If you are underweight or want to replace pounds lost due to illness or another reason, you must increase your daily caloric intake so you are taking in more calories than you are burning. Unfortunately, your appetite is not limitless, which means you need to make every meal and snack count and concentrate on substituting high-calorie, nutritious items for foods that are low in calories. The United States Department of Veterans Affairs notes that the best way to add calories to your diet is to increase the amount of fat and carbohydrates in your meals.
Snack on lightweight, high-calorie foods between meals. Nutritious snacks that are high in calories but not so filling they will affect your ability to eat meals include avocado, olives, cream cheese with crackers, and fresh fruit.
Choose high-calorie fruit juices over water. The University of Virginia recommends cranberry juice, peach or pear nectar, orange juice, lemonade, and fruit-flavored drinks such as Kool-Aid and Hawaiian Punch.
Eat foods high in carbohydrates and calories with every meal. The VA suggests including both simple sugars and starches in your diet. Simple sugars, such as honey, syrup and dried fruit, make great additions to breakfast and snack time, while muffins, oatmeal, potatoes, rice and other starches work well between meals or as side dishes.
Add dry milk powder, protein powder or flavored syrups to milk to increase your caloric intake. MayoClinic.com suggests adding ground flaxseed to milkshakes for a nutritional, high-calorie drink.
Use butter or margarine when cooking and on noodles, rice, vegetables, crackers and breads. If you suffer from high cholesterol or high blood pressure or have other risk factors for heart disease, speak with your doctor about increasing the amount of butter in your diet. Butter is high in sodium, saturated fat and cholesterol.
Put mayonnaise on both sides of your bread when making sandwiches. Mayonnaise contains about 100 calories in a 1 tbsp. serving, according to Drugs.com.
Increase the amount of eggs, nuts, seeds, peanut butter, cheese and jellies in your diet. These foods are high in calories and make calorie-laden additions to sandwiches and salads.
Drink ready-made dietary supplements for weight gain, such as Ensure, Boost or similar drinks, between meals or before going to bed.