Low Calorie Dieting - Beginner's Guide

Your metabolism is the sum total of all the chemical reactions and changes that are constantly going on in your body. These processes include fat production, protein breakdown, toxin removal, and the general growth, replacement, and repair of body cells that’s necessary for overall good health. Concerning weight control, however, the focus is on energy metabolism, the process by which your body breaks down nutrients from food and converts them into energy.

Energy metabolism begins as soon as your body digests food and breaks it down into its respective nutrients. Your body can use three different nutrients for energy: carbohydrates, fats, and protein. (Alcohol also supplies energy, but because it contains no nutrients and can potentially damage your health, it’s not considered a good source.) Together, carbohydrates, fats, and protein are known as macronutrients. (Check out Chapter 3 for more about these and other nutrients.) Your body metabolizes each of these macronutrients differently from the rest.

In general, your metabolism works the same way as everyone else’s, but the rate at which you metabolize nutrients is unique to you. How your body uses the food you eat to create energy, and how the different foods you eat affect your weight and your overall health, is a very individual matter. If you have a fast metabolic rate, you’re able to burn calories more efficiently than someone with a slower metabolic rate. Many factors — age, gender, hormones, body composition, body temperature, and your current state of health — affect energy metabolism and help determine how effectively your body uses food to generate energy.