The primary function of appetite is to control adequate energy intake in order to meet an organism's metabolic requirements. The interplay between hunger, appetite stimulation and food intake is tightly regulated by the central nervous system and conditioned by numerous inherently biological as well as acquired social and cultural phenomena. Appetite is closely linked to individual behaviour, thereby affecting energy intake as well as qualitative food structure and represents a basis for possible therapeutic intervention in individuals with impaired appetite regulations. This book presents several perspectives on appetite regulation in humans and animal models. The importance of understanding altered appetite regulation in cancer is highlighted as well as the effects of exercise on appetite. Finally, this book also presents new research into the role of genetic variability in ghrelin in dietary composition.