Childhood bullying linked to weight gain

Being bullied in childhood increases your chances of being overweight in adulthood, according to research published this week in Psychosomatic Medicine.

Bullying of young people is a systemic problem both in schools and online: in 2015 the UK charity Childline held over 25,700 counselling sessions with children about bullying. While the physical and psychological effects can be dramatic, the long term implications are not so clear.

This research, coming during National Bullying Awareness Week in the UK, brings to light another negative outcome associated with childhood bullying.

"Children who are bullied are more likely to be overweight as young adults, regardless of a number of risk factors and independent of their weight in childhood." says Jessie Baldwin, from King's College London, the study's lead author.

Baldwin and colleagues found that children who had been bullied in both primary and secondary school were 1.7 times more likely be overweight when they turned 18, compared to their non-bullied peers.

61.7% of UK adults were overweight, or obese in 2014, so this research has implications for society as a whole. "Interventions that could prevent bullying may be able to reduce some cases of [being] overweight in the population." suggests Baldwin.

The researchers analysed data from the Environmental Risk Longitudinal Twin Study, which followed more that 2,000 children (1,000 twins), born in England and Wales between the years 1994 and 1995, from birth until they turned 18.  Bullying was determined by interviews with children, and their mothers, at the ages of 7, 10 and 12.

At 18 the participants had their body mass index (BMI), a measure of obesity found by dividing their weight by the square of their height, and their waist to hip ratio measured.  Overweight was defined as a person having a BMI and waist to hip ratio in the top 15% of the population.

By using twins the group were able to discount genetic predisposition for weight gain by seeing if identical twins, who have the same genetic make up, were both overweight at 18.

Bullying may be causing changes in the children's brains.

The prefrontal cortex is a region of the brain required for inhibitory control, stopping the body from doing certain activities such as eating. Other studies have found that children who suffer early life stresses, such as maltreatment, have smaller prefrontal cortices suggesting reduced inhibition.  Bullying may shrink this region, reducing people's control over their eating.

Bullying is not a new phenomenon, but with the advent of the internet bullying is now a 24/7 activity.  Cyberbullying follows children home beyond the school gates and creates permanent digital records of abuse, which can then go viral.  Were things better in the good old days when children ran across idyllic sepia countryscapes, free from selfies, smartphones and social media? 

Perhaps not.  A previous study from the same group found that children bullied in the 1960s had a higher risk of being overweight at age 45.  The amount of bullying had not changed either.  15% of those children born in the late 1950s were frequently bullied compared to 13% of the early 1990s cohort.

These studies taken together present a slightly depressing picture, one in which bullying is a constant of society.  They do however stress the importance of why bullying should continue to be tackled, to reduce both its prevalence and its long term consequences.