Janell Grazzini Frantz, APRN, CNP, MSN, Mayo Foundation for Medical Education and Research DEAR MAYO CLINIC: My doctor told me that I have congestive heart failure and I have to change my lifestyle, including my diet. What kind of diet should I be on? ANSWER: When patients have congestive heart failure, their heart isnât able to manage fluid well, and it builds up in the body. This fluid can cause shortness of breath, swelling in the abdomen or legs, and fatigue. If this occurs, diuretics, or water pills, often are prescribed to remove the excess fluid. Your health care provider also will recommend that you restrict your sodium, or salt, intake.