What Is Class 3 Obesity? (Formerly Known as Morbid Obesity)
Class 3 obesity is a term that describes what used to be known as “morbid obesity” or “severe obesity.” It’s a chronic disease that can increase a person’s risk of developing other health conditions, such as type 2 diabetes, heart disease, and cancer. Several options are available to help manage and treat class 3 obesity.
To qualify as having class 3 obesity, you must meet one of the following criteria:
You have a body mass index (BMI) of 40 or higher.
You have a BMI of 35 or higher and experience obesity-related health problems, such as high blood pressure.
You are more than 100 pounds above the optimal body weight range for your sex and height.
What Is BMI?
BMI is a tool that doctors use to assess whether you are overweight or have obesity. It uses your height and weight to help estimate your body fat. Specifically, BMI is calculated by dividing your weight in kilograms (kg) by the square of your height in meters (m2).
The obesity classifications based on BMI are:
BMI of 25–29.9: Overweight
BMI of 30–34.9: Class 1 obesity (low risk of other health problems)
BMI of 35–39.9: Class 2 obesity (moderate risk)
BMI of more than 40: Class 3 obesity (high risk)
BMI can correctly estimate body fat for most people, but it’s not accurate for everyone. For instance, someone who is lean with a lot of muscle mass might have a higher BMI, but they don’t have obesity. If this is the case, doctors may use other tools, such as waist circumference, to more precisely evaluate a person’s risk of obesity.
Why Is the Term Class 3 Obesity Used Now?
Today, healthcare providers and organizations, including the World Health Organization (WHO), use the term “class 3 obesity” instead of “morbid obesity" or "severe obesity.”
The term “morbid” was originally used to describe this type of obesity because it often occurs with comorbidities, which means other health conditions that exist alongside a disease. But because the word is associated with unpleasant meanings and stigmas, class 3 obesity is the preferred language when describing this category of obesity.
Symptoms of Class 3 Obesity
Signs of class 3 obesity include a BMI of 40 or higher and body fat distribution concentrated around the waist. Class 3 obesity doesn’t cause any specific symptoms, but there are many associated side effects and complications of the disease, which are discussed below.
Class 3 obesity is a complex disease that likely has several causes. In general, obesity develops when more calories are consumed than the body uses. But every person metabolizes energy differently, and some people are more likely to gain weight than others.
Though anyone can develop class 3 obesity, certain factors that increase your risk include:
Genetics Obesity tends to run in families. Research has shown that specific genes are linked to weight gain.
Hormones Hormone imbalances can affect your metabolism. For example, low levels of thyroid hormone or high levels of the stress hormone cortisol can lead to weight gain.
Cultural Factors Being exposed to a culture that promotes calorie-dense foods and large portion sizes can influence your risk of obesity.
Socioeconomic Status A low socioeconomic status can contribute to weight gain. Lack of access to healthy foods and recreational facilities, like parks, is also associated with obesity.
Environment Exposure to certain chemicals called obesogens can alter your hormones and increase body fat.
Sex Women are more likely than men to develop obesity.
Age Class 3 obesity tends to affect adults ages 40–59 the most.
Race Non-Hispanic Black adults have the highest rates of class 3 obesity.
Doctors might use a variety of tests and methods to diagnose class 3 obesity, including:
A BMI assessment
A waist circumference measurement
A skin thickness measurement
Urine tests
Blood tests that measure your complete blood cell counts, basic metabolic panel, liver function, cholesterol levels, triglyceride levels, kidney function, blood sugars, thyroid function, C-reactive protein (CRP), or vitamin D levels
Other tests, such as an electrocardiogram (EKG) for heart health or sleep study
Treatment options for class 3 obesity typically include lifestyle changes, medications, surgery, and therapy.
Lifestyle Changes
Healthy lifestyle changes is an important part of managing class 3 obesity. Here are some habits that can help you lose weight.
Change your diet. A heart-healthy diet that includes lots of whole, unprocessed foods and gradual calorie reduction can help you manage your weight. A dietitian or nutritionist can help you come up with a safe and appropriate plan. Talk to your doctor before making any drastic changes to your diet.
Exercise. Daily physical activity can help you maintain a healthy body weight. Talk to your doctor about the type of physical exercise and how to start safely before beginning an exercise program.
