Heart failure with preserved ejection fraction (a measure of how well the left ventricle of the heart pumps with each contraction) is the most rapidly increasing form of heart failure, occurs primarily in older women, and is associated with high rates of illness, death, and health care expenditures. More than 80 percent of patients with heart failure with preserved ejection fraction (HFPEF) are overweight or obese. Exercise intolerance is the primary symptom of chronic HFPEF and a major determinant of reduced quality of life (QOL).