They hope this will cause doctors to take it more seriously and that insurance companies will pay for more of the treatments.
Doctors say recognizing obesity as a disease will likely change the way they view and treat patients.
"When we re-conceptualize something as a disease what we are really saying is this is not all your fault, there's something genetic going on, there's something in the environment going on," Dr. Hilary Seligman said.
Dr. Seligman, who works at San Francisco General Hospital, says it's quite likely patients will now be able to get access to treatment not usually covered by their insurance.
"If we could have that type of support for people to take care of their obesity, we may be able to make some headway," she said.
Obesity is linked to diabetes, which may lead to heart disease and strokes.
The AMA has been concerned about the dramatic rise in the obesity rate, up 50 percent between 1997 and 2012.
Today, nearly 30 percent of American adults are considered obese. Childhood obesity has more than doubled in the past 30 years.
On the other hand, some worry the AMA calling obesity a disease may lead people to seek quick fixes and discourage them from making changes in their lifestyle.
"We have to get activity back into everyone's lives especially our children," said Dr. Richard Besser during ABC's Good Morning America. "Get them exercising, moving in school and after school, get them eating healthy foods in appropriate amounts. We have to do that for everyone and that's what the AMA should be talking about. Totally, it's about prevention."
A recent survey done for Kaiser Permanente found people are willing to take action to reduce obesity in their own lives.
This survey also found Americans believe their local K-12 schools should play the biggest community role in fighting obesity. 90 percent endorsed the schools playing the biggest role on this issue.