Is Obesity Genetic?

Obesity rates in the United States are rapidly increasing. According to the Centers for Disease Control and Prevention (CDC), approximately 42% of adults live with obesity.

Several factors can play a role in your risk of developing obesity, such as environmental factors and systemic issues. However, genetics may also be why achieving or maintaining your body's ideal weight can be difficult. 

How Genetics Influences Obesity

Genetics can play a powerful role in developing many chronic conditions. However, how they do so isn't always straightforward. Researchers have investigated how genetics influences obesity through family and twin studies and have found that approximately 40-60% of obesity is influenced by genetics.

Genetics can increase your risk of obesity in three major ways—through monogenic, polygenic, or syndromic obesity.

Monogenic Obesity

Mono, or “one,” refers to obesity caused by a mutation in a specific gene. Most forms of monogenic obesity produce abnormal proteins such as leptin, which are important for appetite control.

People with monogenic obesity are typically diagnosed during childhood, which is why monogenic obesity is sometimes referred to as early-onset obesity. 

Polygenic Obesity

Researchers have developed new technologies to help scan the entire genome to better understand how different genes work together to influence your health. From their work, approximately 500 different obesity-related genes have been identified.

Polygenic obesity occurs when many different genes or small variations in genes (known as polymorphisms) influence your risk of developing obesity. It's a specific blend of polymorphisms that can influence aspects of your health, such as your eating behaviors or exercise levels.

When paired with an “obesogenic” environment, meaning living a sedentary lifestyle or eating high-calorie foods, this genetic combination can make it easier for you to develop obesity than someone who does not have these genetic mutations.

Syndromic Obesity

Syndromic obesity is usually early-onset (before age 5) and severe obesity. Children often have neurodevelopmental delays or dysmorphic features (physical abnormalities).

Syndromic obesity is associated with genetic conditions like Bardet-Biedle syndrome (BBS) and Alstrom syndrome.

How Environmental Factors Influence Obesity

For most people, obesity is not entirely genetic. Genetics, however, can set the stage for someone to develop obesity when paired with certain environmental factors.

An environment that makes it more likely for a person to develop obesity is called an “obesogenic” environment, which promotes less-than-ideal eating habits and physical inactivity. Some aspects of an obesogenic environment include:

• City planning that promotes car use versus walking 
• Poverty 
• Food deserts
• Increased screen time (e.g., TVs, computers, and video games)
• Living in areas with lower light exposure, such as in northern latitudes

Your environment can also affect your genes. Everyone is born with specific genes from their parents, but how these genes work can be influenced by your environment. For example, eating habits during early childhood can make small changes in your genes that make you predisposed to developing obesity later in life.

The development of new technology in this area, called epigenetics, has been helpful for researchers in predicting future obesity based on previous exposure to certain environmental factors. 

Risk Factors for Obesity

There are many different risk factors for developing obesity, many of which relate to one another. These factors include:

• Physical inactivity: Exercise is important for overall well-being, and living a sedentary lifestyle can increase your risk of developing obesity. 
• Diets high in calories, carbohydrates, and sugars: Regularly eating more calories per day than needed for your body can increase your risk of obesity, especially when not exercising as recommended. Eating foods high in sugars and carbohydrates can also cause insulin resistance, which makes it more difficult for your body to regulate your blood sugar and can increase your risk for type 2 diabetes and obesity.
• Maternal health: Smoking during pregnancy or living with obesity during pregnancy can increase the risk of your child developing obesity in the future.
• Underlying health conditions: Some health conditions, such as polycystic ovarian syndrome (PCOS), diabetes, depression, and hypothyroidism (underactive thyroid), can all increase your chances of developing obesity.
  

How To Prevent Obesity

Obesity can affect your overall health and well-being, increasing your risk of other health conditions, such as heart disease, diabetes, sleep apnea, and joint problems like arthritis. Obesity can also negatively affect your mental health, raising the risk of developing depression, anxiety, and low self-esteem.

Although your genetics may predispose you to developing obesity, there are several actions you can take to prevent unwanted weight gain. These include the following:

• Maintain a nutritious and balanced diet
• Get regular exercise
• Use techniques like yoga, meditation, and journaling to manage stress
• Sleep for at least seven hours per day

If you aren't able to manage a weight that you want for your body or are noticing symptoms of obesity, it can help to see your healthcare provider for support. They can help you understand why you're experiencing weight gain and what you can do to lower your risk of obesity and its related conditions.

When To Get Support

If you are concerned about your weight, talking with a healthcare provider is a great first step. They may refer you to other providers, such as a mental health professional, registered dietitian (RD), or registered dietitian nutritionist (RDN) to help develop the best weight management plan for you.

If you are not currently experiencing obesity but have a family history or a known genetic predisposition for obesity, your healthcare provider can also give you tips on how to maintain a lifestyle that can help prevent obesity.

A Quick Review

Your genetics often play an important role in the development of obesity. However, in most cases, obesity occurs due to a combination of genetic and environmental factors.

If you have a family history of obesity or have a genetic mutation that can increase your risk of obesity, then you may also be more likely to gain weight if you live a sedentary lifestyle or eat an unbalanced diet.

However, obesity is largely preventable and manageable. Talking to your healthcare provider can help you understand how you can minimize your risk and develop a weight management plan that's right for you.