Sometimes your doctor may prescribe a special diet before or after certain procedures, tests or surgeries or if you have certain digestive disorders. Here is an overview of a few commonly prescribed diets.

Clear liquid diet

A clear liquid diet is often used before tests, procedures or surgeries that require no food in the stomach or intestines, such as colonoscopy. It may also be recommended for people with certain digestive problems, such as diverticulitis, or after certain types of surgery. Clear liquids are easily digested and leave no undigested materials in the intestinal tract.

A diet of clear liquids helps maintain vital body fluids and provides some important minerals, such as sodium. It also provides some energy. However, a clear liquid diet is not adequate in calories and nutrients and shouldn't be used for more than a few days without direct medical supervision.

Foods allowed

• Plain water
• Fruit juices without pulp, such as apple juice, grape juice or cranberry juice
• Broth (bouillon or consomme)
• Gelatin
• Popsicles without bits of fruit or fruit pulp
• Tea or coffee with no cream

Foods to avoid

Any foods not on the foods allowed list.

Low-fiber diet

A low-fiber diet may be prescribed for people with certain digestive problems, such as diverticulitis or inflammatory bowel disease, or after surgery. Fiber is the part of fruits, vegetables and grains not broken down by the body that contributes to stool. A low-fiber diet limits the amount of undigested materials that must pass through the large intestine and may help control abdominal cramping and diarrhea in some cases.

Foods allowed

• Enriched white bread
• White rice
• Plain pasta, noodles or macaroni
• Cereals with no more than 1 gram of dietary fiber per serving
• Most canned or cooked fruits without skins, seeds or membranes
• Raw fruit without skin or membranes
• Fruit juice with little or no pulp
• Canned or well-cooked vegetables without seeds, hulls or skins — such as carrots or string beans
• Tender meat, poultry and fish
• Eggs
• Smooth peanut butter — up to 2 tablespoons a day
• Milk, yogurt or cheese without seeds or nuts
• Fats, oils and dressings without seeds
• Desserts with no seeds or nuts

Foods to avoid

Note: Limit fruits and vegetables to one to two servings a day. One serving is 1/2 cup or one small whole fruit.

• Whole-grain breads, cereals and pasta
• Brown or wild rice
• Dried fruits
• Raw fruit with skin or membranes, such as oranges and grapefruit
• Pears
• Raw vegetables
• Dried beans or peas
• Baked beans
• Luncheon meats and cheese with seeds
• Chunky peanut butter
• Seeds and nuts
• Coconut
• Popcorn

Low-residue diet

A low-residue diet may be prescribed to reduce the size and number of stools, such as after gynecologic surgery. It may be used for a short time before transition to a low-fiber or regular diet.

The terms "fiber" and "residue" may be used interchangeably. But technically, they're not the same thing. Fiber is the undigested part of plants that remains in the intestinal tract and contributes to stool. Residue includes fiber and any other foods that may increase stool output.

A low-residue diet is similar to — but more restrictive than — a low-fiber diet. If you must stay on this diet for a long period, consult a registered dietitian to make sure your nutritional needs are being met.

Foods allowed

• Refined breads, cereals, crackers, chips and pasta with less than 1 gram of fiber per serving (Note: Ideally, look for products with zero grams of dietary fiber per serving.)
• White rice
• Vegetable juices without seeds or pulp
• Fruit juices with no pulp
• No more than 2 cups a day of milk, yogurt, pudding, cream-based soups and ice cream
• Tender meat, poultry, fish and eggs
• Oil, margarine, butter and mayonnaise
• Smooth salad dressings
• Cream sauces
• Broth-based soups and cream-based soups, strained
• Jelly, honey and syrup

Foods to avoid

• Whole-grain breads, cereals and pasta
• Whole vegetables and vegetable sauces
• Whole fruits, including canned fruits
• Yogurt, pudding, ice cream or cream-based soups with nuts or pieces of fruits or vegetables
• Tough or coarse meats with gristle and luncheon meats or cheese with seeds
• Peanut butter
• Salad dressings with seeds or pieces of fruits or vegetables
• Seeds and nuts
• Coconut
• Marmalade