If you’re frustrated by the inability to change the shape of your body, don’t be too quick to blame your genes or feel defeated by them. According to a fascinating study carried out by researchers in Finland, exercise gives you a “leg up” on genetics and helps you stay slimmer and healthier from a metabolic standpoint.
Genetics versus Lifestyle: A New Approach
Most studies looking at genes versus lifestyle and their impact on health use diet and exercise questionnaires and are carried out on people with different genes, so you’re not comparing apples with apples due to the influence of genetics. What if you could study the effects of exercise and lifestyle habits on people with the very same genes? In this case, we’re speaking of identical twins. If you compare twins with the same DNA, but different exercise habits, you get a better idea of how much impact lifestyle really has on body composition and overall health. That’s exactly what researchers in Finland did.
The reason more studies like this aren’t done is that it’s hard to find twins who have lifestyle and exercise habits that greatly differ from one another. After all, in most cases, twins grow up in the same environment, and, of course, they have the same genetics, therefore they’re likely to have many of the same habits. To overcome this obstacle, Finnish researchers used a large countrywide database and identified 17 groups of male identical twins in their 30s who had dissimilar exercise habits. In most cases, one of the two identical twins had stopped exercising in the past few years due to time issues that made it difficult for them to work out. Twins who had physical illnesses that precluded them from exercising were excluded from the study as were those who had only recently changed their exercise habits.
To compare the twins, researchers measured various markers for health and fitness. Identical twins would be expected to have similar aerobic or endurance capacity based on similar genetics, but when they measured each twin’s endurance capacity, as you might expect, the exercising twin had superior aerobic endurance. No surprise here. Twins who differed in exercise habits also had contrasting body fat percentages, with the exercising twin of the pair carrying less total body fat. Interestingly, the twin pairs didn’t differ in lean body mass percentage, which was also not surprising since the form of activity the twins mainly participated in was aerobic, not resistance-based exercise.
The exercising twins also had healthier metabolic profiles. When they used tests that measured insulin response, the active twins had better insulin sensitivity than their inactive sibling. Insulin sensitivity is an indicator of metabolic health. Poor insulin sensitivity is strongly linked with type 2 diabetes and a greater risk of heart disease and obesity. What’s also interesting: the brains of the identical twins differed from one another. The active twins had larger basal ganglia volume, a characteristic linked with a reduced risk for metabolic syndrome. In addition, portions of the brain that coordinate physical movements were more robust in the exercising twins. The brains of the more active of the twins had actually been changed by exercise. Amazing, isn’t it?
The Profound Effects of Exercise on Health
Though this was a small study, it illustrates the potential exercise has to modify the expression of genes you feel like you’re stuck with. In some studies, it’s hard to remove out the impact of environment versus genes, but this small study does it in a convincing way – by using identical twins. Despite being dealt similar genetic hands, exercising twins had distinct health advantages – a lower percentage of body fat, better insulin sensitivity and a reduced risk for metabolic syndrome, which all bode well for future health. Most importantly, you can’t say it’s because they were genetically blessed because their identical twin fared less well.
Also fascinating is the way exercise remodeled the brains of the more active twins, especially portions of the brain associated with metabolic health and coordination of movements. The twins in this study may have looked identical on the outside, but inside their brains, looked not so similar. Although not seen in this study, a number of research studies show people who do aerobic exercise have a larger hippocampus, a portion of the brain involved in memory and cognitive processing.
Exercise Your Way to Brain Health?
One study showed aerobic exercise increased hippocampal volume by 2%. This degree of change doesn’t sound like a lot, but it’s significant when it comes to cognitive function. Another study found aerobic exercise boosted hippocampal volume in older women with mild cognitive impairment, a condition marked by memory problems that aren’t as severe as what people with Alzheimer’s experience. Research even shows hippocampal volume is linked with levels of physical activity, even in young and middle-aged men and women. In animals, physical activity actually promotes the growth of new nerve cells and expands the complexity of existing ones. Build a better brain through exercise!
The Bottom Line?
Don’t let your genetics define you. As the field of epigenetics shows, lifestyle habits affect how genes are expressed. Even if you’re at high risk for obesity, heart disease or metabolic problems like type 2 diabetes, exercise helps to counteract the effects of “bad genes.” Although this study didn’t look at resistance training, it too is essential for healthy aging. Working your body against resistance helps you hang onto lean body mass, maintain functionality and keep your bones strong and healthy. No matter what your genetics, exercise can improve your health and change how you look and feel. Take advantage of it!
References:
Med Sci Sports Exerc. 2015;47(3):509-518.
Medscape Family Medicine. “Physical Activity, Fitness, Glucose Homeostasis, and Brain Morphology in Twins”
PNAS. “Exercise training increases size of hippocampus and improves memory” December 30, 2010.
Br J Sports Med doi:10.1136/bjsports-2013-093184.
Scientific Reports 3, Article number: 3457 doi:10.1038/srep03457.
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