The researchers found that by the age of seven, around one in four girls have weight issues compared with just one in six boys.
Experts theorize that more sedentary lives in front of televisions and computers, less physical activity, and too much pampering from parents may be responsible for girls being fatter than their male counterparts.
Lead author of the study, Dr Alice Sullivan stated, "Girls and only children are more likely to become overweight between the ages of five and seven. It is not clear whether the increased risk for girls is due to them being over-fed compared to boys, or because they are involved in less physical activity – perhaps due to the over-protectiveness of parents – or some combination of the two.
"Similarly, we do not know whether only children are less active due to lack of siblings, or over-fed by indulgent parents.
"Either way, making parents aware of the increased risk to girls and only children may help to modify their behaviour."
Changes in kids' weight in first 7 years of life traced
A study conducted by the Institute of Education, which is part of the University of London, traced the changes in children’s weight over the first seven years of their life.
The researchers analyzed the body weights of 11,000 children, born between 2000 and 2002, who were part of the Millennium Cohort Study.
Revelations of the study
The investigators found that apart from gender, the number of siblings a kid had also pointed towards weight problems.
It was noted that seven-year-olds without brothers and sisters were 25 percent more inclined to be overweight than those with one sibling.
Also, the odds of obesity in an only child rose by 30 percent compared to those with two siblings.
The study also found that kids who were heavier by five years were 25 times more likely to have weight problems at age seven as opposed to children of normal weight.
Another interesting aspect of the study was that kids whose parents were obese or inclined to smoke were also likely to be overweight.
The researchers stated, “The importance of parents’, and especially mothers’ BMI, suggests that overweight is a family problem, and health messages need to be targeted at mothers in particular.
“Childhood overweight appears to be primarily due to an obesogenic home environment rather than individual child level factors.”