Exercise is one of the most universally recommended activities for improving health, but its true impact on our bodies and brains might be far more profound than we realize.
A fascinating new study from the University of Jyväskylä in Finland, known as FITFATTWIN, suggests that even identical twins—who share the same genetics and upbringing—can have drastically different physical and mental outcomes depending on how much exercise they engage in as adults.
This groundbreaking research reveals that a few years of different exercise routines can reshape not only the body but also the structure of the brain.
The results provide compelling evidence of how exercise influences both cardiovascular health and cognitive function, potentially challenging long-held assumptions about fitness, genetics, and destiny.
The Surprising Link Between Physical Activity and Brain Health
The study’s findings are as simple as they are powerful: the more active twin had better cardiovascular health, higher levels of grey matter in the brain, and superior motor control and coordination compared to their less active sibling.
But it’s the implications of this discovery that are truly astonishing.
For years, we’ve known that regular physical activity offers a wealth of health benefits: reduced body fat, enhanced cognitive function, and protection against chronic conditions like diabetes and heart disease.
What’s less clear, however, is how significantly exercise can reshape the brain—and how rapidly this transformation can occur.
Through the study of identical twins, the researchers from Finland were able to isolate the influence of lifestyle choices, free from the confounding variables of genetics and upbringing.
And the results are striking.
Exercise doesn’t just help improve physical health—it can literally change the structure of the brain in ways that have long-lasting effects on motor function, memory, and overall cognitive abilities.
The Study: A Deep Dive into the Impact of Exercise
The FITFATTWIN study was no small feat.
The researchers focused on 10 pairs of identical male twins in their early 30s, all from Finland.
These twins were ideal candidates because they shared exactly the same genetic material and had been raised in similar environments, making them a perfect control group for the researchers.
The crucial difference was that some of the twins had maintained an active lifestyle while others had become more sedentary, often due to work or family commitments.
The researchers took a variety of measurements to assess the physical and cognitive differences between the pairs.
These included height, weight, body fat, blood samples to assess insulin sensitivity, and brain scans to examine the structure of the brain.
The results were clear: even subtle changes in physical activity can have an outsized impact on both physical health and mental performance.
The more active twins were fitter, had better insulin sensitivity, and were less likely to develop chronic diseases such as diabetes.
But it wasn’t just their bodies that were healthier; the more active twins also exhibited greater grey matter density in key areas of the brain, such as the striatum and prefrontal cortex—regions crucial for motor control, decision-making, and higher cognitive functions.
What Makes This Study So Groundbreaking?
The significance of this study lies not just in the findings themselves, but in the methodology that allowed the researchers to draw such clear conclusions.
Long-term randomized controlled studies on exercise are notoriously difficult to conduct due to the complex and multifaceted nature of exercise habits.
Factors like genetics, upbringing, diet, and environmental influences make it nearly impossible to account for all the variables that affect health outcomes.
Instead of trying to control for these variables, the researchers took a different approach: they focused on identical twins, whose genetic makeup is identical.
By studying twins who had diverged in their exercise habits over just a few years, the researchers were able to isolate the effects of physical activity on health.
This allowed them to show that the differences in health outcomes between the twins were likely due to their differing exercise routines—and not to genetics or upbringing.
As Dr. Urho Kujala, one of the study’s authors, explained to Gretchen Reynolds at The New York Times:
“All of these differences in the young men’s bodies and brains had developed during their few, brief years of divergent workouts, underscoring how rapidly and robustly exercising—or not—can affect health.”
In other words, even relatively short-term changes in physical activity can have an outsized impact on both physical fitness and brain structure.
Challenging the Assumption: Genes and Environment Don’t Dictate Our Health
For many of us, the idea that genes and environment are responsible for our health outcomes has become a deeply ingrained belief.
After all, how many times have we heard that “I’m just built this way” or that “my family has a history of health problems”?
The message is clear: our bodies and brains are shaped by our genetics and the environment in which we grew up.
But this study flips that narrative.
It suggests that genetics and upbringing don’t have to dictate your health or fitness destiny.
In fact, adopting a more active lifestyle—even later in life—can dramatically reshape your body and brain in ways that were once thought to be impossible.
While it’s true that genes can influence things like metabolism, muscle mass, and fat storage, the study underscores the remarkable plasticity of both our bodies and our brains.
Exercise is a powerful tool that can overcome genetic predispositions and environmental barriers, offering an opportunity for virtually anyone to improve their health and well-being.
In essence, your habits may matter just as much—if not more—than your genetics.
How Can You Use This Information to Improve Your Life?
The implications of this research are profound: if exercise can have such a powerful impact on the body and brain, why aren’t more of us making it a priority in our daily lives?
It’s easy to think that exercise is something we’ll get around to eventually—when we have more time, when we’re less tired, when work isn’t so demanding.
But the truth is, even small changes can have a lasting impact.
Here are a few takeaways from the study:
- Start small: Even modest increases in physical activity—like taking the stairs instead of the elevator or walking for 20 minutes each day—can lead to significant improvements in health over time.
- Make exercise a part of your routine: It doesn’t have to be an intense workout at the gym; consistency is key. Find an activity you enjoy and make it a regular part of your day.
- Be patient: The changes that happen in your body and brain won’t be immediate, but the study shows that positive changes can occur much faster than most people realize.
- Focus on both the body and brain: Exercise isn’t just about looking good—it’s about feeling good mentally and emotionally as well. Regular physical activity has been shown to improve mood, reduce stress, and sharpen cognitive function.
Conclusion: The Power of Exercise
This study is a reminder of the incredible power that exercise holds—not just for our bodies, but for our minds as well.
It’s easy to get caught up in the idea that our health is predetermined by our genetics or our past experiences.
But the FITFATTWIN study shows that the habits we cultivate today have the power to shape our bodies and brains for the better, no matter what our genetic makeup or environment might suggest.
So, the next time you’re thinking about skipping your workout or putting off your fitness goals, remember this study: even a few years of regular physical activity can make a world of difference.
And the best part?
It’s never too late to start.
Source: The New York Times, Medicine and Science in Sports and Exercise
