'Obesity' should be defined by a person's health, not just their weight, Canada doctors say

"Obesity," long defined using a ratio of height to weight, should be defined by someone's health, new Canadian guidelines say. 

The guidelines emphasize that weight and body fat aren't necessarily indicative of poor health, and that the old model perpetuates weight stigma. 

The new guidelines offer five steps clinicians should take when addressing patients with obesity, starting with asking if they want to talk about their weight. 

While some experts say the update is a step in the right direction, others say it doesn't go far enough. 

An updated clinical guidelines published in CMAJ Tuesday advise doctors in taking a new approach: One that defines obesity not as a ratio of height to weight, as has long been the case, but as a chronic disease in which excess body fat impairs health. 

The authors say the change reflects that people can have excess body fat but still be healthy, that eat-less-move-more approaches to weight loss often backfire, and that weight stigma in healthcare is a health risk in itself.

The new guidelines, which were developed including input from people with obesity including Schaffer, define obesity as "a prevalent, complex, progressive, and relapsing chronic disease, characterized by abnormal or excessive body fat (adiposity) that impairs health." 

The strays from the long-held and highly criticized definition of obesity as a BMI, a height-to-weight ratio, of over 30. That means a 6-foot, 225-pound person is considered obese, whether that person is a muscle-strapped athlete or a junk food fiend who's developed non-alcoholic fatty liver disease. 

The new model recommends doctors address obesity in the clinic using five steps. The first is simply asking patients if their weight is something they'd like to discuss.

That's the most important step because it makes the patient a partner, not a victim of weight stigma, co-author Dr. Sean Wharton of Hamilton's McMaster University said on the podcast. "If we can't get past bias and stigma, the other steps don't really work." 

Next, healthcare providers "assess their story," or take a history to understand potential underlying causes, the patient's goals, and in some cases do tests to identify potential health complications like high blood pressure or pre-diabetes. 

During the third step, "advise on management," clinicians focus on tailoring the patient's diet to the medical conditions they're looking to treat (with a focus on nutrition not calorie-counting) and encourage at least 30 minutes of movement a day. 

While nutrition and exercise don't tend to cause significant weight loss, even modest weight loss or none at all can improve the patient's health. If it doesn't, other therapies can be considered, like psychological support, medications, and surgery. 

The fourth and fifth steps, to "agree on goals" and "assist with drivers and barriers" are meant to support the patient in long-term management of their chronic disease.