Grandparents who shower children with sweets and treats are to be targeted in the fight against childhood obesity.

Experts claim that youngsters who are looked after by grandparents are often given chocolate and sweets and are less likely to be taken outside to play.

The research, which looked at families in Edinburgh and Birmingham, also found that they tend to be more lenient with children and use screens or TV for entertainment.

The study recommended that grandparents could accompany expectant mothers to health visitor checks or midwife appointments to become better informed about making health choices for children.

Dr Bai Li, of the Institute of Applied Health Research at the University of Birmingham, who led the study, said: “In the UK, a quarter of working parents are relying on grandparents.

“We found some parents felt they could not criticise because they rely on the free care.

“We suggest grandparents who are going to be caring for children under the age of five are given a brief intervention. We can exploit the existing system of health checks given to pregnant women and young children by midwives and health visitors.

“We could ask them to bring grandparents to appointments. We could ask women what their intentions are for childcare, so we can find those who are going to be using grandparents. At the moment, women are not asked this.”

Almost a quarter of Scots children are overweight or obese by the time they start Primary One, while only three-quarters of Scottish children get an hour of physical activity each day.

Age Scotland chief executive Brian Sloan said a “common sense” approach was needed.

He added: “Grandparents should respect parents’ dietary requests for their children but there should also be discussions to understand where and when a grandparent can spoil their grandchildren - whether through experiences or food.

“Each family dynamic is different. The choice to include grandparents in health appointments should be an option, not a requirement, for parents.”

The Scottish Government said its plans to halve childhood obesity by 2030 include “providing information and advice for parents and carers - which can include grandparents - and training for frontline staff in services that work with them”.