“Morbid obesity” is a term many have heard, but it’s considered outdated by the medical community. Organizations like the World Health Organization and National Institutes of Health now use “class 3 obesity” or “severe obesity” instead. This shift reflects a more precise and less stigmatizing way to describe higher body weights. According to the Centers for Disease Control and Prevention (CDC) and the National Center for Health Statistics, the prevalence of severe obesity — meaning how common it is in the population — was around 9 percent in the U.S. between August 2021 and August 2023.

Severe obesity is associated with a higher risk of health issues like heart disease, mental health challenges, and joint pain. In this article, you’ll learn about the key differences between obesity and severe obesity, the health risks involved, and the options available to improve your quality of life.

1. Body Mass Index Scores

The main difference between obesity and severe obesity lies in the amount of body fat a person carries and how it impacts their health. This is usually measured by the body mass index (BMI), a tool based on weight and height. The CDC defines three classes of obesity in adults 20 or older:

• Class 1 obesity — A BMI score between 30 and 34.9
• Class 2 obesity — A BMI score between 35 and 39.9
• Class 3 obesity — A BMI score of 40 or higher

In addition to BMI, doctors will also sometimes look at waist circumference. A waist circumference over 35 inches for women or 40 inches for men is associated with some health conditions, such as heart disease, type 2 diabetes, and high blood pressure. A larger waist means more visceral fat, or body fat around the organs. The risk for these health conditions increases directly with the amount of visceral fat.

Severe obesity increases the risk of serious health conditions like heart disease, type 2 diabetes, and metabolic syndrome, which can shorten life expectancy and harm quality of life.

BMI and waist circumference are commonly used measurements, but they don’t capture individual factors that are also important to understanding a picture of overall health. These include:

• Age
• Activity level
• Any other health conditions
• Body composition (the amount of muscle and fat a person has)
• Physical differences based on ethnicity or gender
• Mental health

It’s important to speak with a healthcare provider to understand your overall health. They can help identify whether treatment options, such as healthy eating, regular physical activity, treating any unaddressed health conditions, or working on improving your mental health, would be best for you.

2. Health Risks

Obesity is a long-term condition where the body carries excess fat. But not all obesity is the same. Class 3 obesity represents the most severe form of this condition. This condition is linked to serious health problems, as it can shorten your life expectancy and negatively impact your daily quality of life.

Heart Disease

Excess weight increases the risk of heart disease, also known as cardiovascular disease. Higher BMI scores and body fat levels are associated with high blood pressure, elevated cholesterol, and other factors that damage the heart.

Losing just 5 percent to 10 percent of your body weight can lower health risks and improve overall well-being, according to Cleveland Clinic.

Research published by the American Heart Association shows that death rates from obesity-related heart disease in the U.S. nearly tripled between 1999 and 2020, with men experiencing the greatest increase. Severe obesity also raises the risk of conditions like type 2 diabetes and metabolic syndrome, which worsen heart health.

Diabetes and Other Metabolic Diseases

Higher body fat levels are associated with a risk of type 2 diabetes and other metabolic diseases. With severe obesity, the risk is even higher. Enlarged fat cells, especially visceral fat cells in the abdominal area, release hormones and chemicals that trigger inflammation, raise blood sugar and triglycerides, and can harm overall health. These changes increase the risk of liver disease, kidney disease, gallstones, heart failure, and stroke.

Other Health Risks

While excess weight poses risks such as high blood pressure, high cholesterol, and metabolic syndrome, severe obesity amplifies these risks and can lead to comorbidities like osteoarthritis, liver disease, and sleep disorders. People diagnosed with class 3 obesity are also more likely to experience reduced mobility and skin conditions, as well as invisible symptoms like joint pain, sleep apnea, and depression.

3. Treatment Options

Your BMI score can help your doctor recommend the best treatment options. For people diagnosed with class 1 or 2 obesity, plans often include lifestyle changes to diet or physical activity, behavioral therapy, and coaching. If you’ve been diagnosed with class 3 obesity, your doctor may also discuss medications or bariatric surgery — these are also recommended for some people with class 1 or 2 obesity if complications of obesity or metabolic syndrome are already present. Every plan should be tailored to your needs, taking into account your mental health and any other health conditions you might have.

