There could come a time when it’s too late to lose weight
Study • While losing weight helped younger mice reverse heart damage, it didn’t do much for older mice that lost a similar amount of weight.
Published: March 5, 2013 10:47AM
Updated: March 5, 2013 09:20AM

Losing weight may not universally reverse heart damage caused by obesity, suggests new research in mice. Researchers at Johns Hopkins University School of Medicine found that younger mice experienced greater improvement in heart function after losing weight than older mice that lost a similar amount of weight, which may mean the protective effect of weight loss on the heart is stronger for those who slim down sooner rather than later.

Although the findings are in mice, they offer clues as to what scientists should look for when exploring the effects of obesity and weight loss on heart function, says senior study author Lili Barouch, MD, a cardiologist and assistant professor of medicine at Johns Hopkins.

“I’m certainly not saying if you’re older and overweight, don’t bother, but the key finding was that in younger animals, there was more benefit,” Dr. Barouch says. “The longer you wait, it gets harder to see the benefits.”

For the study, published in the Journal of Cardiovascular Translational Research, Barouch and colleagues put two groups of mice — an older group and a younger group — on the same calorie-restricted diet. The younger mice were 2 months old, comparable to young adulthood in humans; and the older mice ranged from 6 to 7 months old, comparable to middle age.

Because they tested only two mouse age groups, the researchers didn’t determine where in the mouse lifespan weight loss becomes less beneficial. Therefore they can’t tell how the research might apply to people.

How Weight and Weight Loss Change the Heart

Earlier studies have shown that obesity can stiffen heart muscle — preventing the heart from properly “relaxing,” which it must do in order to allow blood back into the heart after it squeezes it out to the rest of the body, Barouch explains. Heart muscle can stiffen in people with high blood pressure, abnormal sickness of the heart muscle, and/or obesity. If you’re overweight and have this problem, it can lead to congestive heart failure.

“I’ve been interested in studying obesity and heart disease for quite a long time,” says Barouch, “and I wanted to study how obesity affects heart function besides [being linked to] coronary disease. How it affects the heart in general, and what people can do to help reduce those problems, is the next step.”

Normal diastolic function — the part of the heart cycle where the heart muscle is actively relaxing to allow it to fill with blood — was restored in the younger mice in the study, and fat deposits in the heart muscle cells (called myocardial steatosis) diminished. In the older mice, levels of oxidative stress (free radical damage, or cell damage) got better, but stiffness and fat deposits didn’t go away.

Reversing Heart Damage from Obesity

Many other aspects of obesity observed in mouse studies also apply to people, says Barouch, so it makes sense that these findings would, too. “People should try to achieve ideal body weight and shouldn’t wait until later,” she believes. “Don’t wait until you develop problems.”

You might not notice or feel heart muscle stiffness or abnormal relaxation of the heart until it gets bad, Barouch adds: “They feel fine until it gets bad enough that they have congestive heart failure and it may not be reversible anymore.”

That’s what happened to one of Barouch’s current patients, William Wildberger, 52, of Curtis Bay, Md. Wildberger didn’t know Barouch back in October when he was diagnosed with congestive heart failure. Then 370 pounds, he surrounded himself with a good team of doctors, including cardiologist Barouch and his family doctor, and started making an effort to lose weight. He started with a 36-visit cardiac rehabilitation program and now goes to the gym six days week, sometimes twice a day. With the 60 pounds he’s lost so far, Wildberger is close to reversing his diabetes and returning his heart to normal rhythm, and he is no longer in heart failure.

“Why we wait so long until something like this happens to just start eating right to make us healthy, I just don’t know,” says Wildberger, but with every extra hole he adds to his belt, he’s glad he did.

That’s the takeaway of the study, says Barouch: “Take care of these risk factors before they develop into major issues.”

- Republished with permission from EverydayHealth.com