Category: Eating Disorders

— Children as young as ten are making themselves vomit in order to lose weight and the problem is more common in boys than girls, according to a study of nearly 16,000 school pupils published online early, ahead of print publication, by the Journal of Clinical Nursing.

The findings have prompted researchers to issue a warning that self-induced vomiting is an early sign that children could develop eating disorders and serious psychological problems, such as binge eating and anorexia.

They also believe that self-induced vomiting can be tackled by making sure that children get enough sleep, eat breakfast every day, eat less fried food and night-time snacks and spend less time in front of a computer.

Thirteen per cent of the 8,673 girls and 7,043 boys who took part in the research admitted they made themselves sick to lose weight. But the figures were much higher in younger children, with 16% of 10-12 year-olds and 15% of 13-15 year-olds vomiting. The figures fell to 8% in 16-18 year-olds.

The study of 120 schools, carried out for Taiwan's Ministry of Education, also found that 16% of the boys made themselves sick, compared with 10% of the girls.

"Our study, which was part of a wider research project on health and growth, focused on children who said that they had tried to lose weight in the last year" says lead author Dr Yiing Mei Liou, Director of Clinical Practice of the School of Nursing at National Yang-Ming University, Taiwan.

"It showed that self-induced vomiting was most prevalent in adolescents who had a sedentary lifestyle, slept less and ate unhealthily.

"Obesity is a growing problem in industrialised countries and is an increasingly important medical, psychosocial and economic issue. It's estimated that obesity among children and teenagers has nearly tripled over the last three decades and international studies have revealed worrying trends.

"For example, a study by the US Centers for Disease Control and Prevention, published in 2010, found that 4% of students had vomited or taken laxatives in the last 30 days to lose or stop gaining weight. And a South Australian study published in 2008 said that eating disorders had doubled in the last decade."

The Taiwan study found that 18% of the underweight children used vomiting as a weight-loss strategy, compared with 17% of obese children and 14% of overweight children. Normal weight children were least likely to vomit (12%).

A number of factors were associated with high levels of self-induced vomiting. For example, more than 21% of the children who vomited ate fried food every day, 19% ate desserts every day, 18% ate night-time snacks every day and 18% used a computer screen for more than two hours a day.

When the researchers carried out an odds ratio analysis, they found that using a computer screen for more than two hours a day increased the vomiting risk by 55%, eating fried food every day by 110% and having night-time snacks every day by 51%. They also found that children were less likely to make themselves sick if they slept more than eight hours a night and ate breakfast every day.

"Our study found that children as young as ten were aware of the importance of weight control, but used vomiting to control their weight" concludes Dr Liou. "This reinforces the need for public health campaigns that stress the negative impact that vomiting can have on their health and encourage them to tackle any weight issues in a healthy and responsible way.

"The findings also suggest that self-induced vomiting might serve as an early marker for the development of obesity and/or other eating and weight-related problems."

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Journal Reference:

1. Yiing Mei Liou, Ya-Wen Hsu, Jow-Fei Ho, Che-Hung Lin, Wen-Yen Hsu, Tsan-Hon Liou. Prevalence and correlates of self-induced vomiting as weight-control strategy among adolescents in Taiwan. Journal of Clinical Nursing, 2011; DOI: 10.1111/j.1365-2702.2011.03739.x

A University of Missouri researcher has found that eating a healthy breakfast, especially one high in protein, increases satiety and reduces hunger throughout the day. In addition, using functional magnetic resonance imaging (fMRI) the researchers found that eating a protein-rich breakfast reduces the brain signals controlling food motivation and reward-driven eating behavior.

"Everyone knows that eating breakfast is important, but many people still don't make it a priority," said Heather Leidy, assistant professor in the MU Department of Nutrition and Exercise Physiology. "This research provides additional evidence that breakfast is a valuable strategy to control appetite and regulate food intake."

In the study, Leidy assessed physiological hunger and satiety by measuring perceived appetite sensations and hormonal markers in combination with psychological reward-driven motivation to eat, using fMRI to identify brain activation in specific regions related to food motivation and reward.

The researchers decided to target 'breakfast-skipping' teens for two reasons, Leidy said. First, breakfast skipping has been strongly associated with unhealthy snacking, overeating (especially at night), weight gain and obesity. Second, approximately 60 percent of adolescents skip breakfast on a daily basis.

