A large UK study has concluded that our genes may determine as much as 77% of our obesity risk, while environmental factors seem to be less important.
Researchers from University College, London, assessed body mass index (BMI) and waist circumference in a sample of 5,092 twin pairs aged 8-11 years and born between 1994 and 1996. Studying twins is an accepted means of differentiating between inherited risk and the risk due to environmental influences such as diet or socioeconomic status. If genetic variation were the stronger predictor of obesity, monozygotic twins (identical genes) would have a greater obesity risk than dizygotic twins (non-identical genes) in the same environment.
Indeed, genetically identical twins were much more similar in terms of their BMI and waist circumference than non-identical twins, despite the sets of twins sharing the same home environment. Further analysis put the predictive value of inherited risk at ~77%, while shared environmental factors accounted for 10% and non-shared environmental factors for ~14%. This is in line with previous studies that had reported a genetic contribution of 55-85%.
The authors acknowledged that obesogenic environments were a risk factor but suggested that inherited predisposition remained a major reason why some children become obese and others do not. They recommended that diet, nutrition and physical activity be improved for all children to ensure that those with a genetic predisposition were less likely to gain excess weight.
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