Is Obesity a Disease? Why the Experts Disagree, and Why It Matters

In 2013, the American Medical Association (AMA) officially defined obesity as a disease. This sparked some controversy, especially because the AMA said there wasn’t enough research to say for sure the previous year. Even after a decade, experts still disagree on whether this was the right decision. 

On one hand, obesity may increase someone’s risk for a number of chronic diseases. In many ways, defining obesity as a disease is mostly a matter of public health policy. In the best light, this categorization has helped to increase funding, research, access to care, and insurance coverage. 

On the other hand, “disease” suggests that fat is abnormal. Over half of American adults have been diagnosed with obesity. And this label creates a harmful perception that weight alone is an accurate measure of health.

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We’ll explain the controversy behind the definition of obesity and how this can directly affect your own health and medical care.

What is obesity? 

Obesity is a condition defined by someone's body weight and size. But experts disagree on the exact definition. 

The CDC defines obesity using body mass index (BMI). BMI is calculated using a person’s weight and height. It’s used to categorize someone’s weight as: 

• Normal: 18.5 to 24.9 

• Overweight: 25 to 29.9

• Obese: 30 or greater 

This definition is controversial because BMI is an imperfect measure of body composition. And it does not account for the natural variation in body fat based on factors like age, sex, and race.  

The World Health Organization (WHO) defines obesity as “excessive fat accumulation that may impair health.” But this is also controversial because it’s not always clear when someone’s percentage of body fat becomes a health risk.

Since experts can’t agree on how to define obesity, it’s no surprise they also disagree on whether obesity should be considered a disease. 

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Is obesity a disease?

It’s unclear whether obesity fits the traditional definition of a disease. But multiple health organizations in the U.S. and around the world say it does. The WHO first recognized obesity as a disease in 1948. But most organizations did not follow until much later. 

In the U.S., the National Institutes of Health (NIH) didn’t follow the WHO’s footsteps until 1998. But this did not get much attention until the American Medical Association (AMA) also voted to label obesity as a disease in 2013. 

After that, other organizations followed. This includes the:

• American Association of Clinical Endocrinologists 

• American College of Cardiology

• American College of Surgeons

• American Heart Association

This movement was in response to the increasing number of U.S. adults and children affected by obesity. The AMA and other expert organizations wanted to draw public attention to the way obesity can be a risk factor for other diseases. These include:

• Type 2 diabetes

• High blood pressure

• High cholesterol

• Heart disease

• Certain cancers, like breast cancer

• Stroke

• Gallbladder and liver disease

• Arthritis

• Sleep apnea

Health experts hoped to slow down increasing rates of obesity with improved awareness, research, and treatments. But not all health experts agree that this has been helpful. 

Why do experts disagree on whether obesity is a disease?

Experts disagree on whether obesity is truly a disease for many different reasons. Critics of the decision are concerned it creates a harmful perception that weight equals health. They think it ignores two important points. Let’s take a closer look.

Larger bodies can be normal

Some experts point out that “disease” means the body is functioning abnormally. But a larger body size may be “normal.” And fat accumulation can be a normal change in response to the environment. Given these changes are natural and even protective, they argue that obesity is not a disease.

Most experts still acknowledge that excess body fat poses health risks. But they think obesity may be more accurately defined as a risk factor rather than a disease — similar to the way age is defined as a risk factor. No one considers getting older a “disease.” Instead, it’s considered a natural process that increases the risk for certain medical conditions.

BMI is a poor measure of health

In the U.S., BMI is how providers define obesity. But it does not tell the whole story of someone’s health. In the same way that not all older adults have age-related diseases, not all people identified as “obese” have obesity-related disease. 

For example, two people may have the same BMI but very different bodies. BMI does not account for physical features that may be more relevant indicators of health:

• Amount of body fat: Someone’s weight is a poor indicator of their percentage of fat. And studies show that muscle mass may be a better way to predict someone’s risk for serious health conditions. 

