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December 30, 2023

Why Obesity is a Disease

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The American Medical Association (AMA) designated obesity a disease in 2013. As a result, the idea that obesity is caused by insufficient willpower, lack of discipline, and bad choices began to transform.

The headline, “AMA Recognizes Obesity as a Disease” was catapulted across both academic and mainstream media. Obesity was no longer a conversation topic tucked away in a dusty corner but was instead sprinkled across national news for the public to scrutinize. From TED Talks to the New York Times, obesity specialists were asked to weigh in on this groundbreaking and somewhat controversial topic and to answer the question, “is obesity a disease?”

The debate continues today.

Is Obesity a Disease?

New ideas can take a long time to catch on, especially when they have to overcome deep-seated beliefs. Along with those headlines proclaiming the AMA’s 2013 announcement came articles making a counter argument. A Forbes headline promised to explain “Why Labeling Obesity as a Disease is a Big Mistake.” The author argues that smoking became much less common because people changed their behavior in response to health information. Conversely, they argue, labeling obesity a disease removes incentive for behavior change such as eating less or exercising more.

For some, labeling obesity as a disease invalidates the importance of discipline, proper nutrition, and exercise and enables individuals with obesity to escape responsibility. For others, seeing obesity this way is a bridge to additional research, coordination of effective treatment, and increased resources for weight loss.

Another article from that time, this one in The Atlantic, began, “The relationship between health and body weight is not as straightforward as the American Medical Association might have us believe.” This one posits that accepting the “disease” label doesn’t mean that lifestyle change is unnecessary. (And, one could argue, the AMA never said that it was unnecessary.)

Why OMA Says "Yes"

OMA's position is that obesity should be considered a disease.

Our Obesity Algorithm® provides a comprehensive definition. Obesity is a “chronic, relapsing, multi-factorial, neurobehavioral disease, wherein an increase in body fat promotes adipose tissue dysfunction and abnormal fat mass physical forces, resulting in adverse metabolic, biomechanical, and psychosocial health consequences.”

Individuals with obesity have an increased accumulation of fat not always attributable to eating too many calories or lacking physical activity. They experience impaired metabolic pathways along with disordered signaling for hunger, satiety (the feeling of fullness), and fullness (the state of fullness).

For many, efforts to lose weight are met with unyielding resistance or disappointing weight regain. According to the University of Michigan’s school of medicine, 90% of people who lose weight will regain most of it.

The pathology of obesity is vast and varies based on the cause of weight gain. There is not just one type or cause for obesity. Obesity sub-types include congenital, stress-induced, menopause-related, and MC4R-deficient, to name a few. Obesity is related to genetic, psychological, physical, metabolic, neurological, and hormonal impairments. It is intimately linked to heart disease, sleep apnea, and certain cancers. Obesity is one of the few diseases that can negatively influence social and interpersonal relationships.

Why Some Take Issue with Calling Obesity a Disease

In the U.S. there is a culture of personal responsibility and personal choice when it comes to health. A paper published in 2020 in Perspectives in Psychological Science delved into this phenomenon. It opens, “The United States suffers high rates of preventable lifestyle disease despite widespread calls for people to take responsibility for their health.” The authors link these attitudes to everything from the self-help publishing industry to parks and recreation departments.

The idea that obesity is a disease appears, on the surface, to contradict this reliance on personal responsibility. It should be noted that the debate is not limited to the U.S., as articles like this one in the British Medical Journal illustrate. Consider, however, that a patient with any disease can receive recommendations for diet or lifestyle changes. Nutrition and exercise are no less important, whether we call obesity a disease or not. A doctor may wish to avoid calling obesity a disease if they believe it could give a patient the sense that their choices do not matter to their health.

Cleveland Clinic points out that one hurdle to understanding obesity as a disease is that it is “silent,” meaning it doesn’t have specific symptoms. Instead, it is measured by a person’s weight-to-height ratio, or BMI, which is an imperfect measurement at best. Other measures suggested by some in the profession include waist circumference or hip-to-waist ratio.

Another issue is simply the lack of consensus on how to define disease. Some definitions, in fact, require symptoms, bringing us back to the point above.

Obesity, as we know, is related to a wide range of health conditions and diseases, including diabetes, heart disease, sleep apnea, and cancer.

Wider Implications of Treating Obesity as a Disease

Treating obesity as a disease brings several benefits, which the AMA listed at the time of its designation:

The rise of new obesity medicines, including strong public interest in GLP-1 receptor agonists, helps to frame it more as a disease. The general public tends to think of a disease as having a corresponding medication to treat it. As more patients come in asking about these medications, it can help to explain to them that this disease warrants a multi-pillared approach, which can mean addressing lifestyle factors too.

Frequently Asked Questions

Is obesity a disease or a disorder?

Obesity is a chronic disease. According to the Centers for Disease Control and Prevention (CDC), obesity affects 42.8% of middle-age adults. Obesity is closely related to several other chronic diseases, including heart disease, hypertension, type 2 diabetes, sleep apnea, certain cancers, joint diseases, and more.

Is obesity considered a chronic disease?

Yes. Obesity, with its overwhelming prevalence of 1 in 6 adults in the U.S., is now recognized as a chronic disease by several organizations, including the American Medical Association.

The CDC defines “chronic disease” as conditions that last one year or more and require ongoing medical attention or limit activities of daily living, or both. Three leading chronic diseases are heart disease, cancer, and type 2 diabetes.

Obesity is associated with all three of these chronic diseases. The CDC also acknowledges widespread consequences of obesity when compared to normal or healthy weight for many serious health conditions, including all causes of death, hypertension, diabetes mellitus, coronary heart disease, stroke, and many cancers.

Of the $3.3 trillion spent annually on medical care for chronic conditions, obesity alone is associated with $1.4 trillion.

What is the link between obesity and mental health?

Numerous studies support a strong link between obesity and mental health. This relationship appears to be bi-directional; while mental health disorders increase the risk for obesity, having obesity also increases the risk of mental health disorders, especially in certain populations.

Mental health disorders can increase the risk for obesity for several reasons:

  • Medications used to treat psychiatric illnesses can cause weight gain and insulin resistance, contributing to obesity.
  • Mental illnesses affect behaviors such as decreased sleep, poor eating behaviors, and reduced physical activity, which can contribute to the development of obesity.

Conversely, having obesity increases the risk for depression. This is likely due to numerous complex factors, including poor self-image and depressed mood in response to weight bias and stigma, decreased activity due to joint and back pain associated with excess weight, and biological disruptions caused by chemicals secreted by fat cells when a person has obesity.

The link between obesity and mental health is complex and multi-faceted. It is important that patients with mental health disorders are monitored for weight, and that people with obesity are screened for mental health disorders.

Is Class III obesity a disability?

People with Class III obesity, formerly called morbid obesity, can have disabling health conditions that result from obesity and could qualify them for disability benefits. However, most people who have Class III obesity are quite able to perform their work functions. Having Class III obesity does not automatically qualify someone for benefits.

Hook, C. J., & Rose Markus, H. (2020). Health in the United States: Are Appeals to Choice and Personal Responsibility Making Americans Sick? Perspectives on Psychological Science, 15(3), 643-664.

Rosen H. Is Obesity A Disease or A Behavior Abnormality? Did the AMA Get It Right? Mo Med. 2014 Mar-Apr;111(2):104-108. PMID: 30323513; PMCID: PMC6179496.