A Randomised, Controlled Trial of a Low-energy Diet for Improving Functional Status in Heart Failure With PRESERVED Ejection Fraction Preserved Ejection Fraction

Inclusion Criteria: 1. Established clinical diagnosis of heart failure with preserved ejection fraction HFpEF (EF\>45%) made by a cardiologist or a primary care physician with heart failure expertise, or a heart failure nurse 2. Clinically stable for ≥ 3 months (no admissions to hospital) 3. Obesity (BMI ≥30kg/m2 if white European or ≥27kg/m2 if Asian, Middle Eastern or Black ethnicity) 4. Age ≥18 Exclusion Criteria: 1. Inability to walk/undertake 6-minute walk test 2. Inability to follow a low-energy MRP 3. HFpEF due to infiltrative cardiomyopathy (cardiac amyloidosis or sarcoidosis), genetic hypertrophic cardiomyopathy, restrictive cardiomyopathy/pericardial disease or congenital heart disease. 4. Recovered EF (previous EF \< 40%) unless reduced EF was in context of tachycardia induced cardiomyopathy (eg AF/Aflutter). 5. Known heritable, idiopathic or drug-induced pulmonary arterial hypertension 6. Severe chronic obstructive pulmonary disease (FEV1\< 1.0L) 7. Severe primary valvular heart disease 8. Anaemia (Hb\<100g/L) 9. Severe renal disease (eGFR \< 30 ml/min/1.73 m2) 10. Weight loss \> 5kg in preceding 3 months. 11. Symptomatic gallstones (including biliary colic) or cholecystitis within last 3 months 12. Active substance abuse (drugs or alcohol) 13. History of bariatric surgery in the last 3 years 14. Active illness likely to cause change in weight 15. Women who are pregnant or are considering pregnancy 16. People currently participating in another clinical research trial that is likely to affect diet or weight change. 17. History of a severe mental illness including an eating disorder 17\. Individuals with a diagnosis of Type 1 diabetes mellitus.