Lead researcher Professor Philippe Froguel said: "Once a young child becomes obese, it's difficult for them to lose weight, so prevention is the best strategy and it has to begin as early as possible.
"Unfortunately, public prevention campaigns have been rather ineffective at preventing obesity in school-age children.
"Teaching parents about the dangers of over-feeding and bad nutritional habits at a young age would be much more effective."
Prof Froguel's team whittled dozens of factors linked to obesity down to six pointers which they claim, taken together, provides an accurate prediction of risk.
First you are asked for the mother's and father's body mass index - a measure of weight in comparison to height. It's thought children of overweight adults are more likely to become fat themselves because they learn bad habits from their parents.
The calculator then asks for the number of people in the household. Studies have shown children from single-parent families have higher odds of obesity, perhaps because the parent has less time to spare in looking after them.
The fourth question asks for the mother's professional status and the fifth asks whether the mother smoked in pregnancy. While babies of smokers can be lighter when they are born, they tend to pack on the kilos later.
Finally, the baby's weight at birth is tapped in.
Large-scale testing of the calculator on children in Finland, Italy and the US showed it to be quick and accurate. It also emerged that including genetic information provided little extra benefit.
Researcher, Professor Marjo-Riitta Jarvelin, said that the calculations could be carried out on newborns or at clinics when babies are being weighed and monitored.
Parents with children at high risk of obesity could then be given extra information on healthy eating and exercise.
Writing in the journal PLoS ONE, the researchers said parents could also be advised about breastfeeding, which is thought to reduce the risk of a baby growing up to become obese, avoiding TV and not giving their children soft drink.
Prof Jarvelin said: : "One of the key issues is how much children sit in front of their computers rather than interacting or playing with other children."
- DAILY MAIL
