Researchers found that among 25 healthy but overweight middle-aged adults, moderate weight loss appeared to restore some the heart's youthful elasticity -- making it easier for the heart to relax between contractions and refill with blood.

It did not appear to matter whether the weight loss was achieved through diet changes or exercise, the researchers report in the American Journal of Physiology.

"If individuals want to do something that's good for their heart, then my message to them is lose weight by the method they find most tolerable," Dr. Sandor J. Kovacs, the senior researcher on the study, said in a statement.

"They're virtually guaranteed that it will have a salutary effect on their cardiovascular system," said Kovacs, a professor of medicine at Washington University School of Medicine in St. Louis, Missouri.

As people age, their body tissue accumulates collagen fibers, which causes tissue-including heart muscle and arteries-to become more stiff. So over time, the heart starts to take a bit longer to relax between contractions and fill back up with blood.

Excess weight, obesity in particular, has been shown to affect the heart's elasticity as well. But while studies suggest that weight loss achieved by diet and exercise improves cardiac function, it hasn't been clear if the same is true if weight loss is accomplished using just one of these strategies.

So Kovacs and his colleagues looked at weight loss and heart function in 25 men and women who were overweight, but not obese. For one year, half of the participants cut their daily calories by about 12 percent, while the rest took up an exercise routine-doing activities like walking, running or cycling six days per week.