When an individual does not get enough calories, micronutrients or proteins, it leads to malnutrition or nutritional deficiency. If this occurs during pregnancy or before the age of two, it can limit physical and mental development. Extreme undernourishment can lead to a thin body, short height, swollen legs and abdomen and low energy levels. The symptoms of micronutrient deficiencies are dependent on the nutrients absent. Malnutrition can have two manifestations, which are protein-energy malnutrition and dietary deficiencies. Kwashiorkor and marasmus are two severe forms of protein-energy malnutrition. Lack of iron, vitamin A and iodine results in dietary deficiencies. Severe malnutrition is treated by managing body temperature and low blood sugar, gradual feeding and addressing dehydration. Routine antibiotics are recommended to prevent infections. This book attempts to understand the various nutritional deficiencies, their diagnoses and treatment strategies. The various studies that are constantly contributing towards advancing the understanding of such deficiencies are examined in detail. With state-of-the-art inputs by acclaimed experts of this field, this book targets students and professionals.