For three weeks, the teens either continued to skip breakfast or consumed 500-calorie breakfast meals containing cereal and milk (which contained normal quantities of protein) or higher protein meals prepared as Belgium waffles, syrup and yogurt. At the end of each week, the volunteers completed appetite and satiety questionnaires. Right before lunch, the volunteers completed a brain scan, using fMRI, to identify brain activation responses.

Compared to breakfast skipping, both breakfast meals led to increased fullness and reductions in hunger throughout morning. fMRI results showed that brain activation in regions controlling food motivation and reward was reduced prior to lunch time when breakfast was consumed in the morning. Additionally, the higher protein breakfast led to even greater changes in appetite, satiety and reward-driven eating behavior compared to the normal protein breakfast.

"Incorporating a healthy breakfast containing protein-rich foods can be a simple strategy for people to stay satisfied longer, and therefore, be less prone to snacking," Leidy said. "People reach for convenient snack foods to satisfy their hunger between meals, but these foods are almost always high in sugar and fat and add a substantial amount of calories to the diet. These findings suggest that a protein-rich breakfast might be an effective strategy to improve appetite control and prevent overeating in young people."

The article has recently been published online in Obesity. Funding for the research was provided by the National Institutes of Health.

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Journal Reference:

1. Heather J. Leidy, Rebecca J. Lepping, Cary R. Savage, Corey T. Harris. Neural Responses to Visual Food Stimuli After a Normal vs. Higher Protein Breakfast in Breakfast-Skipping Teens: A Pilot fMRI Study. Obesity, 2011; DOI: 10.1038/oby.2011.108

— Eating disorders are prevalent in the general U.S. adolescent population and are associated with other psychiatric disorders, role impairment, and suicidality, according to a report posted online March 7 that will appear in the July print issue of Archives of General Psychiatry.

Although the lifetime prevalence estimates of eating disorders from population-based studies of adults are relatively low, their severity and dramatic effects have been repeatedly demonstrated through elevated rates of impairment, medical complications, other illnesses, death and suicide, according to background information in the article. Little is known about the prevalence or correlates of these disorders from population-based surveys of adolescents.

Sonja A. Swanson, Sc.M., of the National Institute of Mental Health, Bethesda, Md., and colleagues examined eating disorders with data from the National Comorbidity Survey Replication Adolescent Supplement (NCS-A), a nationally representative sample of U.S. adolescents. The objectives of the study included determining the lifetime and 12-month prevalences of anorexia nervosa (AN), bulimia nervosa (BN), binge-eating disorder (BED) and subthreshold eating disorders; examining their sociodemographic and clinical correlates and patterns of comorbidity with other mental disorders; and to describe the magnitude of role impairment, suicidal behavior, and service use associated with these disorders. Sufficient information was available to define subthreshold AN (SAN) and subthreshold BED (SBED) among those youths who did not meet criteria for AN, BN, or BED. The sample included face-to-face interviews with 10,123 adolescents ages 13 to 18 years.

The researchers found that lifetime prevalence rates of AN, BN, BED, SAN, and SBED were 0.3 percent, 0.9 percent, 1.6 percent, 0.8 percent, and 2.5 percent, respectively; and the 12-month prevalence rates of AN, BN, BED, and SBED were 0.2 percent, 0.6 percent, 0.9 percent, and 1.1 percent, respectively. Regarding lifetime prevalence estimates, there were no sex differences in the prevalence of AN or SBED, whereas BN, BED, and SAN were more prevalent in girls.

The majority of respondents with an eating disorder met criteria for at least 1 other lifetime DSM-IV disorder (classification of mental disorders) assessed in this study across the lifetime, with 55.2 percent, 88.0 percent, 83.5 percent, 79.8 percent, and 70.1 percent of adolescents with AN, BN, BED, SAN, and SBED, respectively, endorsing 1 or more co-existing psychiatric disorders. Among adolescents with 12-month AN, BN, BED, and SBED, 97.1 percent, 78.0 percent, 62.6 percent, and 34.6 percent, respectively, reported impairment in the past 12 months; 24.2 percent, 10.7 percent, 8.7 percent, and 2.8 percent, respectively, reported severe impairment. Eating disorders were most strongly associated with social impairment. Nearly all of those with AN (88.9 percent) reported social impairment, and 19.6 percent reported severe social impairment associated with their eating disorder. Lifetime suicidality was associated with all subtypes of eating disorders.