Get enough sleep. Studies show poor sleep is linked to weight gain. Be sure you are getting enough rest at night. If not, let your doctor know, so you can explore different treatment options.
Manage stress. Too much stress can increase your risk of gaining weight. Yoga, meditation, and breathing exercises can help keep stress at bay.
Medications
Different medicines are available to help people with class 3 obesity lose weight. But doctors usually don’t recommend these drugs alone. Instead, they are given as part of a comprehensive treatment plan that involves lifestyle changes or other approaches.
One medication called orlistat (Alli) stops your gut from absorbing fat in food.
Other medications used for weight loss help decrease your appetite by changing the way your brain controls your urge to eat. These include:
diethylpropion (Tenuate)
liraglutide (Saxenda)
naltrexone/bupropion (Contrave)
phendimetrazine (Bontril)
phentermine-topiramate (Qsymia)
semaglutide (Wegovy)
tirzepatide (Zepbound)
Like all medications, weight loss drugs can cause unwanted side effects. Some common side effects are nausea, diarrhea, and constipation.
Surgery
Weight loss surgery, which is known as bariatric surgery, is sometimes an option for people with class 3 obesity if lifestyle changes and medications don’t work.
There are different types of procedures:
Gastric bypass: Surgeons connect a small part of your stomach to the middle of your intestine. This causes the food you eat to bypass the first part of your intestine, helping to make you feel full with less food and reducing the number of calories your body can absorb.
Sleeve gastrectomy: With this procedure, a surgeon takes out a part of your stomach, which helps you feel fuller when you eat.
Some possible risks and complications of bariatric surgery include:
Infection and bleeding
Blood clots
Heart events
Difficulty absorbing nutrients
Vitamin and mineral deficiencies
Dumping syndrome (food leaks from your stomach into your small intestine more quickly than it should)
Therapy
Behavioral or psychological therapy may be helpful treatments for someone with class 3 obesity. There are different types of therapy options, including individual or group therapy. Some focus on changing your behaviors and habits, while others might address your emotional or psychological responses. A medical professional can help you determine which would be the most effective type for your situation.
Obesity can take a toll on your mental health. Studies show about 43 percent of people with depression have obesity. On the flip side, those who have obesity have a 55 percent increased risk of developing depression during their lifetime.
Research has also suggested other mental health conditions, such as anxiety and eating disorders, are common among people with obesity.
If obesity and mental health conditions occur together, doctors will usually treat both as chronic disorders.
The same lifestyle strategies that promote weight loss and maintenance help prevent obesity. These include:
Eat a variety of vegetables and fruits daily.
Choose whole-grain foods over processed foods made with refined grains and sugars.
Learn and stick to correct portion sizes.
Get 60 to 90 minutes of moderate to intense exercise three to four times per week.
Some research suggests that having class 3 obesity can shorten a person’s life expectancy by up to 14 years. The disease can also negatively affect your quality of life by limiting your physical, social, and financial opportunities.
But it is possible to effectively treat class 3 obesity, which can improve your outlook. People who take prescription medicines for weight management can lose 10 percent of their weight or more. Research has suggested that those who have bariatric surgery can lose 77 percent of their excess weight a year or more after surgery.
Having class 3 obesity can increase your risk for other health problems, including:
Metabolic syndrome, a cluster of conditions that increases your risk of heart disease, stroke, and diabetes. You have metabolic syndrome if you have at least three of these — central obesity, high triglyceride levels, low high-density lipoprotein (HDL) levels, high blood pressure, and elevated blood sugar levels.
Sleep disorders, such as sleep apnea, a condition where you stop breathing during sleep
Depression
Class 3 obesity is a relatively common disease in the United States. According to the Centers for Disease Control and Prevention (CDC), almost 10 percent of adults had class 3 obesity from 2017 to 2020. This means that more than 22 million Americans are living with the disease.
The Takeaway
Class 3 obesity, once known as morbid obesity, refers to a serious form of obesity that significantly raises the risk of various health issues, including heart disease and type 2 diabetes.
Despite its challenges, there's a slate of treatment options aimed at managing weight, from lifestyle changes to medical interventions.
Being proactive by incorporating small, healthy choices daily can substantially improve your well-being.
