Children’s weight has little effect on mood, behavioural disorders

According to a new study, childhood BMI is unlikely to significantly affect children’s mood or behavioural disorders. It suggests that previous studies, which have shown a strong link between childhood obesity and mental health, may not have fully accounted for family genetics and environmental factors.
While children with obesity are more likely to be diagnosed with depression, anxiety, or attention-deficit hyperactivity disorder (ADHD), the nature of the relationship between obesity and these mental health conditions remains unclear. Obesity might contribute to mental health symptoms or vice versa.
Lead author Amanda Hughes, Senior Research Associate in Epidemiology at Bristol Medical School, University of Bristol, UK, said, “We need to better understand the relationship between childhood obesity and mental health. This requires teasing apart the contributions of child and parent genetics and the environmental factors affecting the whole family.”
The scientists examined genetic and mental health data from 41,000 eight-year-old children and their parents from the Norwegian Mother, Father, and Child Cohort Study and Medical Birth Registry of Norway. They assessed the relationship between children’s body mass index (BMI), a ratio of weight and height, and symptoms of depression, anxiety and ADHD. Hughes and her colleagues found a minimal effect of a child’s own BMI on their anxiety symptoms.
They also found conflicting evidence about whether a child’s BMI influenced their depressive or ADHD symptoms. Neil Davies, Professor at University College London, UK, said, “At least for this age group, the impact of a child’s own BMI appears small. For older children and adolescents, it could be more important.”
“Our results suggest that interventions designed to reduce child obesity are unlikely to make big improvements in child mental health. On the other hand, policies which target social and environmental factors linked to higher body weights, and which target poor child mental health directly, may be more beneficial,” Hughes concludes.