Lifestyle Changes for Weight Loss

For most people of any size, making some changes toward healthy eating and physical activity could help them feel better and improve their health. According to the Cleveland Clinic, even a modest weight loss of 5 percent to 10 percent can significantly lower the risk of premature death and improve overall health.

Physical Activity

The CDC recommends 150 minutes of moderate physical activity per week (30 minutes per day, such as five days a week of brisk walking, for example). Multiple studies have shown that activities like walking or cycling improve heart and liver health, even without weight loss.

The Centers for Disease Control and Prevention recommends 150 minutes of moderate physical activity per week, such as brisk walking, which has been shown to improve heart and liver health even without weight loss.

If you have joint pain or mobility issues, physical activity may be more difficult or painful for you. MyObesityTeam members recommend starting small with exercise. “Water-type exercises are good for those that otherwise have pain issues with exercising. I live in a 55-plus apartment complex, and many older seniors here find it too painful to use the gym equipment or participate in the aerobics classes. But they really love water aerobics,” said one member.

Healthy Eating

Improving your diet plays a key role in managing weight and overall health. Your doctor is likely to recommend trying to follow a balanced diet to help improve your health.

Here are a few tips you might try to improve your diet:

• Focus on eating foods with protein and fiber, while reducing sugar, fat, and refined carbs.
• Drink plenty of water to stay hydrated.
• Avoid high-calorie, low-nutrient foods like packaged snacks, cakes, cookies, soda, and alcoholic beverages.
• Experiment with healthier versions of your go-to snacks.

Medication for Obesity

Several classes of medication have been approved to help treat severe obesity. These treatments may reduce appetite or affect how your body absorbs fat and nutrients. Medications are more commonly recommended for class 3 obesity than for class 1 or 2. Some of these medications, such as glucagon-like peptide 1 (GLP-1) receptor agonists, were initially created to treat diabetes, and later their purpose was extended to weight loss as well. They work best when combined with a balanced diet and regular physical activity.

Surgery for Severe Obesity

You may have heard of bariatric surgery. In general, weight loss surgery involves making changes to your stomach or intestines that help you lose weight. Because surgery can be dangerous to your health, it is only typically recommended for people with severe obesity, people for whom lifestyle changes and medication have not worked, or people who have severe health issues related to weight.

Types of weight loss surgery your doctor might recommend for class 3 obesity include:

• Biliopancreatic diversion with duodenal switch (BPD/DS)
• Gastric bypass (Roux-en-Y)
• Sleeve gastrectomy

Coping With a Severe Obesity Diagnosis

No one likes the phrase “morbid obesity,” and many people have struggled with this term being part of their diagnosis. According to the Obesity Medicine Association, one key reason the term “morbidly obese” has been largely dropped by the medical community is because the word morbid has an unpleasant meaning outside of medical settings. This can lead to stigma from others and negative feelings for the people who are labeled with the term. As one MyObesityTeam member put it, “Doctor could’ve left out the word ‘morbidly’ … ugh.”

For others, changing the diagnosis itself becomes the goal. “My doctor asked me what I wanted to weigh when I was done,” said a MyObesityTeam member. “I replied, ‘I don't care! What I really want is for you not to put in my charts “morbidly obese.” I want to be healthy!’”

Obesity and Mental Well-Being

Obesity is linked to discrimination and social stigma. If you’re feeling anxiety or hopelessness related to your body size, it's important to remember that you are not alone. There are always options to build resilience. Discuss your feelings and goals with your doctor. They may recommend a combination of strategies and therapies to improve your mood, mental health, and overall quality of life.

Talk With Others Who Understand

MyObesityTeam is the social network for people with obesity and their loved ones. On MyObesityTeam, more than 55,000 members come together to ask questions, give advice, and share their stories with others who understand life with obesity.

Are you living with obesity? Have you struggled with a severe obesity diagnosis? What helps you stay motivated on your journey? Share your experience in the comments below, or start a conversation by posting on your Activities page.