London, May 20 (IANS): Do your children go to school walking or riding a bicycle? If your anser is in affirmative, then they are less likely to be obese than those who use car or public transport, suggests a new study.

The study's findings suggested children who actively commuted to school had lower body fat and were less likely to be overweight or obese.

In the study, published in the BMC Public Health journal, the researchers assessed the impact of extra-curricular physical activities -- daily commuting to school and participation in sports -- on overweight and obesity levels among primary school children.

The researchers observed that physical activity was better predictor of obesity level in children than commonly-used body-mass index (BMI) as it looked at total weight, including "healthy" muscle mass, rather than fat mass alone.

"Both BMI itself and the points at which high BMI is associated with poor health vary with age, sex and ethnicity," said the study's first author Lander Bosch, a Ph.D scholar at University of Cambridge.

"While adjustments have been made in recent years to account for these variations, BMI remains a flawed way to measure the health risks associated with obesity," Bosch said.

For the study, the researchers included over 2,000 primary school children.

Likewise, the researchers also used BMI to check obesity risk in children. Surprisingly, children who participated in sports daily appeared more likely to be overweight compared with those who engaged in sports less than once a week.

"The link between frequent participation in sport and obesity levels has generated inconsistent findings in previous research, but many of these studies were looking at BMI only," asserted Bosch.

"However, when looking at body fat instead, we showed there was a trend whereby children who were not active were more likely to be overweight or obese. It's likely that when looking at the BMI, some inactive children aren't classified as obese due to reduced muscle mass," he noted.

The researchers maintained that active commuting to school could be "promising" for combating childhood obesity. "It's something so easy to implement and it makes such a big difference," said Bosch.