Female doctor talking to female patient

Morbid obesity: Risk factors and complications

By Jenilee Matz, MPH Mar 10, 2022 • 8 min


Obesity is a condition that’s marked by having an excessive amount of body fat.

It’s linked with serious health issues, such as heart diseasehigh blood pressure and type 2 diabetes. Morbid or severe obesity is the most serious form of the condition, and it comes with the greatest health risks.

What is obesity?

Obesity occurs when your weight is a certain amount higher than what is considered healthy for your height. The condition is caused by taking in more calories through diet than what you burn through physical activity. Obesity symptoms include having excess body fat. This occurs because your body stores extra calories as fat.

To understand obesity, it helps to understand body mass index (BMI). This is a screening tool used to measure body fat in adults. BMI is your weight in kilograms divided by the square of your height in meters. As your BMI increases, so do your health risks. Ranges for BMI include:

  • Underweight: BMI of less than 18.5
  • Healthy weight: BMI of 18.5–24.9
  • Overweight: BMI of 25–29.9
  • Obese: BMI of 30 and higher

What is considered obese?

A BMI of 30 or above is considered obese. Obesity is further divided into subcategories. The different levels of obesity include:

  • Class 1 obesity: BMI of 30–34.9
  • Class 2 obesity: BMI of 35–39.9
  • Class 3 obesity: BMI of 40 and higher

What is morbid obesity?

You may be considered morbidly obese if your BMI is 40 or greater. Some healthcare providers use the term super morbidly obese to describe someone with a BMI of 50 or higher.

What is the difference between overweight vs. obese?

People who are overweight have a lower BMI than those who are obese. A BMI of 25–29.9 indicates overweight, and a BMI of 30 or greater indicates obesity.

Who is at risk for obesity?

Obesity usually occurs due to a combination of genetic, behavioral and environmental factors, including:

  • Genetics and family influences. Obesity can run in families. Genes may influence the amount of fat you have and where you carry it on your body. What’s more, family members also tend to share unhealthy lifestyle habits that can contribute to obesity.
  • Lifestyle habits. Having an unhealthy diet low in fruits and vegetables and high in calories, saturated and trans fats, and added sugars is associated with obesity. A lack of physical activity and a sedentary lifestyle that includes a lot of time spent in front of screens can lead to obesity.
  • Environmental factors. Obesity is also linked with a low socioeconomic status, living in an unsafe location, limited access to safe recreational facilities, and easy access to unhealthy foods.
  • Age. Obesity can occur at any age, even in children. But the risk of obesity increases with age. This may be due to a loss of muscle mass that often comes with age. Reduced muscle mass often leads to a slower metabolism, which can make it hard to keep weight off.
  • Certain health conditions, such as Prader-Willi syndrome and Cushing syndrome, may cause obesity. Conditions that cause a reduced activity level, including arthritis, may also increase the risk of obesity.
  • Some medications can cause weight gain as a side effect. Examples include antidepressants, anti-seizure medications, diabetes medicines, antipsychotic drugs, steroids and beta blockers.
  • Other factors, such as poor sleep habits and high levels of stress, may also contribute to obesity.

What are health risks associated with morbid obesity?

Carrying excess weight is linked with serious medical problems, such as:

  • Heart disease
  • Stroke
  • High blood pressure
  • High cholesterol
  • Type 2 diabetes
  • Sleep apnea and breathing issues
  • Gallbladder disease
  • Osteoarthritis
  • Certain types of cancer, such as endometrial, liver and kidney cancers
  • Depression, anxiety and other mental health conditions
  • Sexual problems, such as infertility and irregular periods in women and erectile dysfunction in obese men
  • Low quality of life
  • Body pain, trouble with physical functioning and disability
  • Early death

How is obesity treated?

There is no one-size-fits-all approach to treating obesity. Your treatment depends on the cause and severity of your condition and if you have other health issues. The goal of treatment is to reach and maintain a healthy weight. This can reduce your risk of obesity-related health issues. Note that even a modest weight loss of 5% to 10% of your body weight can cut your risks. Treatment will likely include changing your eating habits, increasing your activity level and modifying other behaviors.

Weight management programs can also help people achieve success. Working with a team of healthcare providers, including a registered dietitian, behavioral counselor and obesity medicine specialist, may also help.

Sometimes, lifestyle changes alone aren’t enough to meet weight loss goals. In these cases, your healthcare provider may recommend weight loss medicine, devices or recommend surgery. Bariatric surgery for morbid obesity is common and is often considered one of the more effective obesity treatments. However, surgery also tends to come with more risks than other treatments.

Discuss your treatment options with your healthcare provider. Together, you can come up with a plan to lower your weight and your health risks.

Published March 2022.

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