A new study shows that people who are obese can reverse some early heart and blood vessel dysfunction by adopting a healthy lifestyle and losing weight. But exercise alone, without weight loss, does not appear to be enough to improve cardiovascular function.

Dr. Chiew Y. Wong of the University of Queensland in Australia and colleagues had 106 obese men and women with no cardiovascular disease complete an eight-week lifestyle intervention program. Sixty-two cut their calorie and fat intake and exercised, while 44 exercised but did not change their diet.

Forty-eight of the study participants lost an average of 4.5 percent of their body weight, while the remaining 58 kept their weight stable or gained weight.

Among those who lost weight, the researchers noted improvements in their arteries' response to changes in blood pressure, as well as a 15 percent improvement in peak VO2, a measure of how well the body uses oxygen during exercise.

The more weight people lost, the greater their improvements in blood vessel function and fitness. People who lost weight also showed some improvement in their left ventricular function.

While the men and women who didn't lose weight did show improvements in peak oxygen uptake -- a measure of how well the body uses oxygen -- no significant changes were seen in their heart or blood vessel function.

This study "supports the argument that increasing cardiorespiratory fitness alone is not sufficient to produce the same cardiovascular benefits," the researchers conclude.

SOURCE: American Journal of Cardiology, December 15, 2006.