For years, we've been hearing about the dangers of obesity. Obese people are more likely to have heart attacks, stroke, and diabetes, and they should try to lose weight, experts say.

But now a new study finds that it's possible to be obese and healthy.

Doctors use a measure called BMI (short for body mass index) to measure obesity. It's an easy calculation based on height and weight, and if your BMI is over 30, you're considered obese.

A couple of years ago, Canadian researchers developed a more sophisticated measure, called the Edmonton Obesity Staging System (EOSS). It classifies obese people in five categories, or stages, based on risk factors such as blood pressure, chest pain, and fatigue.

To evaluate the EOSS, Jennifer L. Kuk of Toronto's York University, and colleagues examined thousands of patient records from a clinic in Texas. Each patient was assigned to risk groups in the Edmonton system based on an average of 16 years of medical history.

"When we did that we saw that the obese individuals who were categorized in the low risk of the Edmonton Staging System, they were at a similar risk of dying as compared to the normal weight people in that sample. And they're in fact at lower risk for dying of cardiovascular disease," Kuk says.

Many of these obese-but-healthy people had struggled to lose weight, but Kuk says that may not be the best approach for someone who eats well and is physically active, despite carrying some extra kilos.

"There are healthy obese individuals, and these healthy obese individuals may not actually benefit from losing weight. Instead, we should focus on a healthy lifestyle that includes exercise and a good diet, and maybe these healthy individuals should stop focusing so much on losing weight and just focus on not gaining any more."

The Edmonton System was developed by researchers at the University of Alberta, and it is meant to be used alongside the traditional BMI scale. But perhaps because it is more complex than just using BMI, EOSS has been slow to gain traction.

Jennifer L. Kuk's study is publised in the journal Applied Physiology, Nutrition and Metabolism..

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（来源：VOA 编辑：崔旭燕）