New Canadian research questions the notion that one's body mass index, or BMI and weight can automatically determine good health - even when someone is severely obese.

Two studies published Monday suggest re-framing the way medical practitioners look at overweight and obese patients.

In one of the studies, published Monday in the Canadian Medical Association Journal, University of Alberta researchers tested the system using data from a survey of roughly 8,143 people in the two U.S. national health and nutrition surveys.

One in five obese people may not have medical problems, the authors noted.

Researchers found that although 77 percent of overweight or obese people in one survey, and 90 per cent of those in another were classified as Stage 1 or 2, their risk of dying over 20 years of follow-up was substantially lower than people classified as Stage 3 obesity.

CNN reported:

  • Stage one is borderline hypertension and elevated blood pressure. The person may have elevated glucose levels and mild physical symptoms such as pain and aches. The person does not have a clinical disease at this point.
  • Stage two is classified with obesity-related diseases such as hypertension, diabetes and sleep apnea. The person may face limitations on daily activities.
  • Stage three means the person has organ damage such as heart failure, diabetic complications and debilitating arthritis. The person may also be suicidal and depressed.
  • Stage four is the most severe, with end-stage chronic diseases, severe disabilities and functional limitations.

Both studies were published in the Canadian Medical Association Journal and Applied Physiology, Nutrition and Metabolism.

They found that obese people who had no - or only mild - physical, psychological or physiological impairments had a higher body weight in early adulthood, were happier with their higher body weight, and had attempted to lose weight less frequently during their lives.

However, those people were also more likely to be physically active and consume a healthy diet.

Lead author Jennifer Kuk, assistant professor in York University's School of Kinesiology and Health Science, said, "Our findings challenge the idea that all obese individuals need to lose weight."

Kuk and her team looked nearly 6,000 obese Americans over a 16-year time span, comparing their mortality risk with that of slim people.

The researchers - whose findings were published in the journal Applied Physiology, Nutrition and Metabolism - used a newly-developed grading tool, the Edmonton Obesity Staging System (EOSS), which has been found to be more accurate than body mass index (BMI) for identifying who should attempt to lose weight.

Developed by University of Alberta researchers, it is modeled on staging systems that classify the extent and severity of other diseases such as cancer, mental illness and heart disease.

It offers five stages of obesity based on both traditional physical measurements such as BMI and waist-to-hip ratio, plus clinical measurements that reflect medical conditions often caused or aggravated by obesity — such as diabetes, hypertension and heart disease.

Kuk said that in order to determine whether or not they should lose weight, individuals should see a physician to be evaluated using the EOSS criteria.

After adjusting for age, history of smoking and metabolic syndrome — a cluster of conditions such as high blood pressure and diabetes — about two percent of people with scores of zero or one died during follow-up, compared to about 40 per cent of Stage 3 patients.

"That's a huge difference," Dr. Arya Sharma, chair of obesity research and management at the University of Alberta in Edmonton and who first proposed the Edmonton classification system, told Daily Mail.

"What this actually means is if I examine people today and I see that they're Stage 0 or Stage 1, I can tell them to eat as healthy and be as physically active as possible rather than running out and trying to lose weight," Sharma added.