Too many people think their genes prevent them from losing weight. Yet studies show lifestyle plays a bigger role in controlling body weight than genes. But that doesn’t mean genes are off the hook! Scientists have found at least five types of genes that affect body weight. There’s good news, though. Making lifestyle changes can help you lose weight even if you inherited a “bad” version of these genes. Let’s take a look at five ways genes affect your weight.
Genes that Control Resting Metabolic Rate
Your resting metabolic rate is how many calories you burn when you aren’t exercising and haven’t eaten recently. There’s a genetic component to resting metabolic rate. Maybe you know someone who eats whatever they want and doesn’t gain weight. There might have been other family members who could do the same. People with higher resting metabolic rates may have genes that boost their resting metabolic rate. Other factors like age, gender, and how much muscle you have on your frame affect your resting metabolism too, but the speed with which your body burns energy does have a genetic component.
Genes that Affect Leptin Signaling
There’s a hormone called leptin that decreases appetite and increases resting metabolic rate. Your leptin levels rise after a meal, which makes you feel full and signals your body burn fat. You can think of leptin as one of the hormones that keeps you from overeating. In fact, there’s a rare genetic disorder that causes obesity and a voracious appetite in affected people.
Most people produce leptin, but there are variations in receptor sensitivity to leptin based on genetics. Some people have leptin receptors that are shaped differently and don’t respond as well to the appetite-calming effects of leptin. As you might expect, this increases the risk of obesity since it leads to a stronger appetite and a slower resting metabolic rate.
Genes that Control Insulin Sensitivity
How sensitive your cells are to insulin directly affects your metabolic health and your odds of obesity. If you have low insulin sensitivity, or insulin resistance, your pancreas must produce more insulin. In addition, the insulin hangs around longer, and that increases how readily your body stores fat. Obesity causes insulin sensitivity to go down, which makes losing weight harder. Insulin resistance has a genetic component too. PTP-1B is a gene that controls insulin activity and has a variant that worsens insulin resistance.
Fortunately, you can improve insulin sensitivity, even if genetics work against you, through exercise, both aerobic and strength training. For people who are genetically prone toward low insulin sensitivity, exercise and an active lifestyle can make all the difference.
Genes that Regulate Uncoupling Proteins
People who are leaner have higher levels of uncoupling proteins in a type of fat called brown fat. Brown fat is a type of inefficient fat that generates heat. Babies have more brown fat than adults since they use the breakdown of brown fat to stay warm. But adults keep some brown fat on their body throughout life, usually around the neck and shoulders.
People who are lean and can eat a lot and not gain weight are better at harnessing brown fat because they have different levels of uncoupling proteins. This gives them an advantage metabolically. The best way to turn on brown fat is to live and work in a cooler environment with a temperature of 60 degrees F. and lower. Some scientists think obesity is on the rise because people work in warmer environments now.
Genes that Affect Circadian Rhythms
Circadian rhythms are natural cadences that tell your body when to release certain hormones and factors that affect many functions in your body, including appetite, metabolism, and body weight. Your internal biological clock in your brain sets your circadian rhythms and keeps them synchronized.
These rhythms control factors like your sleep-wake cycle, appetite, insulin sensitivity, mood, and more by altering the release of hormones. Shifts in the circadian clock can alter appetite and affect hormones that influence body weight. For example, circadian rhythms affect the release of hormones like leptin and ghrelin that control appetite and insulin.
Think your circadian rhythms are off kilter? How you live and eat matters. You can shift your internal biological clock through lifestyle, such as by changing your sleeping schedule, but there’s also a genetic component to the circadian clock and rhythms. For example, some people have a genetic variant of the biological clock that makes it easier to gain weight. This variant causes a more profound drop in resting metabolic rate with dieting. Having this variant makes it harder to lose weight.
How can you optimize your internal biological clock? Maintaining a regular sleep schedule and going to bed as soon as it gets dark is beneficial while staying up late, working night shifts, and not exposing your eyes to light during the day will negatively affect your sleep and your circadian rhythms. Also, eating earlier in the day and not snacking at night helps set your biological clock in a healthy way, and may help with weight loss Making this adjustment may also lower the risk of type 2 diabetes, cardiovascular disease, and even some forms of cancer.
The Bottom Line
Now you know some genes that make it easier or harder to lose weight. However, lifestyle plays the biggest role in how much you weigh. Even if you have genetic factors working against you, dietary, exercise, and sleep habits can change the expression of these genes. So, don’t get bogged down with the genetic hand life dealt you, but immerse yourself in leading a healthy lifestyle instead. You can’t change your genes, but you can alter your lifestyle in a positive way.
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- Int J Obes (Lond). 2014 Aug;38(8):1083-8. doi: 10.1038/ijo.2013.211. Epub 2013 Nov 15.
- Dis Model Mech. 2017 Jun 1; 10(6): 679–689.doi: 10.1242/dmm.026609.
- “What Is Brown Fat? – WebMD.” https://www.webmd.com/diet/brown-fat-what-you-need-to-know.
- “How is brown fat different from other fat? – Mayo Clinic.” 05 Nov. 2020, https://www.mayoclinic.org/healthy-lifestyle/weight-loss/expert-answers/brown-fat/faq-20058388.
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