Although the majority of adolescents with an eating disorder sought some form of treatment, only a minority received treatment specifically for their eating or weight problems.

"… this study provides key information concerning the epidemiology of eating disorders in the U.S. adolescent population. The prevalence of these disorders is higher than previously expected in this age range, and the patterns of comorbidity, role impairment, and suicidality indicate that eating disorders represent a major public health concern. Finally, these findings support the nosological distinction [classification of diseases] between the major subtypes of eating disorders as well as the importance of inclusion of the full spectrum of eating behaviors in estimating the magnitude and correlates of eating disorders in the U.S. population," the authors conclude.

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Journal Reference:

1. Prevalence and Correlates of Eating Disorders in Adolescents Sonja A. Swanson et al. Results From the National Comorbidity Survey Replication Adolescent Supplement. Arch Gen Psychiatry, March 7, 2011 DOI: 10.1001/archgenpsychiatry.2011.22

 A brain imaging study at the U.S. Department of Energy's (DOE) Brookhaven National Laboratory reveals a subtle difference between ordinary obese subjects and those who compulsively overeat, or binge: In binge eaters but not ordinary obese subjects, the mere sight or smell of favorite foods triggers a spike in dopamine — a brain chemical linked to reward and motivation.

The findings — published online on February 24, 2011, in the journal Obesity — suggest that this dopamine spike may play a role in triggering compulsive overeating.

"These results identify dopamine neurotransmission, which primes the brain to seek reward, as being of relevance to the neurobiology of binge eating disorder," said study lead author Gene-Jack Wang, a physician at Brookhaven Lab and the Mount Sinai School of Medicine. Previous studies conducted by Wang's team have identified a similar dopamine spike in drug-addicted individuals when they were shown images of people taking drugs, as well as other neurochemical similarities between drug addiction and obesity, including a role for dopamine in triggering desire for drugs and/or food.

"In earlier studies of normal-weight healthy people who had been food-deprived for 16 hours, we found that dopamine releases were significantly correlated with self-reports of hunger and desire for food. These results provided evidence of a conditioned-cue response to food," Wang said.

In the current study, the researchers suspected that binge-eating obese subjects would show stronger conditioned responses to food stimuli when compared with non-binging obese subjects.

"Understanding the neurobiological mechanisms underlying food stimulation might point us toward new ways to help individuals regulate their abnormal eating behaviors," Wang said.

The scientists studied 10 obese people with a clinical diagnosis of binge eating disorder, based on evaluations at St. Luke's-Roosevelt Hospital, and 8 obese subjects who were not binge eaters.

The scientists used positron emission tomography (PET) to scan the subjects' brains after injecting a radiotracer designed to bind to dopamine receptors in the brain. Because the tracer competes with the brain's natural dopamine to bind to these receptors, the signal picked up by the PET scanner provides an inverse measure of the brain's dopamine levels: a strong signal from the bound tracer indicates low levels of natural brain dopamine; a low signal from the tracer indicates high levels of dopamine in the brain.

Each subject was scanned four times on two different days to test the effects of food stimulation vs. neutral stimulation with and without pre-administration of a drug known to amplify dopamine signals. The drug, methylphenidate, blocks the reuptake of dopamine from brain synapses, allowing it to linger longer. In scans without methylphenidate, subjects were given a placebo drug.

In the food stimulation condition, research subjects' favorite foods were heated (if appropriate) and waved in front of their mouths and noses so they could smell and even taste tiny amounts swabbed onto their tongues. For the neutral stimulation scans, researchers displayed non-food-related pictures and inanimate objects such as toys and clothing items in close proximity so research subjects could smell them while lying in the scanner. In all cases, research subjects had been fasting for 16 hours prior to scans.

Results

Food stimulation with methylphenidate significantly increased dopamine levels in the caudate and putamen regions of the brain in binge eaters but not in the non-binge eaters. Subjects with the most severe binge eating disorder, as assessed by psychological evaluations, had the highest dopamine levels in the caudate.

Dopamine levels did not rise significantly in other brain regions or under any other condition (neutral stimulation with or without methylphenidate, or food stimulation without methylphenidate) in either group, and were not correlated with body mass index of the research subjects. Assessments of the levels of receptors for dopamine also did not differ between the two groups.

"So the key difference we found between binge eaters and non-binge eating obese subjects was a fairly subtle elevation of dopamine levels in the caudate in the binge eaters in response to food stimulation," Wang said.

