This document provides an overview of diet therapy for various diseases and surgical conditions. It discusses indications, contraindications and clinical implications of different diet types (e.g. clear liquid, full liquid, pureed) for diseases like diarrhea, constipation, peptic ulcers, and conditions requiring surgery of the mouth, throat, esophagus or gastrointestinal tract. Specific postoperative diets are outlined for surgeries like gastrectomy, intestinal surgery and cholecystectomy.