The human body must produce large amounts of energy for all physical and mental activities. With proper balance between health and fitness, the body will have no trouble meeting the energy requirements for optimal human performance. But where does this energy come from? The answer is both simple and complex. Basically, energy comes from the sun. Light energy from the sun comes to earth and is converted to chemical energy in plants through the process of photosynthesis. We eat the plants, and most of us eat animals that eat plants. The chemical energy we take in is converted to mechanical energy that fuels all our physical and mental activities. More directly, the energy produced by the body comes from the foods we eat. This energy is obtained from the basic macronutrients in food — carbohydrate, fat and protein. Though many foods contain all three, there’s usually a predominance of one of these in each food. Consider the following examples:
• Carbohydrates are predominant in bread, sugar, rice, pasta, fruit and fruit juice
• Fats are dominant in oil, butter, cheese, egg yolk.
• Protein is highest in meat, fish, poultry, eggs, cheese.
The majority of energy is produced from two of these food groups — carbohydrate and fat. Only a small amount, up to 15 percent of total energy, is produced from protein (by conversion of certain amino acids into glucose). All three macronutrients are converted into energy in two steps. First, they are broken down in the intestine and absorbed into the blood as glucose from carbohydrates, fatty acids from fats, and amino acids from protein
In the second step, the blood ultimately carries these elements to the cells, where the molecules of glucose, fatty acids and amino acids are further broken down. The hydrogen atom, the common building block of all three, is released as a result of further chemical breakdown. This atom contains one electron that is highly charged with energy. This electron is finally converted to a substance called ATP, which the body uses as energy. So, to get more specific, we could say the body’s energy comes from hydrogen’s electron. Carbohydrates, fats and proteins each have different amounts of hydrogen molecules, and, therefore, potential energy. Fats have by far the most hydrogen, one reason we can get much more energy from the fats in food. Fats can actually provide more than twice the potential energy you get from either carbohydrates or protein. Where does all this energy-generating activity take place? Mostly it is produced by your metabolism in the cells, especially in aerobic muscle fibers, which primarily use fat as a fuel. When these muscles are functioning optimally, you can derive even more energy from fat. In fact, up to 90 percent of your energy at any given time can come from fat, and the energy supply is virtually endless — the average lean person has enough stored fat to endure a 1,000-mile trek! The more energy you derive from fat the better your fitness, health and human performance. By improving your fat-burning system, you’ll improve metabolic efficiency and have more physical and mental energy. In addition, your body will store less fat, and you’ll maintain a more stable blood-sugar level because you won’t need as much sugar for energy. When you don’t produce the required amount of energy from fat, your body instead relies too heavily on sugar, usually producing fatigue. This common symptom, fatigue, is one of the most common complaints heard by doctors. It comes in physical and mental forms, or in a combination of both. Some people say they just can’t perform as they did when they were younger. But age is no excuse for a lack of energy. Physical fatigue may strike at a particular time of the day, or it may make you feel exhausted from the time you awaken. You may feel you don’t have the energy to do extra chores, go out at night or even get up in the morning. Mental fatigue is also common, making it difficult to think clearly or make decisions. This can affect any
16 • IN FITNESS AND IN HEALTH
one from students and executives to children and adults at all ages. To avoid fatigue and instead access unlimited energy from your fat-burning system, two things must occur. First, you need to develop and utilize the body’s aerobic system. Second, you need to provide that system with the proper fuel in the form of food. These items are discussed in the coming chapters. To maintain efficient fat-burning, you also must burn some sugar. Herein lies another example of balance. Both fat and sugar are almost always being burned for energy at all times. It’s a question of how much of each we use. Right now, you may be getting half of your energy from fat and half from sugar. When you improve your aerobic system and fat-burning capabilities, you may be able to obtain 70 percent of your energy from fat and 30 percent from sugar. But many people only get 10 percent of their energy from fat, forcing a full 90 percent to come from sugar. That’s a very inefficient and unhealthy way to get energy. This is the typical situation in people who are fatigued and attempt to obtain more energy from sugar because they can’t get much from fat. And when fat is not used for energy, it is stored in the body. This book explains how to reverse this situation and improve your fat-burning system. This mix of fuels used for energy can be easily measured in a person, and is something I have done during my years in practice and during other research. So when I say you can improve your fat-burning capability, it is because I have seen and recorded these changes in actual patients. These measurements are taken using a gas analyzer, which measures the amount of oxygen a person inhales and the amount of carbon dioxide exhaled. The ratio of carbon dioxide to oxygen gives the percentage of fat and sugar that is used for energy. This is referred to as the respiratory quotient, or RQ. I usually don’t recommend getting tested because for most people, when fat-burning is poor, there are plenty of signs and symptoms. These include the obvious — increased fat storage. Others include fatigue, blood sugar problems, hormone imbalance, poor circulation and even common physical injuries. Others are discussed throughout this book. In general, as fat-burning improves the body is able to correct many of its own problems. The bottom line — more fat-burning improves health, fitness and human performance.