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Extreme Obesity: Causes and Complications

Extreme Obesity: Causes and Complications

The normal body mass index (BMI) is 18.5 to less than 25. A BMI of 25 or greater is a cause for concern because being overweight or obese increases the risk of many diseases, including type 2 diabetes, heart attack, and stroke.

Obesity has three categories:

  • Class 1: BMI of 30 to less than 35
  • Class 2: BMI of 35 to less than 40
  • Class 3: BMI of 40 and above

If the doctor tells you that you’re under class 3, then you are considered severely or morbidly obese. What are the causes and complications of extreme obesity?

Causes of Extreme Obesity

extreme obesity

The US Center for Disease Control said that obesity “results from a combination of causes and individual factors.” These causes and factors include:

Diet and Exercise

Reducing the risk of being overweight and obese requires a healthy and balanced diet and regular physical activity.

These help ensure the balance between the calories consumed and used. Excessive intake of calories coupled with a sedentary lifestyle often results in weight gain, which, when left unchecked, can lead to extreme obesity.

Environmental Factors

Note that the person’s behavior on their diet and physical activity may be influenced by their situation at home, school, or workplace.

Case in point: being too busy may make fast food more appealing than cooking meals, and living in an area with no safe side-walk may discourage people from having a walk.

Health Conditions and Medicines

Some health conditions, such as Cushing’s disease and polycystic ovary syndrome (PCOS), may predispose a person to obesity, including extreme obesity.

Likewise, some drugs also trigger weight gain. Examples include some antidepressants and steroids.

Family History and Genetics

Interactions between genes may also play a role in developing obesity. Experts say that while genetic changes happen too slowly to influence the occurrence of obesity, some genes take part in how a person responds to environmental changes by increasing hunger or food intake.

Although rare, it’s also possible that a clear pattern of obesity running in the family is due to the presence of a single variant of a gene (monogenic obesity).

Possible Complications of Extreme Obesity

Morbid obesity can lead to the following symptoms that may interfere with daily routines:

  • Fatigue
  • Difficulty doing physical activity
  • Joint and back pain
  • Increased sweating
  • Breathlessness

Also, a person with extreme obesity may develop low self-confidence or self-esteem, which may result in feelings of isolation.

Besides the day-to-day health issues, let’s not forget that a person with morbid obesity also has an increased risk for various health conditions, including:

  • Type 2 Diabetes – Obesity can make a person resistant to insulin, which may then progress into type 2 diabetes.
  • Hypertension and other heart diseases – Obesity, especially extreme obesity, can make it difficult for the heart to pump. This can lead to hypertension and other cardiovascular diseases.
  • Increased bad cholesterol and triglycerides – These consequences further put the person at risk of heart problems.
  • Sleep apneaExcessive fat in the tongue and neck can block airflow, especially when one sleeps on their back.
  • Gastroesophageal reflux disease – Obesity, especially morbid obesity, overloads and weakens the lower esophageal sphincter, the valve that ensures food will not backflow once it’s in the stomach. The weakening may lead to GERD.
  • Difficulty with physical functioning – This happens due to multiple problems that limit movement. Examples include body pain and osteoarthritis.

Finally, extreme obesity can wreak havoc on the person’s mental health, which may progress into anxiety or even depression.

Key Takeaways

Extreme obesity is characterized by having a body mass index of 40 and above. It is usually a result of a combination of factors, such as genetics, diet, physical activity, and existing health conditions.

Extreme obesity leads to multiple health issues that interfere with the activities of daily living. But it also increases the risk of more serious conditions, such as heart disease, type 2 diabetes, and mental health concerns.

For this reason, it’s crucial to achieve and maintain a healthy weight. If you have problems with your weight loss goals, don’t hesitate to consult your doctor.

Learn more about Obesity here.


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Hello Health Group does not provide medical advice, diagnosis or treatment.


Defining Adult Overweight & Obesity, https://www.cdc.gov/obesity/adult/defining.html, October 15, 2021

Adult Obesity Causes & Consequences, https://www.cdc.gov/obesity/adult/causes.html, October 15, 2021

Obesity, https://www.nhs.uk/conditions/obesity/, October 15, 2021

What is Morbid Obesity?, https://www.urmc.rochester.edu/highland/bariatric-surgery-center/journey/morbid-obesity.aspx, October 15, 2021

Extreme Obesity, And What You Can Do, https://www.heart.org/en/healthy-living/healthy-eating/losing-weight/extreme-obesity-and-what-you-can-do, October 15, 2021

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Written by Lorraine Bunag, R.N. Updated Oct 17
Fact Checked by Bianchi Mendoza, R.N.