• Age ≥ 18 years old and ≤ 80 years old

• NYHA class I - III for at least 3 months

• Ejection fraction ≥ 50% by biplane 2D echo, 3D echo, or CMR.

• Echo findings of abnormal of indeterminant diastolic function or Right right heart catheterization (RHC) data: At rest: mean pulmonary capillary wedge pressure (PCWP) \> 15 mmHg. pulmonary vascular resistance (PVR) \< 3 Wood Units

• Stable medical therapy for at least 3 months as determined by the treating physician (no new cardiac or diabetic medications within 3 months of enrollment, or during enrollment) and dosage should be stable for 1 month prior to enrollment). Dose down titration and discontinuation is allowed during the study

• Dose of oral diuretics changes allowed, but must be stable for 1 week prior to randomization

• Body Mass Index (BMI) ≥ 25 and ≤ 50 or Type II Diabetes Mellitus or prediabetes as defined by fasting glucose of 100 - 125 mg/dL or glycated hemoglobin (A1C) 5.7-6.4%, or metabolic syndrome

• a. To meet definition of metabolic syndrome (NCEP ATPIII), 3 of the following criteria must be met: i. Abdominal obesity, defined as a waist circumference ≥102 cm (40 in) in men and ≥88 cm (35 in) in females ii. Serum triglycerides ≥150 mg/dL (1.7 mmol/L) or drug treatment for elevated triglycerides iii. Serum high-density lipoprotein (HDL) cholesterol \<40 mg/dL (1 mmol/L) in males and \<50 mg/dL (1.3 mmol/L) in females or drug treatment for low HDL cholesterol iv. Blood pressure ≥130/85 mmHg or drug treatment for elevated blood pressure v. Fasting plasma glucose (FPG) ≥100 mg/dL (5.6 mmol/L) or drug treatment for elevated blood glucose

• Ability to participate in exercise treadmill testing

• Ability to sign written consent