Body Composition: Nature or Nurture?
February 16, 2021
Ever wondered how much your genetics affect your health? Your DNA can have a surprisingly large effect on your body composition and your risk of chronic illness.
It’s no surprise that your genetics can play a huge role in not only your body shape, appearance, and body composition, but also your health and your risk for certain chronic illnesses.
However, even if you think you have “bad genes,” this is no reason to feel hopeless. When it comes down to it, you can still take charge of your health, no matter your DNA.
By pairing healthy lifestyle changes with health monitoring methods—like DEXA (DXA) scans to measure your body composition, checking blood biomarkers, and monitoring your resting metabolic rate (RMR)—you can overcome your genetic disadvantages.
Genetics and body composition
If you’ve ever noticed that, for the most part, families tend to have similar body types and sizes, then you understand how drastically genetics can affect body composition. In addition to the genes you inherit from your parents, your genetic health advantages or disadvantages can actually also be shaped by your mother’s overall health (and even her diet) while she was pregnant with you.
Research shows that babies born to women who ate more fat and carbs during their pregnancy had more body fat than those born to women who ate extra protein—regardless of the mother’s size when she became pregnant.
Additionally, twin studies can give us some unique insights into the “nature versus nurture” argument when it comes to body composition and genetics. Twin studies are performed by observing twin siblings—mostly identical—and comparing and contrasting a number of factors in order to assess the degree to which genetics influence those factors.
According to some twin studies, genetics account for up to 90% of the variability in your body mass index (BMI). However, we know that BMI can be an incomplete picture of your health if you don’t also know your body composition numbers—like fat mass and fat-free mass. Even still, one interesting study in 30 pairs of adult twins found that genetics had a stronger effect on body composition than any of the following factors: age, gender, number of children, activity level, and whether or not they were a smoker.
These surprising results highlight just how powerfully your genetics can affect your body composition, which in turn can dictate your health. One of the most important aspects to consider is how your genetics may impact your body fat, where you carry it, and the types of fat that you carry.
Genetics and fat storage
Whether or not you’re obese—or carrying an excess of body fat—is thought to be a genetic response to environmental factors, like your diet. According to emerging research, certain people are genetically predisposed to obesity.
This is known as the “thrifty genes” concept. Genetically, a large subset of the population is predisposed to store fat and resist fat loss. In the past, this would have been an advantage because it decreased your risk of starvation if you had adequate fat stores, but in our modern environment this makes it extremely easy to reach an unhealthy level of body fat.
Genetics can also influence your body type, or where on your body you tend to store fat. A gynoid fat distribution involves fat storage in the hips, buttocks, and thighs, while android fat distribution is characterized by abdominal fat.
And unfortunately, those with primarily android fat distribution patterns are more likely to carry visceral fat, or fat that lines their organs and concentrates in the abdomen. Compared to the subcutaneous fat (fat underneath the skin) that is predominant in gynoid body types, visceral fat can increase your risk of chronic illnesses like heart disease and type 2 diabetes.
Finally, your genetics can also dictate how much brown fat you have. Compared to white fat, which is biologically inert, brown fat activates under certain conditions (like cold temperatures) to warm you up. It does this by burning white fat, so there are some advantages to having larger brown fat stores.
Although most people lose the majority of their brown fat stores during early childhood, the amount of brown fat you have remaining into your adulthood may be dictated by your genetics.
So, can anything be done if you may have a genetic disadvantage that predisposes you to excess or unhealthy fat storage?
Overcoming “bad genes”
Genetics are just one part of the equation. Having family members with chronic illnesses or “bad genes” is definitely no reason to feel like bad health is inevitable. In fact, you can use that fact as the motivation to lead a healthy lifestyle, assess your risk factors regularly, and stay on top of your health.
Here are three ways you can cultivate good health, no matter what your genetic history is:
Eat a balanced diet. A healthy diet is key to avoiding unwanted weight gain—which unfortunately tends to be visceral fat. Eat plenty of fruits and vegetables, choose whole grains and protein-rich foods, and try to avoid excess sugar and highly processed foods.
Exercise regularly. Cardio exercise can help increase your bone density, reducing your risk of osteoporosis. It can also help with weight loss efforts if you’re trying to lose body fat. Additionally, strength training—like lifting weights or doing bodyweight exercises—can increase your muscle mass and metabolic rate, or the amount of calories you burn at rest.
Monitor your body composition. A DEXA scan can give you a baseline of your fat mass and fat-free mass, and you can then measure it against where you need to be on a body composition chart. As you make changes to your lifestyle habits, you can repeat the scan every few months to monitor your progress.
Although genetics play a huge role in body composition, having “bad genes” is no reason to be discouraged about your health. It’s empowering to know that the choices you make can have just as much influence on your overall wellness, and a healthy body composition, as your genetics.
Leading a healthy lifestyle can help balance out whatever genetic predispositions to poor health you may have, and Fitnescity is here to support you any way we can—be it DEXA scans, metabolic rate testing, or blood biomarker testing. If you’re ready for a healthy lifestyle change, get started with us today.
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