A study led by researchers at the Luxembourg Institute of Socio-Economic Research (Liser) and the London School of Economics (LSE) has found that children are at a increased risk of obesity after their parents' separation.

The study, published in the journal "Demography", found that the body mass index (BMI) of the children of separated parents tends to increase after the break-up The evolution of their BMI after separation is indeed greater than that of children of the same age living with both parents. The effect is particularly strong when the divorce occurs before the children reach the age of six years.

The study used data from the Millennium Cohort Study that tracks the lives of about 7,500 children born in the United Kingdom between 2000 and 2002. This study first collected data on the infant at nine months of age. then followed up at ages three, five, seven and eleven. In this sample, some 1,500 children (20%) experienced the separation of their parents.

Comparing the evolution of the BMI of these children with that of children living with both parents throughout their childhood, there was a more noticeable increase in body mass (and risk of overweight) after a divorce, as well as a difference that becomes significant about 24 months after separation.

The study took into account other factors that may be associated with both parental separation and weight gain, such as the socioeconomic context, as well as the natural biological evolution of BMI as a function of age and the sex of the children.

These results support many studies that have examined the detrimental effects that parental separation can have on different dimensions of child development, from cognitive skills to emotional and psychological well-being, to academic achievement. The authors concluded that, as the likelihood of children gaining weight increases with time after separation, "efforts to prevent children at risk of weight gain should begin early and soon after separation. Early intervention may help prevent - or at least mitigate - the process that leads some children to develop weight gain that can lead to obesity".