Children who have televisions in their bedrooms are at an increased risk of becoming obese, a new study suggests.

In recent years, a number of studies have pointed to the importance of keeping televisions out of children's bedrooms. They suggest that excess TV viewing in childhood continues into adulthood, which can lead to a more sedentary lifestyle.

For this latest study, US scientists looked at almost 400 children and teenagers, aged five to 18. They were monitored specifically for issues relating to weight and fat, such as cholesterol levels, stomach fat, waist circumference and glucose levels.

Not surprisingly, the study found that children with a television in their bedroom watched more TV overall. However, it also found that these children had a higher waist circumference and more fat and subcutaneous adipose (fatty) tissue, than children with no TVs in their bedrooms. (Subcutaneous refers to fat that lies just under the skin.)

In fact, those with televisions in their bedrooms, along with those who watched more than two hours of TV per day, were 2.5 times more likely to display the highest levels of fat mass. Those with televisions in their rooms were also three times more likely to have a high waist circumference and high triglyceride levels.

Triglycerides are a type of fat found in the body, which are associated with an increased risk of heart disease.

The scientists suggested that having a television in a child's bedroom ‘may create additional disruptions to healthy habits, above and beyond regular TV viewing'.

"For instance, having a bedroom TV is related to lower amounts of sleep and lower prevalence of regular family meals, independent of total TV viewing time. Both short sleep duration and lack of regular family meals have been related to weight gain and obesity," they explained.

Details of these findings are published in the American Journal of Preventive Medicine.