Body composition analysis can tell you a how much fat and how much lean body mass you have, and help you find your best weight. The term body composition is mentioned by registered dietitians like me all the time—but what does body composition mean? Let me explain…
You’ve probably seen charts in your doctor’s office that provide a rough idea of what you should weigh. These charts take into account your weight, height, frame size and your gender. And then it provides an estimate of an appropriate weight for you. At best the charts can only classify you as underweight, at a proper weight, or overweight based on your frame size. What the charts don’t take into account is your body composition—that is, how much lean body mass and how much fat you have.
You can think of your total body weight (or body composition) as being made up of two parts: one part is your body fat, and the other part is your lean body mass. Your body fat can be further divided into two types: one type is termed essential fat, and the other is called storage fat.
Essential fat is made up of a very small amount of fat that is stored in organs—the heart, lungs, liver, spleen, kidneys and intestines. It’s also in muscle tissue, in tissues throughout the central nervous system and in the bone marrow. It’s termed essential fat because the body requires this fat in order to maintain normal bodily processes, such as temperature regulation, shock absorption and energy production. Women have more essential body fat than men do. Their bodys need to store energy in the form of fat to support childbearing and other hormone-related functions.
Storage fat, on the other hand, is the fat that serves to cushion the internal organs.Visceral fat, or abdominal fat, and the fat that lies just beneath the skin surface, (subcutaneous fat), serve to cushion the skeleton and conserve body heat. Excess accumulation of visceral fat is associated with various health concerns, which is one reason why it’s important to keep body fat within a healthy range.
Lean body mass is simply everything that’s not fat. This component includes your bones, organs, muscles, ligaments, tendons and fluids.
Lean mass and fat mass are made up of two entirely different types of cells and tissues, which is why muscle can’t turn into fat. If you stop exercising your muscles, it might seem as if that’s happened. Without resistance training to maintain your muscle mass, your muscles can become smaller. That can make the fat on the surface more apparent. But just as you can’t change a liver cell into a skin cell, you can’t change a muscle cell into a fat cell.
Body composition analysis provides useful information that can be used to distinguish between someone who is ‘thin and someone who is ‘lean,’ as well as someone who is ‘overfat’ and someone who is ‘overweight.’
For instance, someone who weighs less than a height and weight table suggests would be classified as ‘thin.’ But since body composition isn’t taken into account by the height and weight table, that person could actually be carrying excess body fat. In that case they’d actually be ‘overfat.’
On the other hand, someone who weighs more than a height and weight table suggests would be classified as ‘overweight.’ But, again, since body composition isn’t taken into account, that person could actually have a low body fat percentage (like an athlete who has a lot of muscle). In that case they’d actually be ‘lean.’
This is important because it’s excess body fat, not simply excess weight, that has an impact on an individual’s overall health and well-being. Healthy body fat levels are around 15% for men and 22% for women, but these values will vary depending on your age. While it’s true that having excess body fat can put your health at risk, you do need to carry some body fat, because it performs some important body functions.
A proper diet and exercise program can help individuals achieve and maintain a healthy body weight and shape. A proper exercise program can help to build and maintain muscle mass and, therefore, increase the body’s lean mass. At the same time, a weight management program can also help to reduce overall body fat.
Keep in mind that you can’t target your fat loss or spot reduce. Yes, if you do a lot of exercise that targets your abs or your legs, you’ll tone the muscles underneath and that will make you look slimmer. But when you lose body fat, you lose it more or less uniformly. If you start out heavy and curvy and then lose weight, you’ll probably keep your curves. And if you’re built without much of a waistline, you can’t really create one no matter how many sit-ups you do. When you lose body fat, your basic shape will be more or less the same—only smaller.
Susan is the Sr. Director of Worldwide Nutrition Education and Training at Herbalife, where she is responsible for the development of nutrition education and training materials, and is one of the primary authors of the Herbalife-sponsored blog, www.discovergoodnutrition.com. She is a Registered Dietitian and holds two Board Certifications from the Academy of Nutrition and Dietetics as a Certified Specialist in Sports Dietetics, and a Certified Specialist in Obesity and Weight Management. Susan is also a Fellow of the Academy of Nutrition and Dietetics.
Susan graduated with distinction in biology from the University of Colorado, and received her master’s degree in Food Science and Nutrition from Colorado State University. She then completed her dietetic internship at the University of Kansas. Susan has taught extensively and developed educational programs targeted to individuals, groups and industry in her areas of expertise, including health promotion, weight management and sports nutrition.
Prior to her role at Herbalife, she was the assistant director of the UCLA Center for Human Nutrition, and has held appointments as adjunct professor in nutrition at Pepperdine University and as lecturer in nutrition in the Department of Food Science and Nutrition at Cal Poly San Luis Obispo.
Susan was a consultant to the (then) Los Angeles Raiders for six seasons, and was a contributing columnist for the Los Angeles Times Health Section for two years. She is a co-author of 23 research papers, 14 book chapters, and was a co-author of two books for the public: “What Color is Your Diet?” and “The L.A. Shape Diet” by Dr. David Heber, published by Harper Collins in 2001 and 2004, respectively.