Though the hearts of overweight people may be stressed and out of shape, new research suggests that once a significant amount of weight is lost, either by dieting or bariatric surgery, the heart actually restructures into a healthier, more productive version of itself.
A year after weight loss, things were much improved for the formerly unhealthy hearts.
Researchers followed 37 obese participants as they lost an average of 45 pounds over a one−year period. The average Body Mass Index (BMI) for this group was 40 at the study’s outset – anything over 30 is considered obese. The team, led by Oliver J. Rider, used cardiac Magnetic Resonance Imaging (MRI) to evaluate various aspects of the overweight subjects’ hearts. They compared what they saw to the hearts of controls – normal weight participants whose average BMI was 21, which is right in the middle of the normal range.
The team found that the overweight individuals’ hearts showed some considerable differences from those of controls. In the former group, the muscles of the right and left ventricles (the chambers that pump blood out of the heart) were thicker, suggesting a general reduction in function. Additionally, the overweight participants’ hearts could not hold as much blood while at rest, or in diastole, and the walls of their aorta arteries were thickened.
The authors say that it made no difference whether participants had lost the weight by dieting or bariatric surgery. They point out that their findings help explain why mortality is reduced when people have lost significant amounts of weight.
The study was conducted by researchers at the University of Oxford and published in the August 18, 2009 issue of the Journal of the American College of Cardiology.