Diet vs. Exercise: Which Lowers Death Risk More?

Diet vs. Exercise: Which Lowers Death Risk More?

We've all heard it before: In order to maintain a healthy heart and decrease your risk of dying from cardiovascular issues, it's all about working out and watching your weight. But which of the two has a bigger impact?

According to a new study, fitness may trump diet.

The findings, published in Circulation: Journal of The American Heart Association, suggest that maintaining or improving fitness levels can reduce death risk -- even after researchers accounted for confounding factors, like changes in body mass index (the commonly used measurement of a person's weight relative to his or her height).

"Fitness loss with age is associated with a higher risk of all-cause and CVD [cardiovascular disease] deaths, after controlling for weight change," said Dr. Duck-chul Lee, PhD, the study's lead researcher and a physical activity epidemiologist at the University of South Carolina's Arnold School of Public Health.

"However, weight, BMI or even percent body fat change were not associated with death risk," he continued.

In the new study, Lee and his co-authors looked at more than 14,000 men -- most of whom were white and middle or upper class. They had an average age of 44, were slightly overweight (BMI of 26) and were relatively fit.

For every unit of increased fitness, which researchers gauged using METs or Metabolic Equivalents (basically, a measurement of how hard your body is working based on a treadmill test) over six years, they saw a 19 percent lower risk of heart disease and stroke-related deaths and a 15 percent lower risk of death from any disease. The authors followed up with people for slightly more than 11 years.

"What this study was trying to determine is what's more important for cardiovascular disease -- fitness or fatness?" said Dr. Marc Gillinov, a staff surgeon in the department of thoracic and cardiovascular surgery at the Cleveland Clinic and author of the forthcoming book "Heart 411." "Its conclusion is that overall fitness appears to be more important than BMI, more important than fatness, when it comes to determining whether you're going to be at risk for dying from CVD."

The message, Lee said, is that we may need to focus more on maintaining or improving fitness rather than worrying too much about weight gain -- at least in terms of public health. He said efforts should focus on the importance of regular exercise and upping daily activity levels, by doing small things such as walking the dog and taking the stairs instead of the elevator.

However, Lee cautioned that because the study looked at mostly normal or slightly overweight men, it does not make clear whether the results would apply to severely obese people. Generally, a BMI of 18.5 to 24.9 is considered normal, 25 to 29.9 is considered overweight and 30 or higher is considered obese.

Gillinov echoed the idea that the new findings should not be extrapolated for people who are considered obese.

He added that the research may have greater implications for the scientific community than for individuals -- for most people, he said, their fitness level tends to be linked to their weight. What the finding does is underscore the importance of exercise when it comes to health -- a message he said can be underrepresented in our thinking on these issues.

"The message is that you are doing yourself a lot of good with exercise," he said. "If you're someone who's fit but is finding it hard to drop those last five to 10 pounds, don't beat yourself up about it too badly. And if you're someone who's overweight but active, I'd say keep working on it, because you're doing some good. This is a reminder that fitness is really important."

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