Toddlers who are underweight or malnourished could be at risk for developing anorexia nervosa in adolescence, warns a new study.

Anorexia nervosa is an eating disorder that makes people obsessive about their weight. The findings, led by researchers from the University of North Carolina in the US, showed that persistent low body mass index (BMI) in children -- starting as young as age two for boys and four for girls -- may be a risk factor for developing anorexia nervosa in adolescence.

In addition, a persistent high BMI in childhood may be a risk factor for later development of bulimia nervosa characterised by binge-eating and purging disorder. According to Zeynep Yilmaz, Assistant Professor, although eating disorders are psychiatric in nature, the study highlights the need to also consider metabolic risk factors alongside psychological, sociocultural, and environmental components. 

"The differences in childhood body weight of adolescents who later developed eating disorders started to emerge at a very early age -- way too early to be caused by social pressures to be thin or dieting," Yilmaz said. 

The reason could be that underlying metabolic factors that are driven by genetics, could predispose these individuals to weight dysregulation, said the study, published in the Journal of the American Academy of Child and Adolescent Psychiatry. 

There is a need to develop early detection tools that could be used as part of routine checks by all paediatricians. Indeed, the earlier the problem is identified, the better it can be managed, especially if support is provided to the family as a whole, rather than just the individual, the researchers suggested. For the study, the researchers analysed 1,502 individuals.