Book excerpt: This book provides a detailed summary of the therapeutic benefits of natural extracts from medicinal plants, mushrooms, algae, fungi and sponges and their role in the prevention and treatment of obesity and diabetes, offering readers a solid introduction to obesity and diabetes as well as current treatment models. In addition, it examines how genomics and multi-omics approaches have revolutionized our understanding of these diseases, and discusses the role of microbiome-host interactions, probiotics, prebiotics and the future of metabolic phenotyping. Focusing on the pharmacokinetics of anti-obesity and anti-diabetic phytochemicals, their bioavailability in the respective target tissues and their elimination times, the book also describes the nanoformulations of phytochemicals and herbal extracts. Lastly, it presents an overview of the advances in clinical studies on the use of herbal and mushroom extracts in obesity and diabetes management. Given its scope, this book is useful not only for researches in the field but also for students studying nutrition, food sciences, plant sciences or pharmacology, as well as for health professionals and practitioners.