"This dopamine response is in a different part of the brain from what we've observed in studies of drug addiction, which found dopamine spikes in the brain's reward center in response to drug-associated cues. The caudate, in contrast, is believed to be involved in reinforcement of action potentially leading to reward, but not in processing of the reward per se. That means this response effectively primes the brain to seek the reward, which is also observed in drug-addicted subjects," Wang said.

Inasmuch as binge eating is not exclusively found in obese individuals, the scientists believe further studies are warranted to assess the neurobiological factors that may differentiate obese and non-obese binge eaters.

This study was funded by the National Institutes of Health through the Intramural Program of the National Institute on Alcoholism and Alcohol Abuse and the General Clinical Research Center of Stony Brook University, using infrastructure supported at Brookhaven Lab by DOE's Office of Science.

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Journal Reference:

1. Gene-Jack Wang, Allan Geliebter, Nora D. Volkow, Frank W. Telang, Jean Logan, Millard C. Jayne, Kochavi Galanti, Peter A. Selig, Hao Han, Wei Zhu, Christopher T. Wong, Joanna S. Fowler. Enhanced Striatal Dopamine Release During Food Stimulation in Binge Eating Disorder. Obesity, 2011; DOI: 10.1038/oby.2011.27

— It can be a helpless and heartbreaking situation for families as they try to confront a family member with an eating disorder. What they may not know is that there's a society on the Internet that is dedicated to thwarting any recovery from this dangerous and possibly fatal behavior.

University of Cincinnati communication researchers are reporting on a new type of social support group as social networks grow on the Web. This emerging Online Negative Enabling Support Group (ONESG) surrounding the pro-anorexia movement is reported in the current issue of the journal, New Media & Society.

Members of this society embrace anorexia as a choice rather than acknowledging it as an illness. The ONESG pro-anorexia movement reflects four themes and uses several communication strategies to encourage anorexics to embrace their harmful and dangerous impulses, writes lead author Stephen M. Haas, a UC associate professor of communication. The themes are:

• Staying "true" to the anorexia movement — Forums and blogs invite members to discuss eating, binging and exercising, an "online confessional" of sorts where members can confess their guilt if they feel they have eaten too much or have not exercised enough to stay inline with the movement.
• Promoting self-loathing strategies — Websites encourage communications that not only involving loathing of the physical body, but also of one's inner being in confessing feelings of worthlessness and weakness. These negative rants are embraced by other visitors — a communication technique the authors say is unique to this community. Messages are accepted and not contradicted, building a shared identity in acknowledging each others' failures.
• Pro-anorexia advising — The two most common forms of advice involve dieting and dealing with confrontations from non-anorexics, such as family members who try to encourage healthy eating.
• Pro-anorexia encouragement — The fourth communication theme uncovered in these social networks involves encouragement. This can involve affectionate messages that foster group intimacy, offer tips and techniques to encourage anorexic behavior, and form a barrier against the disapproval of non-anorexic "outsiders."

In ONESG communications, there was a common ambivalence between self-loathing and self-encouragement. "Embracing the ambivalence of self-loathing and self-encouragement is an important strategy because it illustrates the inner turmoil that resides within pro-anorexia participants," the authors write. "They cling relentlessly to the idea that achieving a certain level of thinness will somehow remedy their feelings of worthlessness and undesirability; however, the means by which they attain this sense of value and belonging is stigmatized and deemed undesirable."

The researchers say this secret social network is strengthened by the anonymity of the Internet, which allows the exchange of extreme views. Interactions co-construct potentially dangerous, negative behaviors in a positive way that allows new, positive identities to be created. Affectionate messages create a bonding experience.

The authors write that as new social media emerges, it will be even more important to understand their role and impact on ONESGs. They add that understanding these communication strategies may also serve as a useful tool to break down obstacles to life-saving therapy.

"By gaining deeper insight, we can potentially increase our efforts to help those whose online interactions revolve around 'communicating thin,'" the authors write.

The researchers gathered their data by exploring general social networking sites and pro-anorexia specific websites that allowed public access. The websites and blogs were researched over a period dating from October 2006 to May 2007. The collected data was believed to be primarily from Caucasian women between the ages of 13 and 26.

Other authors who contributed to the study are Meghan E. Irr, University of Pittsburgh Medical Center; Nancy A. Jennings, UC associate professor of communication; and Lisa M. Wagner, a UC adjunct assistant professor of communication.

