Health experts explain there are only two ways for people to lose weight: Either ingest fewer calories or burn more of them off. And a healthy regimen requires both diet and exercise.

But, for academic health researchers, there is still a question: Which is more important, to shed fat or become more physically active? The Journal of the American Medical Association dubs the question "fatness versus fitness," and is publishing two studies that answer the question with a contradiction.

One study, led by University of Florida researcher Timothy R. Wessel, examined whether obesity or low physical activity better indicated the risk of heart disease in women. The findings caught many off guard. While obesity is certainly linked to heart disease, a person's level of exercise far better predicted heart attacks and heart disease.

Indeed, the study found that of the 936 women studied, obesity predicted 26 per cent of the cases of heart disease that emerged in the group. Meanwhile, low physical activity predicted 46 per cent of the cases of heart disease.

Wessel said they measure physical fitness as the ability to perform day to day activities, "like running for a bit, climbing a flight of stairs."

"These results suggest that fitness may be more important than overweight or obesity for cardiovascular risk in women," write the study's authors.

The statement might sound more authoritative if an article in the same issue of the journal didn't claim another kind of risk for obesity.

This study, led by Amy R. Weinstein, formerly of Brigham and Women's College Hospital in Boston, found that obesity was far worse for women than low physical exercise, as obesity can lead directly to diabetes.

This study examined 37,878 women who had no history of heart disease of diabetes. The researchers then followed up with the women seven years later. The women were also divided into three categories:

• Normal, defined as a body-fat ratio of less than 25;
• Overweight, defined by a ratio of 25 to less than 30;
• And obese, which has a ratio 30 or higher.

Compared with normal-weight individuals, overweight individuals had a 3.2 times increased risk for diabetes; obese individuals, a 9.1 times increased risk. The risk associated with low physical activity was marginal in comparison.

"We observed a modest reduction in the risk of diabetes with increasing physical activity level compared with a large increase in the risk with increasing BMI," the authors write. "These findings underscore the critical importance of adiposity [level of fat content] as a determinant of type 2 diabetes."

Fit vs. fat

So what does that tell you, a regular person simply trying to live disease free for as long as you can? Is it more important to eat lettuce meals three times a day, or to run three hours a day? Should you concentrate on how fat you are or how fit you are?

Well, according the editorial in the journal, fitness is most often the missing ingredient for the many of us who hop around from one miracle diet to another in an attempt drop weight. "In essence," write the journal's editors, "physical activity is the common denominator for the clinical treatment of low fitness and excess weight, making the 'fitness versus fatness' debate largely academic.

Doctors say women need 30 to 60 minutes of moderate exercise most if not every day of the week. And other studies indicate that 60 per cent of Canadian women don't get enough exercise to either stay fit or lose their fat.

"The treatment is exactly the same," says Dr. Robert Reid. "The solution to low levels of fitness and high levels of body weight is more physical activity."