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Moderate weight loss improves heart health

Research at Washington University School of Medicine shows that losing even a small amount of weight can improve heart and vascular health

March 31, 2011

Victor Davila-Roman, MD, and Lisa de las Fuentes, MD

It may not be easy or pleasant, but weight loss has more benefits than looking good in a swimsuit.

Losing even a little weight can greatly improve heart and vascular health, boost heart function, lower blood pressure and improve metabolism.

A research program at Washington University School of Medicine is dedicated to understanding the complex relationship between weight and heart health; its work shows that weight-loss benefits can last even if some of the weight returns, and that the effort can not only prevent but reverse significant health problems.

In recent studies of obese people, Washington University researchers followed patients in a weight-loss program and demonstrated that four key measures of heart and vascular health improved in those who lost weight, including the heart’s pumping ability, its ability to relax, the thickness of the heart muscle tissue and the thickness of the carotid artery walls.

The benefits continued over many months, even after an individual stopped losing weight and regained a few pounds.

Obesity and the heart

“An obese person requires a heart that is able to pump greater amounts of blood, so the chamber size—the actual cavity of the heart—enlarges, and the muscle gets thicker as well,” says Lisa de las Fuentes, MD, a Washington University cardiologist. “Over time in some individuals, the heart cannot compensate, and after a while, it begins to lose some of its ability to relax or its ability to pump blood to the rest of the body. Both can lead to heart failure.”

De las Fuentes says it was important to evaluate whether moderate weight loss could improve heart health. When the study began, about one-third of the patients were being treated for high blood pressure. .

“Hypertension, or high blood pressure, is a huge public-health problem in the United States,” says  cardiologist Victor Dávila-Román, MD, director of the Cardiovascular Imaging and Clinical Research Core Laboratory at Washington University. “Of the 65 million people with hypertension, between 25 percent and 50 percent have some evidence that their heart has been affected, so the presence of high blood pressure in so many of these subjects suggested that we needed to take steps to help them lower their blood pressure if we hoped to make their hearts healthier.”

Individuals in the study were instructed to eat either low-fat or low-carbohydrate diets— about 1,200 to 1,500 calories per day for women and 1,500 to 1,800 for men.

Both groups experienced similar amounts of weight loss and similar improvements in heart and vascular measurements. Subjects lost an average of 22 pounds, which represented about 10 percent of their body weight, according to de las Fuentes. Interestingly, she says the cardiovascular benefit didn’t appear right away, lagging behind weight loss. In fact, the greatest improvements in heart function didn’t come until six to 12 months after the study began, in spite of the fact that beginning at about six months, many of the participants began slowly to regain some of the weight they had lost.

Benefits through weight loss and regain

Although the average weight loss was more than 20 pounds, by the time two years had passed, most participants weighed only about nine pounds less than they had at the start of the study. Even though they regained some weight, they still retained much of the heart and blood vessel benefit related to their weight loss.

De las Fuentes says that although it’s possible that those beneficial effects would eventually end if people returned to their previous weight, it is clear from the study that the benefits of losing weight last for a long time.

Other research suggests that when body fat collects in the liver people experience serious metabolic problems such as insulin resistance, which affects the body’s ability to metabolize sugar. They also have increases in the production of fat particles in the liver that are secreted into the bloodstream and increase the level of blood lipids, or fats, such as triglycerides. High levels of these types of fats can increase heart disease risk.

But as de las Fuentes and Dávila-Román learned with heart health, many of the metabolic problems associated with fat in the liver also can be slowed, or even reversed, with weight loss.

Samuel Klein, MD, the William H. Danforth Professor of Medicine and Nutritional Science, says weight loss can make a big difference in heart health, particularly in those with high levels of fat in their liver.
Samuel Klein, MD, the William H. Danforth Professor of Medicine and Nutritional Science.

“It’s completely reversible,” says Samuel Klein, MD, director of Washington University’s division of geriatrics and nutritional science. “Calorie restriction and minimal weight loss can markedly reduce fat content in the liver. In fact, as little as two days of calorie restriction can cause a large reduction in liver fat and improvement in liver insulin sensitivity.”

Klein says people who are obese but don’t have high levels of fat in the liver should be encouraged to lose weight, but those with elevated liver fat are at particularly high risk for heart disease and diabetes and need to be treated aggressively to help them lose weight, because dropping a few pounds can make a big difference.

Losing 10 percent

Looking at the big picture, the researchers say losing 10 percent of your body weight may be enough to do the trick. For some that may involve losing 15 or 20 pounds. But even those who can’t lose that much weight can still benefit from smaller amounts of sustained weight loss.

“Losing 20 or so pounds might seem daunting, but we’ve shown that even a modest weight loss can yield heart and vascular benefits,” de las Fuentes says. “It’s important to realize that you can choose goals that are attainable and work towards those goals progressively. Even small amounts of weight loss seem to improve metabolic function and hypertension, as well as enhance heart pumping and relaxation, while causing the heart tissue and blood vessel walls to get thinner. Cholesterol and triglyceride levels usually improve, too.

Other studies of weight loss and its effects on metabolism and cardiovascular function currently are under way. For more information, visit Volunteer for Health or call (314) 362-1000.

A version of this story appears in Innovate, a magazine published by Barnes-Jewish Hospital and Washington University Physicians highlighting the latest clinical and research advancements offered by these two institutions.