A study of over 12,000 men and women reveals that a brisk daily walk can change how the DNA your mother and father gave you affects your body, particularly the 32 genes that have been linked to a person’s body mass index, or BMI, a ratio of height and weight used to determine if someone is obese. After indexing how many variants of the weight-gain genes each person in the study had, researchers at the Harvard School of Public Health concluded that “for every genetic variant, the effect on BMI was to increase it by 0.13 kg/m2.”
What’s the Big Idea?
Exercising, however, defined by the study as briskly walking for one hour per day, reduced the genetic effect of the weight-gain genes by 50 percent to 0.06 kg/m2. The study is the first of its kind to examine how exercise alters the behavior of genes. It also found that sedentary behavior, such as watching TV for several hours, had an independent effect on genes, intensifying their influence over weight-gain. Thus the study’s authors recommend increased physical exercise and reduced sedentary behavior as a way to counteract genes which predispose us to obesity.