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Journal Reference:

1. S. M. Haas, M. E. Irr, N. A. Jennings, L. M. Wagner. Communicating thin: A grounded model of Online Negative Enabling Support Groups in the pro-anorexia movement. New Media & Society, 2010; 13 (1): 40 DOI: 10.1177/1461444810363910

Women suffering from anorexia or bulimia draw themselves with prominently different characteristics than women who do not have eating disorders and who are considered of normal weight. This has been revealed in a new joint study from the University of Haifa, Soroka University Medical Center and Achva Academic College, Israel, published in The Arts in Psychotherapy.

"The results of this study show that women suffering or prone to developing eating disorders, such as anorexia and bulimia, can be diagnosed with a simple and non-intrusive self-figure drawing assessment," explained Prof. Rachel Lev-Wiesel, Head of the Graduate School of Creative Art Therapies at the university of Haifa and a co-author of the study.

The research, conducted by Prof. Lev-Wiesel alongside Dr. Jonathan Guez, Shimrit Valetsky, Dr. Diego Kruszewski Sztul and Dr. Bat-Sheva Pener, examined 76 women, 36 of whom had been diagnosed as anorexic or bulimic; 20 had no eating disorders but were overweight, and 20 had no eating disorders and were considered normal weight. Each of the participants completed two standardized questionnaires for screening eating disorders and were then asked to draw themselves. Besides being asked to draw themselves, no guidelines or limitations were set for the drawing.

The research team then evaluated the drawings and found various differences between the groups in four aspects:

• The neck: women suffering from anorexia or bulimia tended to draw a larger neck, a disconnected neck or no neck at all;
• The mouth: this feature was more emphasized in drawings by women suffering from anorexia or bulimia;
• The thighs: women with eating disorders drew wider thighs than the other groups in the study;
• The feet: women with eating disorders tended to draw pictures without feet or with disconnected feet.

The study also revealed that self-figure drawings can differentiate between anorexic and bulimic women: those with anorexia tended to omit breasts from their drawings, drew less defined body lines and smaller figures relative to the page size.

In order to assess the reliability of the drawing test, the more pronounced results were compared with the two standardized eating disorders screening tests, and a very strong correlation was found between all the tests.

"Women suffering from eating disorders usually tend to hide their condition, even from their professional therapists. They often find it difficult to talk about their problem, so a non-verbal and non-intrusive tool such as a simple request for a self-figure drawing can become an important tool in creative art therapy," explained Prof. Lev-Wiesel.

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Journal Reference:

1. Jonathan Guez, Rachel Lev-Wiesel, Shimrit Valetsky, Diego Kruszewski Sztul, Bat-Sheva Pener. Self-figure drawings in women with anorexia; bulimia; overweight; and normal weight: A possible tool for assessment. The Arts in Psychotherapy, 2010; 37 (5): 400 DOI: 10.1016/j.aip.2010.09.001

The more time adolescent girls spend in front of Facebook, the more their chances of developing a negative body image and various eating disorders, such as anorexia, bulimia and exaggerated dieting. This has been shown in a new study from the University of Haifa.

Eating disorders include a wide spectrum of abnormal mental and behavioral conducts related to food and body weight, such as anorexia nervosa and bulimia nervosa. This study, conducted by Prof. Yael Latzer, Prof. Ruth Katz and Zohar Spivak of the Faculty of Social Welfare and Health Sciences at the University of Haifa, set out to examine the effects of two factors on the development of eating disorders in young girls: exposure to the media and self-empowerment.

A group of 248 girls aged 12-19 (average age: 14.8) took part in the survey. These girls were asked to provide information on their Internet and television viewing habits. Regarding the latter, they were asked to give the number of popular shows related to extreme standards of physical image (the "Barbie" model) that they watched. The girls also filled out questionnaires that examined their approach to slimming, bulimia, physical satisfaction or dissatisfaction, their general outlook on eating, and their sense of personal empowerment.

