Azara Blog: First evidence of a genetic component to obesity

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Date published: 2007/04/13

The BBC says:

Scientists say they have identified the clearest genetic link to obesity yet.

They found people with two copies of a "fat" version of a gene had a 70% higher risk of obesity than those with none, and weighed 3kg (6.5lb) more.

The work in Science by the Peninsula Medical School and Oxford University studied data from about 40,000 people.

The findings suggest that although improving lifestyle is key to reducing obesity, some people may find it harder to lose weight because of their genes.

Half of white Europeans carry one copy of the variant and one in six has two copies, experts estimate.
People carrying one copy of the "fat" FTO variant had a 30% increased risk of being obese compared to a person with no copies of that version.

Those carrying two copies of the variant had a 70% increased risk of being obese, and were on average 3kg (6.6lb) heavier than a similar person with no copies.

Professor Andrew Hattersley of the Peninsula Medical School said this could explain why two people can seem to eat the same things and do the same amount of exercise yet one may struggle to lose weight more than the other.

He said: "The typical message has been that if you are overweight it is due to sloth and gluttony and it is your fault.

"This work is suggesting that there is also a genetic component."

And he said although a 3kg difference in weight sounds relatively small, it is enough to make a big change in the risks of obesity.

So far all we have is a correlation, not a causation although here it seems likely that these genes must play some role in obesity, perhaps in concert with other genes. Until there is an understood molecular mechanism, rather than just a correlation, the science is not resolved. Of course everybody always thought there was a genetic component to obesity, but environmental factors, in particular diet, pretty clearly play a bigger role. (People today are on average a lot fatter than they were thirty years ago, but the gene pool has not changed that much.) So this study is not nearly as remarkable in consequence as some in the media would have you believe.

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