We live in a culture that has become increasingly more obsessed with body image and weight. Dangerously thin bodies are celebrated and coveted, perpetuating the unrealistic goal of obtaining an ideal body--one devoid of any trace of fat. The pencil-thin models we see when we turn on our televisions or flip through our favorite magazines have a major influence on how we feel about our own bodies. We often compare ourselves to these slender public figures, and all too often we end up feeling like we don't measure up.

We all know that many celebrities and models have body fat percentages that are below what is termed "normal" or even "healthy." But with all of this talk about body size, body composition, and weight, we often lose focus on what is important: our health. A thin body does not necessarily equate to a healthy body. In fact, our bodies require a certain amount of fat in order to function properly.

Why Your Body Needs Fat

Your body requires a minimum percentage of body fat normal functioning, and this amount varies quite significantly for males and females. The human body needs a certain level of fat for several reasons:

• Fat provides insulation for the body.
• It is required to metabolize the fat-soluble vitamins A, D, E, and K
• It is essential to the formation of cell membranes and hormones.
• It is used in many chemical reactions that take place in the body.

Women naturally need more body fat related to child-bearing. Normal bodily functions could be disrupted if your body fat percentage falls below a certain level. For men, the minimum amount of body fat percentage for survival is 5%; for women, it's 8%. However, there are ranges established for optimal health--for men this range is 10-25%, and for women it's 18-30%.

The Dangers of Being Too Skinny

Being too thin can be just as dangerous as being overweight or obese. For example, women need to have at least 13-17% body fat in order to menstruate, a normal body process. If a woman loses too much weight--to the point that her natural menstrual cycle stops completely--this is her body's way of telling her that she has become too thin.

In addition to causing temporary infertility, having too little body fat can negatively affect the health of your bones. Your bones require a certain amount of estrogen, a hormone produced by the ovaries, adrenal glands, and fat tissues.

How to Determine Your Body Composition

There are several ways to determine body composition. The "gold standard" is hydrostatic weighing (underwater weighing). This method has been proven to be the most accurate at finding body fat percentage, but it's expensive and difficult.

Another reliable method is called bioelectrical impedance analysis. This method has become popular because it is reliable, fast, easily-administered, and pain-free.

Finally, there is the skinfold method, which is quick, cheap, and easily-administered. However, the drawback of the skinfold method is that its accuracy depends on the skill of the person administering the test as well as the quality of the calipers used. If you'd like to know your body fat percentage, ask your local gym if they provide any of these body composition tests.