Researchers have created a genetic predisposition score that predicts obesity.

Using information collected on 2.1 million genetic variants, researchers at Massachusetts General Hospital and the Broad Institute of MIT and Harvard have created a genetic predisposition score for predicting whether a person will be obese. For a set of real people, those with scores in the highest 10% weigh, on average, nearly 30 pounds more than those with scores in the lowest 10%. In addition, people with the highest scores were 25 times more likely to have severe obesity (body mass index greater than 40) than those with the lowest scores. One important insight from the study is the fact that weight differences began to show up in children as young as three years old.

The scientists say these results confirm that genetics plays an important role in determining weight. Others argue the score does not account for lifestyle choices, which are a greater factor. While genetics account for approximately half of a person’s susceptibility to obesity, lifestyle choices can help overcome those tendencies and can therefore be more important. Because of this, trying to predict obesity just using genetic factors is not practical, they claim.

For instance, of 3722 people in one study group, only 58 of the 371 predicted to become obese did, and 171 of the 229 severely obese people were not identified as having a propensity towards obesity. Part of the problem is that less than 10% of the genetic variants that contribute to obesity were used to develop the score.

Despite the bluntness of the tool and the large error margin, one result of the study may be to reduce the stigma associated with obesity due to the fact that genetics is a significant contributor. In addition, people identified as having a high genetic risk for obesity might benefit from weight-control drugs.