Healthy fats.  Fats are nature's way of packaging a large amount of calories into a small space.  While butter, cream, and other animal-based fats will add calories, fats from plant-based sources like nuts or fruits and vegetables like olive oil or avocado are healthier for your heart.  Try adding an extra spoon or two of olive oil to your serving of soups, pastas, or other cooked foods.  Sprinkle nuts or seeds like sunflower or pumpkin on salads or soup.  Avocado slices go well on salads or in sandwiches.

In addition to trying these suggestions, it may be helpful to meet with a nutritionist who can tailor a diet for you.  You may also need to discuss with your healthcare provider whether you should take any nutritional supplements which are commercially available.