When the American Medical Association classified obesity as a disease, Nikhil Dhurandhar, a researcher and vice president of The Obesity Society, said he welcomed the news as an acknowledgment of the challenges people face fighting the battle of the bulge. But he wondered if the declaration went far enough.
Like a growing number of experts, Dhurandhar believes the accumulation of excess fat is likely to have multiple causes beyond a potato-chip-and-couch-potato lifestyle.
Dhurandhar likens obesity to other chronic diseases. Just as the term cancer covers the numerous conditions that occur when abnormal cells divide out of control, obesity may not be a single disease but rather, a group of diseases tied together by the symptom of too much body fat, he said.
"It may look the same on the outside, but what triggers the condition varies from person to person and may require a different treatment to control," he said. "Down the road, we need to figure out why people become fat and then tailor their treatment to address the underlying causes."
Dhurandhar's own studies at Pennington Biomedical Research in Baton Rouge, La., focus on obesity-causing viruses. He discovered the viruses in chickens back in the 1980s and has since associated the presence of certain viral antibodies in the bloodstream of humans to increased body weight.
In one of his landmark studies of 500 people, 30 percent of the obese patients tested positive for the virus, compared to only 11 percent of the lean individuals.
Dhurandhar is quick to point out that he doesn't believe most obesity is infectious in nature, but said that the discovery of a "fat bug" should be a wakeup call to researchers, physicians and anyone struggling with their weight that there may be more to shedding surplus pounds than simply cutting back on calories and putting in a few extra treadmill sessions.
"What good does a starvation diet do if obesity is caused by a virus?" he asked.
Beyond viruses, scientists have identified at least 84 other potential contributors to obesity, Dhurandhar said. They range from genetic to biological to psychological to environmental. Currently, there are about a dozen of these obesogenic culprits under serious study in labs around the world, he noted.
For example, numerous studies now associate lack of sleep with an expanded waistline. Other studies have found that exposure to certain insecticides and plastics disrupt gut bacteria, which may stimulate appetite, slow digestion and accelerate fat storage. And some studies propose a link between the lifestyle habits of great grandparents and their great grandchildren's weight status.
"Not all the causes will wind up being treatable or preventable -- you can't do anything about what your great grandparents ate -- so we will have to focus our efforts on the ones we can control," Dhurandhar said.
Christopher Ochner, director of research development and administration at the Mt. Sinai School of Medicine in New York said he agreed with Dhurandhar's idea that there could be multiple contributors to obesity, but said it complicates matters to classify obesity as multiple diseases.