The Centers for Disease Control and Prevention (CDC) reports more than 80 percent of patients with a common type of heart failure are overweight or obese. Exercise intolerance is the primary symptom of this chronic condition, called heart failure with preserved ejection fraction (HFPEF). What's more is a lack of physical activity can be a major determinant to a patient's quality of life. However, new research published in JAMA suggests calorie restriction could improve both exercise capacity and quality of life.

Prior research has shown heart failure patients who exercise regularly can increase their tolerance of physical activity without shortness of breath, a commonly reported symptom. But results from a clinical trial led by researchers at Wake Forest School of Medicine found that dieting can have this same effect. It seems the combination of calorie restriction and exercise can greatly improve patients' health.

"Exercise has been proven to improve symptoms of shortness of breath," lead author Dr. Dalane Kitzman told Medical Daily. "Our new study suggests that weight loss does that as well."

Researchers collected and analyzed data from 100 older obese patients diagnosed with HFPEF. The participants were randomly assigned to 20 weeks of diet, exercise, diet and exercise, or a control group; Wake Forest prepared and provided calorie-restricted meals for patients. Researchers measured patients' oxygen consumption in order to determine their exercise tolerance, while also administering a survey to measure their quality of life.

In the diet group, body weight decreased by 7 percent; by 3 percent in the exercise group; by 10 percent in the exercise and diet group; and by 1 percent in the control group. They found that exercise capacity increased significantly in those enrolled in the exercise and diet groups, with the combination of diet with exercise making an even greater impact.

"Improvements in exercise capacity with diet were at least as large as that due to exercise," Kitzman said. "[T]he combined effect of [diet and exercise] was so large; it was larger than most medications for other types of heart failure."

Kitzman and his team observed the increased ability to exercise was positively correlated with the change in the percentage of lean body mass.

"Our data indicate that it was due to reducing the amount of fat in the body, particularly in the leg muscles, and decreasing inflammation that is caused by excess fat," Kitzman added.

Researchers say more studies are needed to determine whether these changes are associated with clinical events, especially with the reported "heart failure obesity paradox;" in which fewer deaths occurred in overweight or obese individuals with heart failure.

Kitzman said the next step is to determine whether these improvements can be maintained "and whether they will translate into improved survival."

Source: Kitzman D, Brubaker P, Morgan T, et al. Effect of Caloric Restriction or Aerobic Exercise Training on Peak Oxygen Consumption and Quality of Life in Obese Older Patients With Heart Failure With Preserved Ejection Fraction. JAMA. 2016.