A simple formula can predict -- much more accurately than complicated genetic tests -- whether a baby is likely to become obese in childhood, a new study claims.

The formula, which is available as an online calculator (http://files-good.ibl.fr/childhood-obesity), estimates the child's obesity risk based on a handful a of key risk factors:

  • birth weight
  • body mass index of the parents
  • number of people in the household
  • the mother's professional status
  • the mother’s smoking status during pregnancy

The researchers behind the study, who have published their findings in the online journal PLOS ONE, hope their calculator can be used to spot infants at high risk and help their families prevent their children from putting on too much weight.

The researchers came up with their calculator during a study that followed 4,000 children born in Finland.

The team had planned to look at whether obesity risk could be estimated by looking at the genetic profiles of the children to test for common genetic variations. But the test they developed failed to make accurate predictions.

Instead, they looked at information readily available at the time of birth, and found that those factors were more accurate at predicting obesity risk. The formula worked not just in Finnish kids, but in further tests using data from studies in Italy and the U.S.

The study’s lead author, Prof. Philippe Froguel, from the School of Public Health at Imperial College London, notes that all the points they looked for were well-known risk factors for childhood obesity.

“But this is the first time they have been used together to predict from the time of birth the likelihood of a child becoming obese,” Froguel said in a statement

He says the beauty of the study is its simplicity. "This test takes very little time, it doesn't require any lab tests and it doesn't cost anything."

The researchers suggest that dieticians and physicians could use the test results to better target help children at high risk of obesity.

"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," Froguel noted.

Not all children who have the risk factors are destined to become obese, the research team notes.

By the same token, they also say about one in 10 cases of obesity are caused by rare genetic mutations that seriously affect appetite regulation.