‘Obesity may be largely genetic’

What did the media say?

The media reported that becoming overweight as a child was more likely to be the result of your genetic makeup than your lifestyle

What did the research show?

The researchers looked at 5,092 pairs of identical and non-identical twins, aged between eight and 11 years old. Non-identical twins have different genes, unlike identical twins, but are assumed to have similar diets during their upbringing.

The researchers used statistical modelling to look for associations between genetic make-up – for example the presence of the recently identified ‘obesity gene’ FTO – and body mass index and waist circumference.

They concluded that variations in children’s BMI and waist circumference were 77% attributable to genes and 23% attributable to the environment in which the children were growing up.

What did the researchers say?

Study author Jane Wardle, professor of health behaviour at University College London, said: ‘This study shows that it is wrong to place all the blame for a child’s excessive weight gain on the parents; it is more likely to be due to the child’s genetic susceptibility.

‘In today's environment – which provides unprecedented opportunities for all children to overeat and be sedentary – it is not surprising these tendencies result in weight gain,’ she added.

‘Targeting the family may be vital for obesity prevention in the earliest years, but longer-term weight control will require a combination of individual engagement and society-wide efforts to modify the environment, especially for children at high genetic risk,’ the authors said.

What does this mean for nursing practice?

A spokesperson for the National Obesity Forum said it feared the research would be misinterpreted as a reason not to bother about losing weight or striving for a healthy lifestyle.

‘The paper should not let anyone off the hook. On the contrary, the genetic predisposition to becoming overweight/obesity should re-emphasise the need to eat and exercise healthily,’ he said.

Dr Helen Wallace, director of science thinktank GeneWatch UK, added: ‘Twin study findings depend on the assumptions that are made about how genes and lifestyle interact. It is impossible to draw reliable conclusions about the importance of genetic effects from twin data alone.’

American Journal of Clinical Nutrition (2008) 87: 398-404

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