Put down the chocolate biccies, away with the sweets! Nanas and Grandads who look after the kids for long periods of time may be contributing to the children’s weight gain according to a new Finnish study.

Researchers from the University of Helsinki studied 9,000 families in the UK over a two year period with at least one young child who was between nine months and three years old.

Published in the journal Evolutionary Psychology, the study compared weights, childcare arrangements and children’s family backgrounds.

“Results show that children who were cared for mainly by their grandmothers between the ages of nine months and three years were more likely overweight at age three than children who were cared for by their parents” said Dr Antti Tanskanen from the university.

He continued, “A significant way that grandmothers may have increased their grandchildren’s survival rates in pre-modern and traditional populations was to improve grandchildren’s nutritional status”

“The grandmaternal support that improved children’s nutrition status may have significantly decreased child mortality. However, grandmaternal support in modern societies may detrimentally affect children because it may increase the likelihood of a child becoming overweight.”

The study found that young toddlers who frequently were in care by their grandparents were a fifth more likely to be overweight or obese compared to those who stayed in the care of their parents.

The latest figures from the National Health Service in the UK has shown that a third of children are obese when they leave primary school.