Exercise 'blunts fat gene effect'

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Vigorous physical activity could blunt the effects of a common gene linked to obesity, claim US researchers.

Carrying two copies of the FTO gene significantly increases the chances of becoming obese.

However, a study carried out among the US Amish community found an active lifestyle appeared to remove this risk.

A UK specialist said the results, reported in the Archives of Internal Medicine journal, would be interesting if repeated by larger studies.

Some of the genes shown to cause obesity in our modern environment may not have had this effect a few centuries ago when most people's lives were similar to that of present-day Amish farmers Dr Soren SnitkerUniversity of Maryland <a class="" href="/1/hi/health/5297790.stm">Calculate your BMI</a>

The complex relationships between our genes and lifestyles, which can mean obesity for some people and not for others, has yet to be fully understood.

Several genetic variants have been linked to obesity, but none is wholly responsible for it.

The most common of these is FTO, with half of all people in Europe carrying either one or two copies of it.

It is not clear how it influences weight gain, although some scientists have suggested it may play a role in an individual's appetite.

The study from the University of Maryland supports other research which suggests that a person's level of exercise may help determine whether their genetic makeup will contribute to obesity.

Movement log

The researchers looked at 704 Amish men and women, chosen because of that community's relative genetic "purity", with members generally able to trace their ancestry back for 14 generations to early settlers from Europe.

Volunteers were fitted with "accelerometers", measuring their precise movements over a period of time.

They found that while the expected link between the number of copies of FTO carried and increased body mass index could be seen in less active volunteers, that link was broken once in those who recorded high levels of activity - equivalent to three to four hours of moderately intensive activity.

Dr Soren Snitker, who led the research, said: "Our results strongly suggest that the increased risk of obesity due to genetic susceptibility can be blunted through physical activity.

"Some of the genes shown to cause obesity in our modern environment may not have had this effect a few centuries ago when most people's lives were similar to that of present-day Amish farmers."

Professor Andrew Hattersley, from Peninsula Medical School in Devon, who also carries out research into the FTO gene, said that this was the second study which suggested that exercise levels could have a bearing on the way this gene had an effect on obesity.

"Because the gene effects are very small, it would be good to see this repeated in larger studies.

"The weight of evidence for physical activity potentially overcoming genetic susceptibility is increasing."