Devoting just three or four extra minutes per day to family mealtimes helps to reduce the risk of childhood obesity.

Researchers from the University of Illinois have found that when low-income families spend longer at family mealtimes, their children's ability to maintain a healthy weight improves significantly.

In the US, the risk of childhood obesity is higher in low-income families with contributing factors including poor education, living in poor areas, little access to healthy food and being a single-parent family.

In the UK, 30.3 percent of children aged between two and 15 are either overweight or obese. A Foresight report says that if no action is taken, 25 percent of children in Britain will be obese by 2050.

Barbara H Fiese, director of the University of Illinois Family Resiliency Programme, said: "Children whose families engaged with each other over a 20-minute meal four times a week weighed significantly less than kids who left the table after 15 to 17 minutes.

"Over time, those extra minutes per meal add up and become really powerful."

The researchers observed 200 family mealtimes and tested the cumulative effect of socioeconomic factors and mealtime behaviours.

Mealtimes should be a priority

They looked at the importance families placed on sharing meals, efforts made to schedule family meals and whether or not families attached special meaning to eating meals together.

"Three to four extra minutes per meal made a healthy weight more likely," Fiese said.

Interaction was also found to be important, with families that placed special meaning on meals less likely to have an obese child.

Fiese suggests this research should be used as a method of intervention: "This is something we can target and teach. It's much more difficult to change such factors as marital status, maternal education, or neighbourhood poverty."

She said parents should be taught to value mealtimes and learn to make them a priority.

"It's also important to recognise the increasing diversity of families and their sometimes complex living arrangements that may challenge their abilities to plan ahead and arrange a single time to communicate with each other."

She added that programmes providing stress and time management, cooking lessons and parenting skills should be developed to help families reduce the risk of their children becoming obese.