This is a unique book which critically summarizes the current scientific knowledge concerning manifestations, mechanisms, consequences and prevention of dysfunctions of metabolism of fat, as well as the main known functional food and medicinal plants which can be and which cannot be used for prevention and treatment of obesity. The provenance, biologically active molecules, positive and adverse side-effects on health, influence on obesity and potential applicability of tea, chicory, Garcinia cambogia, Hoodia gordonii, chia, Irvingia gabonensis, apple cider vinegar, coffee, konjac/glucomannan, flaxseed, mulberry, oat, sweet and hot peppers, carob, cinnamon, plum, Cissus quadrangularis, Stevia rebaudiana, Yacon and ginger are described in details. In addition, less-known plants and plant molecules, as well as their combinations considered applicable for obesity treatments, are listed. It is demonstrated that more than half of the plant-based anti-obesity products available on the market are not properly clinically tested, or such tests, when performed, provided negative results. In addition, the author provides the reader with some practical advices and tips to combat obesity with healthy lifestyle. This book combines deep scientific analysis of physiological processes and popular form of their description. Such form enables to use this knowledge and advices for scientists, doctors, producers, distributers and consumers of functional food and medicinal plants, as well as for the common readers interested in healthy nutrition and life style.