Is Obesity Genetic or Environmental?

Obesity has a variety of underlying causes, most of which are a combination of environmental and genetic variables.

When excess body fat builds up to a dangerous level, it is referred to as obesity, a chronic health problem. Although this can signify different things to different people, body mass index (BMI), which is a measurement of your weight about your height, is usually used to screen for obesity.

BMI isn't a 100% reliable predictor of obesity. It is not a direct indicator of health or fat, and it may not be reliable in people with larger muscle mass, such as bodybuilders. It does, however, give medical professionals and researchers a common tool to track public weight.

A BMI of 30 or over is considered obese. After that, it is separated into classes based on how severe obesity is:
  • Class 1: 30 to <35 BMI
  • Class 2: 35 to <40 BMI
  • Class 3 (severe obesity): 40 or higher BMI
The Centres for Disease Control and Prevention (CDC) released its most recent obesity data in 2020, and it shows that 41.9% of adult U.S. citizens were sampled and had obesity between 2017 and 2020.

Is there a genetic component to obesity?

Genetics can affect the body's metabolic processes, brain networks, and appetite control centres indirectly, as well as directly in cases like Prader-Willi syndrome.

A clinical evaluation published in 2022 states that over 500 human genes have been linked to obesity.

Numerous factors can impact body weight due to these genes. They may cause modifications to blood pressure, inflammatory reactions, insulin metabolism, fat deposition, and the amount of fat circulating in the blood. They could make you want to eat more food, which is energy, but they might also keep you from using it wisely.

Even in cases where there is a remote correlation, certain genes can still have an impact on obesity. For instance, you may be predisposed by specific genes to illnesses like Cushing syndrome, which raises the risk of obesity.

According to research published in 2021, genes account for 40–50% of the variation in body weight, with genes being more important (up to 80%) in those who are obese.

This does not imply that heredity causes weight gain invariably. For the majority of people, this means that, depending on the situation, genetics may increase your risk of gaining weight.

Is there an obesity gene?

While some people's obesity may be caused by mutations in a single gene, obesity is not always caused by a single gene.

Hundreds of genes have been implicated in the development of excess body fat, and the genetic differences causing these variations might differ significantly between individuals who suffer from obesity. One or more genetic variations may be a part of your life.

Based on how genes are involved, there are various types of genetic obesity:
  • Monogenic obesity: weight gain brought on by a single gene mutation. The most often impacted gene associated with obesity is MC4R.
  • Polygenic obesity: An individual's risk of obesity is increased by minor variations in several genes. Polygenic obesity is the most common kind of genetic obesity.
  • Syndromic obesity: Obesity can be directly caused by genetic alterations in certain disorders, such as Prader-Willi syndrome.

What environmental factors most commonly lead to obesity?

Obesity can arise by consistently consuming more calories than you burn, whether or whether genetics plays a role. Environmental influences, which are external variables, are frequently blamed for this energy imbalance.

The built environment surrounding you and the amount of food you eat are examples of environmental influences. They have an impact on how much energy you consume and how your body uses it.

Among the most frequent environmental variables associated with obesity are:
  • sedentary way of living (insufficient exercise)
  • frequent ingestion of foods high in calories
  • exposure to chemicals used in food production that cause endocrine disruption (e.g., pesticides, plastic containers)
  • poor sleep habits
  • chronic stress

Social determinants of health

Obesity is also influenced by a collective set of environmental factors known as social determinants of health (SDOH). The elements that make up your immediate surroundings are your SDOH. Examples of SDOH include income level, neighbourhood crime rate, availability of wholesome food, and exposure to discrimination.

These elements may encourage lifestyle decisions that lead to obesity. For example, you might be less likely to walk outside for exercise if you reside in a neighbourhood with a high crime rate.

How do environmental and genetic variables relate to obesity?

Genetics and environmental factors combine to cause extra fat buildup in the majority of obese individuals.

Environmental influences provide the conditions for lifestyle decisions that lead to obesity, and genetics can make you more likely to gain weight under those conditions.

However, the relationship can be bi-directional, indicating that it benefits both parties. Environmental influences can impact genetics through epigenetic modifications, or variations in gene expression, just as genetics can amp up the impact of environmental factors.

For instance, studies show that environmental variables that contribute to obesity, such as a high consumption of fried foods, inadequate sleep, and a sedentary lifestyle, might alter genes that control obesity.

Your gut flora can change as a result of exposure to endocrine disruptors, which are substances that interfere with hormone signalling in the body and have also been connected to modifications in genetic expression.

Treatment options for obesity

Although treating obesity can be difficult, it usually begins with a lifestyle change that includes reduced calorie intake, balanced eating, and increased physical activity.

Reducing calories consumed and increasing calories burned is not always enough to manage obesity. Losing weight can be quite tough if environmental issues such as stress, sleep patterns, and SDOH are not easily handled.

Energy balance is just one component of many obesity treatment programmes, which also include:
  • nutritional counseling
  • psychotherapy
  • support groups
  • behavioural strategies
  • medication
  • surgery

Can genetic obesity be treated?

Even in cases where genetics play a substantial influence, obesity is frequently curable. A group of medical specialists, such as paediatricians, endocrinologists, obstetricians, nutritionists, geneticists, genetic counsellors, and psychologists, may be necessary for successful care.

Treatment options for genetic obesity consist of lifestyle changes, medication, and surgery, all under the direction of these specialists. Your unique strategy will be based on how your genetics affect the amount of body fat you accumulate.

Treatment options for genetic obesity can differ, such as:
  • treating the underlying illness may help reduce the symptoms of obesity if you have syndromic obesity.
  • If your obesity is caused by exposure to endocrine disruptors, an endocrinologist might advise you to make particular lifestyle adjustments about what you put on and put in your body.
  • In cases where genetic obesity is monogenetic and inherited, modifying one's lifestyle during childhood could lead to better health results as an adult.


Genetics, environment or both may play a role in obesity. However, this does not imply that gaining weight is a constant outcome of having genes linked to obesity.

The majority of obese individuals have underlying genetic characteristics that make them more likely to gain weight in specific situations. Additionally, the relationship operates in reverse: environmental effects have the power to modify your genes, which in turn affects how much fat your body stores.

Any cause of obesity is addressed with a combination of medication, surgery, and lifestyle modifications. Other specialists, such as a geneticist, might join your medical team if genetics plays a major role.

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