Unfit and Lean Have Fewer Cardiac Risk Factors Than Fit and Fat

Linda Little

November 22, 2005

Nov. 22, 2005 (Dallas) — Losing weight may be more important than exercise when it comes to being heart healthy in young adulthood, Rhode Island researchers reported here at the American Heart Association 2005 Scientific Sessions.

"It is better to be a normal weight than to be fat and fit," Charles Eaton, MD, professor of family medicine at Brown University Medical School in Pawtucket, Rhode Island, told Medscape. "There is a large population of Americans who are overweight. The question is whether it is better to lose weight or become fit."

Not surprisingly, this study showed that participants who were highly fit and had a normal body mass index (BMI) had the best risk factor profiles for coronary heart disease (CHD), while those with low fitness levels or who were overweight or obese had the worst profiles.

However, the researchers also found that low-fit normal weight participants had better risk profiles for CHD than those who were highly fit, but overweight or obese.

Researchers used cross-sectional data from the National Health and Nutrition Examination Survey (NHANES) and studied 2,178 young adults, aged 20 to 49 years, with different levels of fitness. All participants had blood work-ups for total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), glucose, insulin, fibrinogen, and homocysteine levels. Blood pressure, height, and weight were recorded using standard protocols. Fitness categories, based on the norms for age and sex, were used to define low, moderate, and high levels of cardiovascular fitness.

BMI was measured and categorized as normal (< 25 kg/m 2), overweight (25 - 30 kg/m 2), and obese (> 30 kg/m 2).

The researchers looked at the relationship between BMI level and cardiovascular
fitness level to determine whether it is better to be fat and fit or thin and unfit.

When comparing the group of participants who were obese/fit vs the group that was thin/unfit, researchers found statistically significant differences between groups in the TC/HDL-C ratio ( P = .0001) as well as HDL-C ( P = .0078), TC ( P = .0598) and non-HDL-C ( P = .0082) levels.

There also were trends toward differences in systolic blood pressure and white blood counts in the obese/fit vs the thin/unfit, but the differences did not reach statistical significance (120 mm Hg vs 112 mm Hg, respectively; P = .0869; and 7.24 vs 6.23, respectively; P = .0869).

There were no significant differences in the homeostasis model assessment (HOMA) index, a marker for insulin resistance, or in homocysteine or diastolic blood pressure levels between the two groups.

While this was a cross-sectional study that measured risk factors at one time point, the findings show that for most markers it was better to be thin and fit than fat and unfit, Dr. Eaton said. "High fitness and normal BMI subjects had the best cardiovascular disease risk factors. Those who were obese and unfit had the worst cardiovascular risk factors."

But, he noted, the study results also suggest that it is better to be normal weight and unfit than obese and fit.

The results, however, are not in line with other studies on this subject and other preliminary studies have had mixed results. This study, he said, probably would have required a larger number of participants to reach statistical significance for some markers.

Nevertheless, "This study adds to the dialogue that weight is more important than fitness," he told Medscape. "If you are overweight it is better to get down to normal weight than be overweight and fit."

In addition, the data, he cautioned, are preliminary and no firm clinical statement can be made at this time. Dr. Eaton called for further longitudinal studies to determine whether dieting or exercise will bring more beneficial results in reducing CHD risk factors in the overweight or obese population.

"This study raises important questions as to whether or not being fat and fit is okay," Robert Eckel, MD, president of the American Heart Association and professor of medicine at the University of Colorado Health Science Center in Denver, told Medscape. "The biomarker report here is not as favorable as that previously reported.

"Being both normal weight and fit remain the best recommendation for prevention of cardiovascular disease and diabetes," he added.

AHA 2005 Scientific Sessions: Abstract 3611. Presented Nov. 13, 2005.

Reviewed by Ariana Del Negro

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