Fat has a bad reputation in modern society despite being an essential part of our health and well-being. Across the animal kingdom, fat plays all sorts of vital roles in energy storage and insulation for migration, breeding and mating. Written by an expert in the field, this intriguing popular science book fills the gap between unscientific comments about dietary fats, weight control and the health hazards of high- or low-fat diets found in magazines; and technical medical reports about lipid biochemistry and obesity in animals and humans. It explains in clear, nontechnical language where fats come from and how the body handles them; the natural roles of fats; and the biology of feasting and fasting, and fattening and slimming in wild animals as well as people. All readers with an interest in fat and its uses and manifestations will find this book an enjoyable and informative read.