana and pro-mia communities for anorexia nervosa and bulimia nervosa, respectively, are widespread over the internet and attract a large number of vulnerable or impaired users. These communities exist on social media platforms [
One of the central mechanisms through which ED behaviors are promoted in these communities is
But literature on the body weight and weight loss of users of pro-ED communities is scarce. Users show a variety of different body weights, with the majority having a weight in the healthy weight category as defined by the BMI classification of the World Health Organization (BMI: weight in kg/height in m2; underweight BMI: <18.5 kg/m2, healthy weight BMI: 18.5-24.99 kg/m2, overweight BMI: 25.0-29.99 kg/m2, and obese BMI ≥30 kg/m2 [
Individuals with EDs report lower desired weights than individuals without EDs [
An individual’s desired weight can change over time [
The level of user activity in a pro-ED community is positively associated with disordered eating and ED-related impairment [
Although the detrimental effects of pro-ED communities are frequently emphasized, studies demonstrating these effects longitudinally for users of a pro-ED community are lacking. This study aims at investigating the effects by modeling weight loss and changes in desired weight over the course of participation. In addition, although some studies have noted the existence of voluntarily shared weight information in pro-ED communities, the majority of studies used surveys or laboratory experiments to assess data outside of online communities. To our knowledge, this is the first study that uses data from a pro-ED community to calculate BMI and desired BMI and model their changes longitudinally.
In this study, we explored the pro-ED community r/proed on the social media website Reddit [
We hypothesize that participation in r/proed is associated with weight loss. In addition, we hypothesize that users set lower desired weights over time to align themselves more closely with the propagated thin ideal. Furthermore, we hypothesize that the level of activity in the r/proed is associated with the changes in BMI and desired BMI of the users. Highly active users are expected to lose more weight and decrease their desired BMI compared with less active users.
Data from the r/proed community and its users were collected over a period of 15 months between August 15, 2017, and November 14, 2018, until its ban. We assessed current and desired BMI using the values for height and current or desired weight at the time they appeared in the users’ flair in r/proed. The values in the flair had to be coded manually, as they could not be assigned automatically to one of the weight categories because of ambiguity of the category to which they belonged. In addition, the units for height and weight measurements were omitted from some flair requiring educated guesses to determine which measurement system was used. Three independent raters manually coded a third of the flair texts for height, body weight, and desired weight. All 3 raters also coded a common set of 322 flair texts to assess interrater reliability for height, current weight, and desired weight. The intraclass correlation coefficients (ICCs) were 1, 0.98, and 0.98. The variable representing activity levels was calculated as the average number of posts and comments a user writes in the pro-ED community per week. After rating, all values for height and weight were converted to meters and kilograms, respectively.
As the data accessed through the official Reddit application programming interface for this study were publicly available, no application for ethics approval was considered necessary. We do not report any personally identifying information in this paper to protect the privacy of all users.
We estimated separate linear growth models for the current and desired weights with individual measurement time points nested in users. The first available values for the current and desired BMIs of each user were treated as their respective baseline values. The variable time was calculated as weeks between the baseline and the respective time points. The current and desired BMIs were person centered around their respective baseline values. Baseline BMI, baseline desired BMI, and activity levels were grand mean centered and standardized. All linear growth models were estimated with maximum likelihood estimation and the Nelder-Mead optimizer using the R package lme4 [
We estimated four models for the current BMI by iteratively adding predictors in each model. The first model was an intercept-only model with random effects from users. This model was used to calculate ICCs to determine the amount of variance due to between-person differences. In the second model, a random slope and the fixed effect for time were added. In the third and fourth models, we added interactions of time with standardized baseline BMI and activity levels, respectively.
A similar procedure was adopted for the desired BMI values. The first model was an intercept-only model, whereas in the second model, time was added. The three following models added the interaction between time and the standardized baseline desired BMI, standardized first current BMI, and the activity level variable.
Interaction effects in the linear growth models were illustrated by simulations using the R package merTools. The graphs of the simulation results are provided.
