This book provides theoretical information on the assessment of nutritional status; obesity; underweight; anorexia and bulimia nervosa; diabetes mellitus; reactive hypoglycemia; metabolic syndrome; cardiovascular diseases; hypertension; gastrointestinal and thyroid diseases; cancer; liver, gallbladder, kidney, respiratory, bone and joint, and neurological diseases; allergies; enteral and parenteral nutrition; burns and wounds; medical nutrition therapy in bariatric surgery; nutrient–drug interactions; and test diets, and it explains medical nutrition therapy through case studies. Individually planned medical nutrition therapy is among the most important steps in the prevention and treatment of these diseases. With the aim of offering a resource that reflects the most up-to-date knowledge in these fields, most of the chapters have been written by active academics and clinicians who have clinical experience and closely follow scientific developments. The book has been prepared as a guiding resource for future dietitians and students receiving training in adult health and nutrition in disease.