This is in contrary to the popular belief that kids in the lower income have poor diet pattern thus there is a higher risk of obesity among them. But it is now seen that the risk of obesity actually soars with family income.
The study also highlighted the fact that middle-class mothers who work long hours increase the risk of their offspring being overweight or obese. The highly-paid working mothers are often forced to leave a nanny or nursery in charge of their child's diet and physical exercise.
"Long hours of maternal employment, rather than lack of money, may impede young children's access to healthy foods and physical activity," say the researchers from the Institute of Child Health at University College London (UCL) and Great Ormond Street Hospital (Gosh), writing in the International Journal of Obesity this week.
The study, published in the International Journal of Obesity, revealed that children from families with an income between £22,000 and £33,000 were 10 per cent more likely to be overweight or obese than those from families with an income of less than £11,000. Where the family income was £33,000 or more, children were 15 per cent more likely to be overweight than the poorest children.
In family with high income and where working mother is absent from the scene there is a high consumption of snack foods and sweetened aerated drinks. There is also not much of physical activity involved as majority of the time is spent in front of the television. These factors mainly contribute to obesity. Among the working mothers there is low rate breast feeding.
It is seen that children in childcare are 24 per cent more likely to be overweight or obese than children cared for by their mother or her partner.
Health experts said the results were a warning to middle class families who often "assumed" their children were living healthy lives.
Dr Susan Jebb, head of nutrition and health at the Medical Research Council Human Nutrition Research, said: "Obesity is something that affects middle class families as well, and that's important because many people take it to be an issue which only affects low income groups and it is absolutely not the case.
"This is a wake-up call for middle class families and it will hopefully get them to engage with the problem."
In school-age children, those whose mothers worked were less likely to eat healthily than those whose mothers were full-time homemakers.
Dr Colin Waine, chairman of the National Obesity Forum, said: "I do not want to condemn these women, but I do think the priority has to be the health of the child and its continued health into adulthood.
"We are in danger of raising a generation of young people with a much shorter life expectancy than previous generations.
"If women are working, there will be less time for food preparation and more resorting to convenience food. The types of food children are snacking on are going to be energy dense and there will be more sedentary hours than activity hours."
Ian Carter, programme director for Wellspring UK, a weight-loss camp for children and teenagers, says it is too simplistic just to blame working middle-class mothers for the crisis. "Obesity is a nationwide epidemic that affects people from all different backgrounds and is not just a middle-class issue affecting those with working mothers.
Dr Michele Elliott of Kidscape said: "The causative factor here has to be poor parenting regardless of whether you are working or not working."
A study by the Food Standards Agency found the food eaten by the poorest 15 per cent in society was little different from the average. The findings suggested poor eating choices were far more widespread than previously suspected, affecting many wealthy families.