The results showed that the more time girls spend on Facebook, the more they suffered conditions of bulimia, anorexia, physical dissatisfaction, negative physical self-image, negative approach to eating and more of an urge to be on a weight-loss diet. Extensive online exposure to fashion and music content showed similar tendencies, but manifested in fewer types of eating disorders. As such, the more the exposure to fashion content on the Internet, the higher a girl's chances of developing anorexia. A similar direct link was found between viewing gossip- and leisure-related television programs (the likes of "Gossip Girl") and eating disorders in adolescent girls. The study also revealed that the level of personal empowerment in these girls is negatively linked to eating disorders, such that the higher the level of empowerment, the more positive the physical self-image and the lower the chances of developing an eating disorder.

In this study, exposure to the media and the consequential sense of personal empowerment was found to be associated to parenting practices. Girls whose parents were involved in their media usage; who knew what they were viewing and reading and where they were surfing on the web; who watched, surfed or read along with them; and who conducted cooperative and critical discussions with their daughters about the content of their surfing habits, showed more personal empowerment, forming a protective shield against eating disorders.

On the other hand, parents who were not involved in their media exposure, were not aware of the content that their daughters were consuming, and instead of sharing and becoming familiar with that content chose to limit or prohibit exposure, led to lower self-empowerment in their daughters. This, in turn, has a positive link to various eating problems and negative body image.

"Significant potential for future research and application of eating disorder prevention lies in an understanding of how parenting decisions can have effect on an adolescent girl's sense of empowerment and that enforcing a girl's sense of empowerment is a means to strengthening body image. This study has shown that a parent has potential ability to prevent dangerous behavioral disorders and negative eating behavior in particular," the researchers stated.

 Scientists in Connecticut have carried out one of the first psychological studies into eating disorders in Native American (NA) populations. The research, published in the International Journal of Eating Disorders, provides new insights into the extent to which Native American populations experience eating disorders, revealing that women are more likely to report behavioral symptoms then men, while challenging views that NA men and ethnically white men will experience different psychological symptoms.

The team, led by Professor Ruth Striegel-Moore from Wesleyan University in Connecticut, studied data taken from the National Longitudinal Study of Adolescent Health for over 10,000 men and women with a average age of 22. Of these, 236 women and 253 men were either Native American or Inuit.

Research into eating disorders in Native Americans has lagged behind research of other mental disorders, leaving many unanswered basic questions about prevalence in major demographic groups of populations indigenous to the US, including Native American, Native Hawaiian, or Alaskan Natives.

"Little is known about eating disorder symptoms in Native American populations for several reasons," said Striegel-Moore. "Even though the U.S. government recognizes over 500 NA tribes one of the biggest research challenges is to find an adequate sample size. Our aim was to examine the prevalence of behavioral symptoms of eating disorders in a public access database to get an initial estimate of the extent to which young NA adults experience such problems."

The team confirmed the theory that NA women were more likely than NA men to report behavioral symptoms of eating disorders, revealing that regardless of race, ethnicity or nationality, research consistently shows that women are more vulnerable to developing disordered eating behaviors or full syndrome eating disorders than men.

The team also found a parallel between NA women and ethnically white women when considering the prevalence of binge eating, purging and "ever having been diagnosed with an eating disorder."

"This commonality between NA and white women refutes the myth that eating disorders are problems that only affect white girls and women" said Striegel-Moore.

Finally the team found that there was no significant difference between NA men and ethnically white men, again demonstrating how the affects of eating disorders are not restricted by racial groups.

While this research was one of the first into the psychological effect of eating disorders in NA populations it can now lead to further, longer studies. The team's findings were based on 7 days which is shorter than similar studies conducted over 28 days. Further research will also be conducted into the attitudinal symptoms of eating disorders, compared to the behavioral symptoms being discussed in this paper.

"This research provides us with a first glimpse into the extent to which young adult NA populations experience behavioral symptoms of eating disorders," concluded Striegel-Moore. "In the eating disorder field this type of epidemiological study has lagged behind other research, but now we have a foundation to study the distribution of eating disorders and identify psychological risk factors in Native American populations."

 For parents wanting to reduce the negative influence of TV on their children, the first step is normally to switch off the television set. But a new study suggests that might not be enough. It turns out indirect media exposure, i.e., having friends who watch a lot of TV, might be even more damaging to a teenager's body image.

Researchers from Harvard Medical School's Department of Global Health and Social Medicine examined the link between media consumption and eating disorders among adolescent girls in Fiji.

What they found was surprising. The study's subjects did not even need to have a television at home to see raised risk levels of eating disorder symptoms.

