A chronic disease is a health condition that lasts for at least a year, according to the U.S. Centers for Disease Control and Prevention (CDC). Chronic diseases may limit someone’s ability to do daily activities. They often require medication or other ongoing medical treatment.

According to the CDC, obesity is one of the most common chronic diseases in the U.S. Childhood obesity affects 1 in every 5 kids in the U.S., while the prevalence of obesity for adults is 2 out of every 5 people. Obesity has been associated with different changes in the body, including impaired fertility and bone and joint problems. People who are diagnosed with obesity are also more likely to be diagnosed with other chronic diseases, like hypertension (high blood pressure), sleep apnea, type 2 diabetes, and some forms of cancer.

If you’ve heard some people say that obesity is or isn’t a disease, you may be confused. Even in the medical community, not everyone agrees on the definition of obesity as a disease. There are also different opinions on how to measure obesity. Here’s why many health professionals do consider obesity a chronic disease and what that means for you.

When Was Obesity Declared a Chronic Disease?

In 2013, the American Medical Association officially recognized obesity as a disease. Since then, most major healthcare organizations have agreed with this stance, particularly in the United States. Outside of the U.S., the World Health Organization (WHO) and the European Parliament also consider obesity to be a chronic disease.

However, obesity isn’t recognized as a disease everywhere. The government of the United Kingdom does not formally call obesity a chronic disease. Nonetheless, the U.K.-based Royal College of Physicians declared obesity a disease in 2019. This lack of consistency can cause problems in how obesity is viewed and treated.

Recognizing obesity as a disease shapes how it’s viewed by healthcare providers, health insurance companies, and society in general. For example, doctors and medical staff may get more training in treating obesity — as they do for other diseases. More money may go to obesity research. And there’s a better chance that insurance carriers will help pay for obesity-related medical care. This shift to thinking about obesity as a chronic health condition rather than a personal problem opens doors to different treatment options.

What Are the Classifications of Obesity?

Part of the issue is that people may define “disease” differently. Disagreements about what the word disease really means have led to conflicting views about obesity. There’s also controversy about how to measure obesity.

Those who say obesity isn’t a disease argue that it doesn’t cause health problems for everyone who has it. Simply being at a higher weight does not always come with any other symptoms. And that’s true. Some studies also show that obesity offers protective health effects for certain conditions.

Traditionally, obesity is diagnosed based on a person’s body mass index (BMI) score. This number is calculated using height and weight. (Technically, it’s weight in kilograms divided by height in meters, squared.)

BMI scores are broken down into different categories:

• Underweight — BMI less than 18.5
• Healthy or normal weight — BMI between 18.5 and 24.9
• Overweight — BMI between 25 and 29.9
• Obesity — BMI of 30 or higher

There are also three classes of obesity:

• Class 1 obesity is a BMI score between 30 and 34.9.
• Class 2 is a score between 35 and 39.9.
• Class 3 is a BMI of 40 or higher.

Class 3 is also called “severe obesity.” Each category is associated with different health risks, including reductions in life expectancy.

BMI is a quick and simple tool that helps healthcare providers screen for obesity, but it doesn’t tell the whole story. BMI doesn’t account for factors like:

• Whether a person has any other health issues
• How much muscle mass they have
• The nutrition of their usual diet
• How much they exercise
• The way their biological sex, ethnicity, or genetics may influence the shape of their body

A BMI score also doesn’t capture where a person carries weight on their body. Extra weight in the waist is linked to issues like heart disease. But a person may have a higher body weight from more muscle mass or extra fat in their lower body. This means that just because two people have the same BMI doesn’t mean they have the same metabolic risk factors.

For example, some people with a low BMI score store fat in places like the liver or pancreas. These people have a higher risk of problems like liver disease or type 2 diabetes despite having a “normal” BMI.

Beyond the BMI

Healthcare providers should review other metrics before diagnosing someone with obesity. Measuring the waist-to-hip ratio is one factor. This ratio gives a better picture of someone’s percentage of body fat. Or, they may just measure the person’s waist circumference (how large it is around). Besides body measurements, it’s also important to consider factors like:

• Family health history
• Bloodwork results
• Any other health conditions
• Whether a person’s body image is affecting their mental health

Each person’s situation is unique and affected by many different factors. There’s no one-size-fits-all way to fully define obesity or the scope of its impact on a person’s life. As the medical field continues to learn more about obesity, there’s hope that better tools will be developed to understand when it’s a health concern that requires treatment.

Living With Chronic Obesity

Calling obesity a chronic disease is a way of acknowledging that it’s something people usually have for a long time. Losing weight may lower your BMI and take you out of the “obese” category, but it doesn’t make it easier to maintain weight loss over time.

Defining obesity isn’t as straightforward as some chronic diseases. Similarly, managing this complex disease isn’t always simple.

People may have higher body weights for different reasons. Some people consume more calories than they burn off. This could be related to the types of foods they eat, how much or how often they eat, and how much physical activity they get.

Environmental factors, such as where someone lives and works, can influence their risk for obesity. Biological factors, like genetics, other medical conditions, hormones, side effects of medication, and stress can also play a role.

Treating Obesity

In the past, obesity treatment focused mainly on following a healthy diet and exercising. And although these two habits are still the foundation for anyone who wants to be in good health, regardless of body size, obesity treatment has expanded to include bariatric surgery and obesity medicine. Some of today’s obesity treatment options stop the body from absorbing fat or target appetite signals in the brain and body. Your healthcare provider can offer interventions based on your specific causes of obesity and health concerns.

Talk With Others Who Understand

MyObesityTeam is the social network for people with obesity and their loved ones. On MyObesityTeam, more than 56,000 members come together to ask questions, give advice, and share their stories with others who understand life with obesity.

Does obesity impact your sense of personal wellness and quality of life? Do you consider it a chronic disease? Share your experience in the comments below, post to your Activities page, or connect with like-minded members in Groups.