• Distribution of body fat: The location of fat on the body also has an important effect on health. For example, waist size (and fat centered around the abdomen) may be a better predictor for conditions like Type 2 diabetes than overall body fat. 

In other words, someone with a high BMI may be perfectly healthy. And someone with a normal BMI may be at high risk for many diseases traditionally associated with obesity. 

The pros and cons of defining obesity as a disease

Labeling obesity as a disease may have significant implications for treatment and health outcomes for people in larger bodies. Let’s take a look at some of the pros and cons.

Pros

Some of the pros of defining obesity as a disease include:

• Increased funding and research: This can help advance understanding of obesity as a condition. That has led to better knowledge about the root causes of obesity, the potential health risks, and treatment interventions.

• Public awareness: There’s been more attention to the potential health risks associated with weight. There has also been a decline in public perception that obesity is simply the result of lifestyle choices. People now have a better understanding of the important role that genetics and environment play in body size.

• Access to care: This has improved for people identified as “obese.” This includes improved screening and prevention for obesity-associated conditions. There are also more treatment options — like nutrition counseling, medications, and bariatric surgery.

• Insurance coverage: Coverage has increased for people seeking treatment for their weight. Medicare covers weight screening and counseling for those with a BMI in the obese category. 

Cons

This shifting emphasis on obesity has come with some disadvantages as well. Here are some downsides:

• Increased weight stigma: This refers to the negative thoughts and actions directed toward people in larger bodies. And weight stigma increases someone’s risk for negative health outcomes — like weight gain, disordered eating, depression, and suicide risk.

• Decreased quality of care: Weight bias discourages people from seeking medical evaluation. It also means people in larger bodies are less likely to get the proper screening, testing, and treatment they need and deserve for symptoms and conditions unrelated to their weight.

• Medicalization of obesity: This means categorizing obesity as a medical problem rather than a social problem. This minimizes the relationship between body size and social determinants of health. Social determinants of health include things like access to nutritious food, financial resources, safe places to exercise, and community safety. 

• Overtreatment: People who are healthy in larger bodies may be overtreated with medications and surgeries that they don’t need.  

• Increased cost: This includes costs associated with unnecessary testing and treatment. It can also increase insurance premiums for people who are classified as obese. 

Tips for talking to your provider about weight

If you have experienced weight bias — or you’re worried about it on your next healthcare visit — there are ways you can advocate for yourself. 

Here are some tips that can help make your next healthcare visit a positive, supportive experience for you:

• Find the right provider for you. You deserve a provider who listens to you and develops an individual approach to your health. Don’t be afraid to switch providers if you do not feel safe and supported by their care.

• You do not need to be weighed. If being weighed feels stressful or traumatic, you can tell the staff you prefer not to be weighed. If a weight is absolutely necessary, you can ask to provide a weight you took at home. Or ask to turn around on the scale and not be told the number.

• You can lead the discussion. Tell your provider that you prefer your weight not be addressed as a medical problem during your appointment. Or if you do have any concerns about your weight, don’t be afraid to be honest and lead the conversation. This is especially important if you feel like your weight is affecting your mental health. 

• Provide feedback. If you experience weight bias or stigma at any point in your healthcare visit, don’t be afraid to speak up to your provider. More and more providers are making an effort to address this problem in their clinics. This will help you get the care you deserve, and it may help others in a similar position. 

Self-advocacy can be a great way to get the care you deserve. And you don’t have to go it alone. There are lots of advocacy organizations and community resources that can help. A good starting point is our GoodRx guide on living healthy in a larger body. 

Why trust our experts?

Written by:

Katie E. Golden, MD

Katie E. Golden, MD, is a board-certified emergency medicine physician and a medical editor at GoodRx.

Reviewed by:

Sophie Vergnaud, MD

Sophie Vergnaud, MD, is the Senior Medical Director for GoodRx Health. An experienced and dedicated pulmonologist and hospitalist, she spent a decade practicing and teaching clinical medicine at academic hospitals throughout London before transitioning to a career in health education and health technology.

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