Over half of inner-city schoolchildren could be eating fast food at least twice a week, a study suggests.
The research, carried out at two schools in the London Borough of Tower Hamlets, raises serious concerns over rising levels of childhood obesity in the UK as children indulge in heavy foods with a high fat content.
Published in the journal BMJ Open, the study assessed 193 pupils between the ages of 11 and 14, who were asked about their weekly food habits.
The pupils attended schools with an "open gate" policy during lunch periods. Although more than half of them were entitled to free school meals, they still chose to leave the school premises and purchase their own lunches from fast food outlets at least twice a week, while one in 10 did so every day.
Chips were the most popular option for the pupils. While girls were more likely to have just chips for their lunch, boys would buy larger portions, along with something more substantial, such as a burger or fried chicken.
One in three of the children in the study was either overweight or obese and those from non-white backgrounds were more likelyto frequent fast food outlets.
The study found seven out of 10 children from black ethnic backgrounds and more than half of those from Asian backgrounds ate fast food more than twice a week during school hours.
The researchers, from Newcastle University, said these findings were of additional concern, as people from these ethnic backgrounds are more prone to cardiovascular disease and diabetes.
The study looked into the children's reasoning behind their eating habits, in an effort to find a way that parents and teachers could educate them to make healthier choices.
In addition to highlighting the dangers of schools with an "open gate" policy during lunch periods, it was found that 71 percent of the children went to fast food outlets because they did not want to feel left out by their friends.
The majority of the children said more menu choices at school and cheaper prices would be the most effective means of keeping to them from leaving the premises over the lunch period.
"These children are exposed to an environment that is likely to cause obesity and it is not surprising that, in this situation, many of these children are already overweight or obese and will likely become obese as adults," the authors concluded.
"Clearly, actions need to be taken to either limit the ability of these children to access fast food outlets or to change what they purchase at these outlets."
The authors suggested that children consider less calorie dense dietary options, including more fruit and vegetables, with less intake of fat and salt.
As of December 2011, one third of all children in England were categorised as overweight or obese, with the figure continuing to increase.