A total of 16,241 different flair texts were created by 5372 users during the data collection period. Of the 5372 users, 4101 had to be excluded from the analysis because they had only one measurement point for the current and desired weight. We performed sanity checks of the coded data and excluded 13 users because they had unrealistic values for height, current, or desired weight, such as a goal weight of 0 or a current weight BMI of 100, or because their flair showed implausible changes over time, such as a height increase of 5 cm in 1 day. The final data set consisted of 1170 users with 5193 flair texts. The descriptive statistics of the sample are presented in
Demographics, participation characteristics, and baseline values for the current and desired weight of users of an eating disorder community on Reddit (n=1170).
|
Values | |||
|
||||
|
|
|||
|
|
Female | 891 (76.15) | |
|
|
Male | 63 (5.38) | |
|
|
Nonbinary | 25 (2.14) | |
|
|
Transgender | 9 (0.77) | |
|
|
|||
|
|
Value, mean (SD) | 22.54 (4.68) | |
|
|
Value, median (range) | 22 (13.60-59.00) | |
|
||||
|
|
|||
|
|
Value, mean (SD) | 4.44 (3.93) | |
|
|
Value, median (range) | 3 (2-62) | |
|
|
|||
|
|
Value, mean (SD) | 13.27 (14.67) | |
|
|
Value, median (range) | 7.59 (0.00-64.68) | |
|
|
|||
|
|
Value, mean (SD) | 7.68 (29.85) | |
|
|
Value, median (range) | 2.75 (0.0-759.32) | |
|
||||
|
|
|||
|
|
Value, mean (SD) | 164.91 (7.72) | |
|
|
Value, median (range) | 165.10 (142.24-195.58) | |
|
|
|||
|
|
Value, mean (SD) | 60.80 (12.42) | |
|
|
Value, median (range) | 58.29 (34.47-135.35) | |
|
|
|||
|
|
Value, mean (SD) | 22.32 (4.08) | |
|
|
Value, median (range) | 21.48 (14.20-46.74) | |
|
|
|||
|
|
Value, mean (SD) | 18.55 (2.33) | |
|
|
Value, median (range) | 18.31 (12.02-42.29) |
aOverall, 15.56% (182/1170) of users did not report their gender.
bOverall, 50.85% (595/1170) of users did not report their age.
cWeeks between the first and last flair of a user.
dNumber of posts and comments of a user per week.
eCurrent BMI = (current weight in kg)/(height in m2).
fDesired BMI = (desired weight in kg)/(height in m2).
The ICC for BMI, calculated using the intercept-only model, was 0.38, indicating considerable variance between users. Compared with the intercept-only model, the three subsequent models, each adding one additional predictor, showed marked improvements in the goodness-of-fit measures Akaike information criterion (AIC) and Bayesian information criterion (BIC). The fourth model had the lowest AIC and BIC values and thus was chosen as the final model (results for all four models are provided in
The final model shows that users lost weight over time, with a predicted rate of 0.087 BMI points per week. Users with a higher baseline BMI and higher activity levels experienced greater weight loss. The interaction between time and baseline BMI on weight loss is shown in
Linear growth models for the current BMI of 1170 users of an eating disorder community on Reddit.
|
Model 1 | Model 2 | Model 3 | Model 4 | |
|
|||||
|
Intercept | −0.473 (0.025) | −0.165 (0.013) | −0.169 (0.013) | −0.165 (0.013) |
|
Time | —a | −0.074 (0.004) | −0.072 (0.004) | −0.087 (0.005) |
|
Time×baseline current BMI interactionb | — | — | −0.044 (0.004) | −0.043 (0.004) |
|
Time×activity interactionb | — | — | — | −0.118 (0.020) |
|
|||||
|
Intercept | 0.512 | 0.068 | 0.068 | 0.069 |
|
Residual | 0.829 | 0.250 | 0.251 | 0.250 |
|
Slope | — | 0.011 | 0.009 | 0.009 |
|
|||||
|
Akaike information criterion | 15,172.918 | 10,504.541 | 10,387.654 | 10,353.948 |
|
Bayesian information criterion | 15,192.584 | 10,543.871 | 10,433.540 | 10,406.389 |
|
Log likelihood | −7583.459 | −5246.271 | −5186.827 | −5168.974 |
a—: not applicable.
bMain effects of baseline current BMI and activity were excluded from their models as their inclusion lowered the model fit
Interaction effects of time and baseline current BMI on current weight BMI change of 1170 users of an eating disorder community on Reddit.
Interaction effects of time and activity level on current weight BMI change of 1170 users of an eating disorder community on Reddit.
The intercept-only model for the desired BMI has an ICC of 0.41, which indicates substantial variance between users. The three subsequent models showed marked improvements in the AIC and BIC fit measures. Including the interaction of activity and the time variable (model 5) does not improve the model fit. Therefore, the fourth model was considered as the final model (
On average, users’ desired weight decreased by 0.014 BMI points per week. Those with average or above average baseline desired BMIs reduced their desired weight, whereas those with below average baseline desired BMI increased their desired BMI over time.
