A novel study on twins removes doubt about the role exercise plays in our body fat and fitness level
Hard work can only get you so far—at least, that's what science has been telling us for years. The more you work out, the fitter and healthier you'll be of course, but researchers have actually had a hard time proving that exercise is directly causing these long-term changes in our bodies and brain. Because of so many variables, like genetics and upbringing, the closest they can come is proving association—or the idea that people who exercise tend to be healthier, not that exercises causes healthy changes.
But thanks to a loophole in variables, Finnish researchers have come closer than ever before in proving that exercise has a direct impact on our physical and mental health exclusive of all environmental, dietary, and genetic factors. The exception they found? Identical twins.
By definition, twins have the same DNA and, assuming they were raised together, the same habits from their upbringing. Scientists at the University of Jyvaskyla looked at identical twins in their early adulthood who had taken up drastically different exercise habits after leaving their childhood home. (Interestingly, this was hard to find—most pairs in the Finnish twin database shared similar exercise routines still, despite living apart.)
The results? Genetics were pretty much the only identical factor left between the two. For starters, the inactive twins had lower endurance capacities, or your body's ability to work hard for a long time. The sedentary siblings also had higher body fat percentages (despite the similar diet) and showed signs of insulin resistance, meaning pre-diabetes may be in their near futures. (Check out these other 3 Bad Habits That’ll Ruin Your Future Health.)
And the differences went beyond just the physical: The inactive twin also had significantly less grey matter (brain tissue that helps you process information) than their sweat-loving sibling. This was especially prominent in the brain areas involved in motor control, meaning their muscle coordination was inferior to their fit family member's.
Since the pairs had identical genetics and similar habits until only a few years ago, these findings suggest that exercise can significantly affect your body, health, and brain in a relatively short period of time.
Additionally—and perhaps more importantly for some—the differences between active and inactive twins also suggest that genes don’t have the final say in how fit you’re destined to be, said study author Urho Kujala. (Are Parents to Blame For Your Bad Workout Habits?) That's right, science has proven that all potential is in your own hands—so get going!