Dr. Duck-chul Lee (University of South Carolina, Columbia) stated that, "We know that people who exercise will lose weight and improve their fitness, but in the real world, some people don't lose weight even though they might gain some fitness." "Some of these people might stop exercising because they expected to lose weight and haven't, but this study shows that they should also be aware about their changes in fitness. Even though they don't lose weight, if they increase their fitness, they can offset some of the negative effects of being overweight."
Lee noted that fitness and fatness are two variables that consistently change over time in individuals and that there are many diverse combinations of fitness and fatness in US adults. In fact, the "fit-fat" paradox has been demonstrated in some studies, showing that improvements in fitness can eliminate the harmful effects of fatness and suggesting that fit but fat individuals might not develop health problems.
In the ACLS analysis, 3148 healthy subjects underwent three medical examinations, with fitness levels assessed using maximal treadmill testing and fatness documented with body-mass index (BMI) and skinfold measurements of percentage of body fat. During a six-year follow-up after the second medical examination, 752 subjects developed high blood pressure, 426 developed metabolic syndrome, and 597 developed hypercholesterolemia.
Individuals who maintained or improved their fitness levels had a 26% and 28% lower risk of developing hypertension, a 42% and 52% lower risk of developing metabolic syndrome, and a 26% and 30% lower risk of developing elevated levels of LDL cholesterol, respectively. These reductions were observed after adjustment for potential confounders and baseline fitness levels.
For those subjects who got fatter in follow-up, as measured by percentage of body fat, they had a 26%, 71%, and 48% higher risk of developing hypertension, metabolic syndrome, and hypercholesterolemia, respectively, when compared with individuals who lost weight. Similar results were observed when BMI was used as the criterion for fatness levels.
Every 1-MET improvement in fitness was associated with a 7%, 22%, and 12% lower risk of developing hypertension, metabolic syndrome, and hypercholesterolemia, respectively, while every unit increase in percentage of body fat was associated with a 4%, 10%, and 5% increased risk of developing the cardiovascular risk factors.
Dr. Lee went on to say that, "In the real world, people change their fitness levels or fatness over time." "Fitness and fatness, not the baseline levels, but the changes over time, are both independently important to reduce cardiovascular disease risk factors."
In joint analyses, the researchers found that patients who had stable or increasing amounts of fatness in combination with loss of fitness had significantly higher rates of cardiovascular risk factors when compared with the reference group, that being individuals who gained fitness over time and lost fat. They did observe that losing fitness regardless of fat changes and getting fatter irrespective of the change in fitness levels were associated with a higher risk of developing metabolic syndrome. The adverse effects of getting fatter were attenuated slightly if fitness was maintained or improved, while declines in fitness could be offset by reductions in body-fat percentage.
"Maintaining or improving fitness levels and preventing fat gain are both important, independent of the changes of each other," said Lee. "Second, we found that the ideal combination is to improve fitness and prevent fat gain, but as long as individuals maintain fitness and fatness, they are not likely to be at higher risk of cardiovascular disease risk factors. Losing weight and gaining fitness is very challenging to the general population, but maintaining fitness and fatness are less so and more doable."
The results of the study, an analysis of the Aerobics Center Longitudinal Study (ACLS), a prospective study of individuals who received preventive medical examinations, are published online February 6, 2012 in the Journal of the American College of Cardiology.