Linear growth models for the desired BMI of 1170 users of an eating disorder community on Reddit.
|
Model 1 | Model 2 | Model 3 | Model 4 | Model 5 | |
|
||||||
|
Intercept | −0.075 (0.021) | −0.003 (0.01) | 0.002 (0.017) | 0.002 (0.017) | 0.003 (0.017) |
|
Time | —a | −0.015 (0.003) | −0.015 (0.003) | −0.014 (0.003) | −0.015 (0.003) |
|
Time×baseline desired BMI interactionb | — | — | −0.017 (0.003) | −0.033 (0.003) | −0.033 (0.003) |
|
Time×baseline current BMI interactionb | — | — | — | 0.026 (0.003) | 0.026 (0.003) |
|
Time×activity interactionb | — | — | — | — | −0.010 (0.015) |
|
||||||
|
Intercept | 0.379 | 0.185 | 0.187 | 0.187 | 0.187 |
|
Residual | 0.534 | 0.335 | 0.336 | 0.335 | 0.335 |
|
Slope | — | 0.004 | 0.004 | 0.003 | 0.003 |
|
||||||
|
Akaike information criterion | 12999.600 | 11627.828 | 11593.609 | 11538.863 | 11540.415 |
|
Bayesian information criterion | 13019.265 | 11667.159 | 11639.494 | 11591.304 | 11599.411 |
|
Log likelihood | −6496.800 | −5807.914 | −5789.804 | −5761.432 | −5761.208 |
a—: not applicable.
bMain effects of baseline desired BMI, baseline current BMI, and activity were excluded from their models as their inclusion lowered the model fit.
Interaction effects of time and baseline desired BMI on desired weight BMI change of 1170 users of an eating disorder community on Reddit.
The interaction between baseline current BMI and time on desired BMI was positive, indicating that a higher baseline current BMI was associated with a slower decrease or even an increase in desired BMI over time.
Interaction effects of time and baseline current BMI on desired weight BMI change of 1170 users of an eating disorder community on Reddit.
This study is the first to investigate changes in the current and desired BMI over a period of 15 months using user-generated data from an online pro-ED community. We were able to demonstrate sustained decreases in the BMI of r/proed users over the course of their participation. Although baseline BMI moderated the effect of time, even participants with very low baseline BMIs of 15-17 kg/m2 still lost weight. The fact that even users with very low baseline BMIs lost weight over the course of their participation is alarming, as this exacerbates the risks associated with low body weight. However, weight loss is also related to clinical complications in individuals with body weight above the underweight category [
The interaction of baseline desired BMI and time (
In summary, the results strongly support the detrimental effects of participating in online pro-ED communities and point to the risks associated with these communities. In view of these risks, potential benefits such as receiving social support and reducing loneliness appear negligible [
Users’ average desired BMI at baseline was just above the cutoff for underweight and thus at a similar level to that of a sample of women with ED [
We could not identify the specific processes and factors that caused these effects and yielded weight loss or decrease in the desired BMI. Cross-sectional and experimental studies have shown that exposure to pro-ED communities is linked to increased dieting and body dissatisfaction; however, it is unclear whether these are enduring effects [
Our analyses show that a high number of users used features such as flair to self-report their height, current, and desired weight in the pro-ED community and that it is possible to reliably extract meaningful information on ED impairment from online ED communities. Although self-reports of weight and height can be inaccurate, users of pro-ED communities, young women and women with EDs, tend to report their height and weight more accurately [
In November 2018, the administrators of Reddit issued a ban on the r/proed community. Although the subject of this study no longer exists, we consider its results to be an important addition to the literature. They can inform our understanding of other newly created or existing communities with similar processes and effects to those in r/proed. After the ban of r/proed, almost immediately, new communities appeared in its place, with most of them being quickly taken down by Reddit’s administrators. One such community, r/EDAnonymous [
In general, it seems unlikely that it will be possible to ban pro-ED communities completely from the internet or even from major social media platforms, such as Pinterest, Instagram, and Tumblr [
Akaike information criterion
Bayesian information criterion
eating disorder
intraclass correlation coefficient
We acknowledge financial support by the Open Access Publishing Fund of Ruprecht-Karls-Universität Heidelberg.
None declared.