Obesity has reached startling proportions in the United States and around the world, with 35 percent of American adults and 17 percent of children classified as obese, according to studies conducted by the Centers for Disease Control and Prevention. Resulting economic costs due to lost productivity alone are estimated to total over $66 billion annually. Due to this rise in obesity, for the first time, the current generation of American children are not expected to live as long as their parents. These statistics describe an epidemic.

Such drastic figures have led to increasing calls to classify obesity as a disease. In 2004, Medicare removed language naming obesity as a disease from its coverage manual. In 2008, the Obesity Society declared its support for classifying obesity as a disease. Then, in a seminal 2013 statement, the American Medical Association classified obesity (which it defined as a body mass index over 30) as a disease. In doing so, the AMA went against its Council on Science and Public Health, which had been studying the issue for a year and which rejected the disease classification due to its conclusion that the BMI measure was flawed.

Thus, the path to obesity’s classification as a disease has been and continues to be controversial. Overall, the disease classification is valid because obesity fits within the definition of disease and because disease classification will lead to the better treatment and reduced stigmatization necessary to curb the epidemic. While some detractors argue that such a classification will encourage personal irresponsibility, evidence suggests that just the opposite is likely to occur.

Obesity fits the definitions of disease. While there is no single, widely accepted definition, people with obesity have hormonal imbalances, neurotransmitter deficiencies and nutritional exhaustion, fitting one disease definition of “impairing bodily function.” Obesity is like other chronic diseases in that it can be treated, managed and controlled. While behavioral patterns contribute, the root causes are other biological and genetic factors. The AMA describes obesity as a “multimetabolic and hormonal disease state” that can cause other medical conditions such as heart disease, Type 2 diabetes, hypertension, sleep apnea, arthritis and some cancers. While there are some behavioral causes (high-calorie diet and inactivity), other diseases are also exacerbated by behaviors — lung cancer by smoking and kidney disease by alcohol consumption, for example — and these behaviors do not preclude disease classification. Obesity should be viewed similarly, as a genetically and environmentally caused disease that stems from lifestyle factors.

Perhaps more importantly than the definitional semantics, obesity should be classified as a disease because such a classification will lead to more resources, better treatment and less stigmatization. Preliminary analyses since the 2013 AMA announcement suggest that disease classification will lead to more obesity research funding, more obesity-reducing public health initiatives and greater insurance coverage for obesity treatment. The disease designation also forces physicians to take obesity more seriously and provide more support to their patients with obesity. As recently as 2007, only 28.9 percent of physician visits with patients who were obese included obesity-related education or counseling. By removing stigma and reframing obesity as a disease rather than a “lack of willpower” that could be solved by simply “eating less,” this classification has the power to remove health providers’ biases and improve care of their patients.

One valid argument against classifying obesity as a disease is that such a medicalization of the condition might encourage a culture of personal irresponsibility. People with obesity, detractors argue, might conclude that because their obesity is a disease, it is out of their control and not their fault. Thus, the role of individual decision-making around diet and exercise is de-emphasized, even when these behaviors are critical to fighting their obesity. However, several studies suggest that a disease classification will do just the opposite, removing shame and self-destructive cycles and validating the struggles of those with obesity. Interventions that shift responsibility from the individual to the collective, which acknowledge the obesogenic environment and create changes at the environmental level, have shown to be more effective in combating obesity than interventions that focus on individuals. Individual behavior change is hard and modifying the environment works better.

The American Medical Association was correct in defining obesity as a disease. Beyond fitting the most commonly accepted definitions of disease, obesity should be classified as such because doing so will increase resources, improve treatment and decrease stigmatization — all critical in stemming the epidemic of obesity that threatens millions of lives and costs billions of dollars in the United States and around the world. As of 2016, 26 percent of adults in Connecticut are obese, according to The State of Obesity: Better Policies for a Healthier America. Obesity is the disease of the twenty-first century, and it is critical that medical and public health professionals use this disease classification as a tool to fight the epidemic.

Kelly Hall is a graduate student in the School of Public Health. Contact her at kelly.hall@yale.edu .