In fact, by far the biggest factor for eating disorders was how many of a subject's friends and schoolmates had access to TV. By contrast, researchers found that direct forms of exposure, like personal or parental viewing, did not have an independent impact, when factors like urban location, body shape and other influences were taken into account.

It appeared that changing attitudes within a group that had been exposed to television were a more powerful factor than actually watching the programs themselves. In fact, higher peer media exposure were linked to a 60 percent increase in a girl's odds of having a high level of eating disorder symptoms, independently of her own viewing.

Lead author Anne Becker, vice chair of the Department of Global Health and Social Medicine at Harvard Medical School, said this was the first study to attempt to quantify the role of social networks in spreading the negative consequences of media consumption on eating disorders.

"Our findings suggest that social network exposure is not just a minor influence on eating pathology here, but rather, IS the exposure of concern," she said.

"If you are a parent and you are concerned about limiting cultural exposure, it simply isn't going to be enough to switch off the TV. If you are going to think about interventions, it would have to be at a community or peer-based level."

Becker hopes the paper will encourage debate about responsible programming and the regulation of media content to prevent children from secondhand exposure.

"Up until now, it has been very difficult to get people who produce media as entertainment to come to the table and think about how they might ensure that their products are not harmful to children," she said.

This is Becker's second study of media's impact in Fiji, which is an ideal location for broadcast media research because of the recent arrival of television, in the 1990s, and the significant regional variations in exposure to TV, the Internet and print media. Some remote areas in the recent study still did not have electricity, cell phone reception, television or the Internet when the data were collected in 2007.

Her first study found a rise in eating disorder symptoms among adolescent girls following the introduction of broadcast television to the island nation in 1995.

What makes Fiji a particularly interesting case is that traditional culture prizes a robust body shape, in sharp contrast to the image presented by Western television shows such as Beverly Hills 90210, Seinfeld and Melrose Place, which were quite popular in Fiji when television debuted there in the 1990s.

Girls would see actresses as role models, says Becker, and began noting how a slender body shape was often accompanied by success in those shows. This perception appears to have been one of the factors leading to a rise in eating pathology among the Fijian teenagers.

But until now, it was not known how much of this effect came from an individual's social network.

Nicholas Christakis, professor of medical sociology in the department of health care policy at Harvard Medical School, has studied the spread of health problems through social networks.

"It shouldn't be that surprising to us, even though it is intriguing, that the indirect effects of media are greater," Christakis said. "Most people aren't paying attention to the media, but they are paying attention to what their friends say about what's in the media. It's a kind of filtration process that takes place by virtue of our social networks."

Becker says that although the study focused on Fijian schoolgirls, remote from the US, it warrants concern and further investigation of the health impact on other populations.

This research was funded by the National Institute of Mental Health, Harvard University and the Radcliffe Institute.

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Journal Reference:

1. A. E. Becker, K. E. Fay, J. Agnew-Blais, A. N. Khan, R. H. Striegel-Moore, S. E. Gilman. Social network media exposure and adolescent eating pathology in Fiji. The British Journal of Psychiatry, 2011; 198 (1): 43 DOI: 10.1192/bjp.bp.110.078675

Hanging out with healthy friends could be the best way to keep fit. A study of 3610 Australian women, published in BioMed Central's open access International Journal of Behavioral Nutrition and Physical Activity found that physical activity and healthy eating behavior were both strongly affected by social norms.

Kylie Ball, from Deakin University, Australia, worked with a team of researchers to survey the 18-46 year old women. She said, "The importance of social environmental influences on health-promoting behaviors such as physical activity and healthy eating has been increasingly recognized. Ours is one of the first studies to demonstrate the association of both social support and social norms with physical activity and eating behaviors."

The researchers tested the extent to which a fashion for healthy behavior among a person's contacts could influence their own lifestyle. The women who took part in the study were asked to rate how much they agreed with statements like "I often see other people walking in my neighborhood" and "Lots of women I know eat fast food often." Those women who moved in healthier circles were in turn more likely to eat well and get more exercise. According to Ball, "These findings suggest that healthy behavior may be contagious. The potential to modify social norms as an intervention lever for promoting increased engagement in physical activity and healthy eating is worthy of further investigation."

Journal Reference:

1. Kylie Ball, Robert W Jeffery, Gavin Abbott, Sarah A McNaughton and David Crawford. Is healthy behavior contagious: associations of social norms with physical activity and healthy eating. International Journal of Behavioral Nutrition and Physical Activity,