This diet provides adequate water, 500–1000 kcal as simple sugar, and some electrolytes. It is fiber free and requires minimal digestion or intestinal motility.
A clear liquid diet is useful for patients with resolving postoperative ileus, acute gastroenteritis, partial intestinal obstruction, and as preparation for diagnostic gastrointestinal procedures. It is commonly used as the first diet for patients who have been taking nothing by mouth for long periods. Because of the low calorie and minimal protein content of the clear liquid diet, it is used only for short periods.
The full liquid diet provides adequate water and can be designed to provide adequate calories and protein. Vitamins and minerals—especially folic acid, iron, and vitamin B6—may be inadequate and should be provided in the form of supplements. Dairy products and soups are used to supplement clear liquids. Commercial oral supplements can also be incorporated into the diet or used alone.
This diet is low in residue and can be used in many instances instead of the clear liquid diet described above—especially in patients with difficulty chewing or swallowing, with partial obstructions, or in preparation for some diagnostic procedures. Full liquid diets are commonly used following clear liquid diets to advance diets in patients who have been taking nothing by mouth for long periods.
Soft diets are designed for patients unable to chew or swallow hard or coarse food. Tender foods are used, and most raw fruits and vegetables as well as coarse breads and cereals are eliminated. Soft diets are commonly used to assist in progression from full liquid diets to regular diets in postoperative patients, in patients who are too weak or those whose dentition is too poor to handle a regular diet, in head and neck surgical patients, in patients with esophageal strictures, and in other patients who have difficulty with chewing or swallowing.
The soft diet can be designed to meet all nutritional requirements.