The millions of people whose genes make them
prone to obesity aren’t at the mercy of nature. How they choose to spend their
free time can make a big difference in their waistline, according to new
research from the American Heart Association (AHA) meeting in San Diego.
Watching TV for two hours each day increases
the effect of certain obesity-related genes by as much as 25%, the researchers
estimate. If, on the other hand, people with a strong genetic predisposition to
obesity spend one hour each day walking briskly or engaging in comparable
exercise, they can halve the genes’ effect.
The influence of the gene variants, however,
appeared to be strongest in people who watched the most TV. The variants’
effect on BMI was about four times greater in people who spent 40 hours or more
per week in front of the TV than it was in those who watched an hour per week
or less.
Prolonged TV watching exacerbates the effect
of the gene.
By the same token, weakening the genes’ effect
was as simple as switching off the television and going for a brisk walk. The
average difference in BMI between a person with the highest genetic obesity
risk and a person of identical height with the lowest risk would be cut in half
if the high-risk person were to walk for an hour each day.