What does this mean for patients?
There are also two recently-approved obesity drugs, Qsymia and Belviq, that can be prescribed to obese patients.
"It's something that we have to do," he said of the new classification.
In April, Johns Hopkins Medicine researchers conducted a small study of primary care doctors, and found they were less likely to build an emotional rapport with overweight and obese patients than they were with normal weight ones.
The researchers pointed out that empathy is essential for patient care, making them more likely to adhere to medical recommendations.
Obesity's new disease-peg may also make more Americans realize what unhealthy eating and inactivity could be doing to their health.
"Recognizing obesity as a disease will help change the way the medical community tackles this complex issue that affects approximately one in three Americans," Dr. Patrice Harris of the AMA said in a statement.
"The AMA is committed to improving health outcomes and is working to reduce the incidence of cardiovascular disease and Type 2 diabetes, which are often linked to obesity."
In Studio, In-Depth:
Hear John & Susan with BariatricSurgeon Aaron Hoffman MD
Medical Director at Kaleida's Center for Minimally invasive surgery at Buffalo General Medical Center.
An in-depth conversation in three parts, from Buffalo's Early News Thursday
Obesity is defined as a body mass index (BMI) -- a ratio of height over weight -- of 30 or higher. People are considered normal weight if they have a BMI between 18.5 and 24.9
While obesity may not have formally been considered a disease by doctors until now, the health condition has certainly been linked to diseases by growing bodies of research.
Studies have linked obesity to risk increases for heart disease, Type 2 diabetes, stroke, liver disease, sleep apnea, breathing problems, osteoarthritis and joint pain, infertility, sexual side effects and cancers of the breast, colon, esophagus, pancreas and kidneys
Exclusive WBEN Audio
On The WBEN Liveline
"Greg", a bariatric surgery patient
shares story of having his stomach "stapled"
The 2013 "Annual Report to the Nation on the Status of Cancer" found significant rises in obesity-related cancers over the past three decades.
Heart disease in particular is the leading cause of death in the United States for men and women. The American Heart Association says that too much fat around the waist can contribute to heart problems by lowering HDL "good" cholesterol and raising "bad" LDL cholesterol, blood pressure, and triglyceride levels.
AMA re-classifies Obesity as a Disease
from the US Centers for Disease Control
...Affects some groups more
The yearlong study indicates that the most common weight-loss surgery, gastric bypass, can effectively treat diabetes in patients with mild to moderate obesity — about 50 to 70 pounds overweight, the researchers reported Tuesday in the Journal of the American Medical Association.
Other studies have shown the operation can reverse diabetes in severely obese patients, although sometimes the disease comes back.
About a third of the 60 adults who got bypass surgery in the new study developed serious problems within a year of the operation, though some cases were not clearly linked with the surgery. That rate is similar to what's been seen in previous studies.
But for the most serious complications — infections, intestinal blockages and bleeding — the rate was 6 percent, slightly higher than in earlier research.
The most dangerous complication occurred in one patient when stomach contents leaked from the surgery site, leading to an overwhelming infection, leg amputation and brain injury. Lead author Dr. Sayeed Ikramuddin, an obesity surgeon at the University of Minnesota, called that case "a fluke."
A journal editorial says such devastating complications are rare, but that "the frequency and severity of complications ... is problematic" in the study and that the best way to treat patients with both obesity and diabetes "remains unknown."
A research review in the journal said more long-term evidence on risks and benefits is needed to determine if obesity surgery is an appropriate way to treat diabetes in patients who aren't severely obese — at least 100 pounds overweight.
More than 20 million Americans have Type 2 diabetes; most are overweight or obese. Diabetics face increased risks for heart disease and strokes, and poorly controlled diabetes can damage the kidneys, eyes and blood vessels.
About 160,000 people nationwide undergo various types of obesity surgery each year. Bypass surgery, the type studied, involves stapling the stomach to create a small pouch and attaching it to a lower part of the intestines.
The American Society for Metabolic & Bariatric Surgery says obesity surgery is safe and that the death rate is less than 1 percent, lower than for gallbladder and hip replacement surgery.
The study involved 120 patients at five hospitals in New York, Minnesota and Taiwan. All patients got medicines for diabetes, obesity, cholesterol and/or high blood pressure. They all were advised to cut calories and increase physical activity.
Sixty patients also had surgery, and the two groups were compared after one year.
The surgery group lost on average nearly 60 pounds and 75 percent lowered blood sugar levels to normal or near normal levels. The non-surgery group lost an average 17 pounds and just 30 percent reached the blood-sugar goal. The surgery group also needed less medication after the operation.
The researchers say the diabetes changes were likely due to the weight loss but that hormonal changes affecting blood sugar may have contributed.
The surgery group showed a trend toward having less high blood pressure and elevated cholesterol — both major risk factors for heart disease, although those between-group differences could have been due to chance.
Ikramuddin, the lead author, said the study results don't mean that all mildly obese diabetics should have obesity surgery, but that "in the correct patient, surgery might be an important thing to consider."