The enigma of human energy has been cracked. Biologist Guy Brown offers the first popular introduction to the cutting edge science of bioenergetics, one that provides a new understanding of the energy of life. We all know that something is happening to our energy levels on a sugar 'rush,' or a coffee 'high,' or following that afternoon nap, but now everyone can understand the smoothly operating human-energy machine, thanks to Brown's lucid overview of how energy courses through us at both the micro level of our cells and the macro level of our behavior. At the micro level, the fundamental energy of our bodies is the frenetic movement within our cells that is powered by body heat. The nucleus, the mitochondria, and all ten thousand tiny bimolecular machines that fabricate and transport molecules around the cell do not sit still within the cell membrane but move about as if they were bubblegum balls in a vibrating gum machine. This movement puts every element of the cell in contact with every other every few seconds and enables the energy of the cell to flow. The energy comes from mitochondria, those strange, genetically distinct little beasts that heat our bodies and consume all the food we eat and oxygen we breathe. Brown has completed breakthough work on mitochondria and explains how they invaded our cells hundreds of millions of years ago. In the last few years, he and his colleagues have shown how these invaders wield the power of life or death over our every cell, over our very lives. The carbohydrates, fats, and proteins we eat constitute mitochondria's main fuels, but our brains run only on glucose -- a peculiar and even toxic chemical when there is too much of it inour blood, as any diabetic knows well. This energy source of the mind is in very limited supply in our bodies because we can store so little of it. Brown suggests that we tend to eat too much fat because we are designed to stop being hungry when we've eaten enough of the carbohydrates from which we make glucose. Eating fat doesn't make us feel 'full' as quickly or in the same way. For this reason, in the macro world of affluent societies, we must remind ourselves of the importance of a relatively high-carbohydrate, relatively low-fat diet. Brown explores the energy dynamics of our athletic limits and our excited minds. He shows the strengths of mitochondria-rich brown muscle and the high-speed power of mitochondria-poor white muscle. Sex, which surprisingly begins as electrical energy in the brain's hypothalamus cell nuclei, increases heart rate, blood pressure, respiration rate, and muscle tension, quickly drenching the body in a shower of energy, culminating in orgasm. Ultimately, Brown reveals all the processes of mind and body to be flows either of short-term or long-term energy that are most efficient when we follow the simple plan of a balanced diet and regular exercise. Built on a foundation of original research, a study of what energy has meant historically, and the up-to-the-minute perspective of the Brown Laboratory in the celebrated halls of biochemistry at Cambridge, this book is a treasure chest of human science for those interested in how our vital force works. Intriguingly, Brown concludes that it is more important to base our lives on the science of long-term and short-term energy levels than on monitoring our calorie intake or even our bank balance. Whether ornot we follow this advice, here is an entertaining and scientific owners' manual for the human body that celebrates 'the creator and destroyer of all things,' 'The Energy of Life.'