Many people believe that their body's most important leading indicator is the number on the scale. It can be all-consuming (especially when we know we're over-consuming). When the number's up, we feel our number's up too. When it's down, we are sooo up! It's one of the few areas in life where scaling down is downright desirable.

Our weight is critically important to our health but it's not a comprehensive measurement. Our body-fat percentage fills in the gaps. Most of us, however, don't know our body-fat percentage. And those of us who do, usually fail to monitor it regularly.

What is your optimal level of body fat? Well, your age, sex and heredity determine your parameters. Foremost, females are fatter than males. We are stingingly reminded when we decide to diet with our significant other, only to watch him lose it so effortlessly while prying a pound off our physiques is purely painful. It's enough to make us really lose it! We just may have to work harder to maintain a lean, healthy, curvaceous body.

A general guideline for acceptable body-fat percentages primarily fall within these limits:

For men up to age 30, 8 to 15 percent is acceptable; ages 30 to 50, 11 to 17 percent is acceptable; after age 50, 12 to 19 percent is good.

For women up to age 30, 13 to 21 percent is acceptable; ages 30 to 50, 15 to 23 percent is acceptable; and over 50, 16 to 25 percent is satisfactory.

To determine your body fat, have a trained professional such as a certified personal trainer measure your body fat with calipers. He will measure different areas of your body to determine your overall body-fat percentage.

A trainer can help you determine changes in your body fat once he knows your amount of lean mass. There are other methods to measure body fat, such as under-water weighing and through testing machines, however, calipers are generally more reliable.

You should measure your body fat every eight to 12 weeks to determine your changes, especially if you are on a diet and exercise regimen.

A skinny person can have too much body fat and a large person can be lean. The scale is not going to be a good predictor of health for everyone. It doesn't take into account your frame size, age or muscularity. Knowing your body fat and your weight can help you get a better handle on your health and a good grip on your girth.