Children looked after by their grandparents are more likely to be overweight and obese, a new study has found.
Researchers from the University of Helsinki, Finland studied 9,000 families in the UK and found that one in every three children aged three who were looked after by grandparents was obese.
The results flip tradition on its head: in the past, and in traditional societies today, grandparental care has always been crucial to improving child survival rates, 'The Independent' reported.
"Our results show that the same grandmother behaviour that may have had beneficial effects for grandchildren in our evolutionary past may have opposite effects in modern societies," researchers said.
"Grandmother investment aimed at improving grandchildren's nutrition in subsistence societies may have different outcomes in contemporary affluent societies," they said.
The researchers compared the weight of children at the age of three who were cared for mainly by their grandmothers with those cared for by their parents.
Overall, 23.6 per cent of the children were overweight. Among children who received primary childcare from their maternal or paternal grandmothers, 26.2 per cent were overweight, compared with 22.9 per cent who were looked after by parents.
That, according to the report, equates to a 31 per cent increased risk for children looked after by grandparents compared with those looked after by their parents.
The findings suggested grandparents were exacerbating the trend towards less healthy eating patterns, experts said.
Aric Sigman, a health education lecturer and psychologist, pointed to the fact that grandparents today are older than ever, which means "their nutritional understanding is from a different era so their simple understanding of what makes children fat is not as developed as that of later generations".
The study was published in the journal Evolutionary Psychology.