Scientists have developed a new way to measure whether a person is too fat without having people step on the scale.

The new measure, called the Body Adiposity Index, or BAI, relies on height and hip measurements, and it is meant to offer a more flexible alternative to body mass index, or BMI, a ratio of height and weight, U.S. researchers said on Thursday.

BMI has been used to measure body fat for the past 200 years, but it is not without flaws, Richard Bergerman of the University of Southern California, Los Angeles, and colleagues wrote in the journal Obesity.

While there are other, more complex ways to measure body fat beyond simply stepping on a scale, BMI is widely used both by researchers and doctors.

It is calculated by dividing weight in kilograms by height in metres squared. A person who is 5 feet 5 inches tall is classified as overweight at 150 pounds (68 kg) and obese at 180 pounds (82 kg).

But there is a lot of wiggle room in that calculation.

For example, women and men with the same BMI might have very different levels of extra flab. BMI numbers cannot be generalized across different ethnic groups or used with athletes, who have extra lean body mass.

Better than a BMI? New obesity scale proposed

Who are you calling fat? Canadians may be losing the battle of the bulge, but were still slimmer on average than our supersized cousins to the south.

A new Statistics Canada survey found that between 2007 and 2009, 24.1 per cent of adults in Canada were obese. In that U.S., that number was 34.4 per cent.

The gap was widest for women: 23.9 per cent of Canadian women qualified as obese, compared to 36.2 per cent of American women. Of Canadian men, 24.3 per cent were obese, while 32.6 per cent of American men tipped the scales.

But Canadians have no reason to feel smug about their comparative lack of bulk, said one obesity doctor.

Dr. Arya Sharma, professor of medicine and chair for cardiovascular obesity research and management at the University of Alberta, said Canada is eating its way into a public health crisis.

“We’re not where the Americans are yet, but the numbers are still very alarming,” he said. “When you consider the medical costs of obesity, of treating related cases of diabetes, heart disease, hip and knee replacements, its clear that we have a serious problem.”

Girth of a nation: Canada trails U.S. in obesity rates