Don't you just want to pick up the bathroom scale and heave it out the window sometimes? Here you are, trying your best to exercise regularly and, darn, if that needle doesn't refuse to bobble downward. You feel more energetic. Your clothes fit more loosely. Your doctor even says your blood pressure and cholesterol are down.

Why doesn't your body weight go down? You're about ready to give up on the healthy resolutions, retreat to the couch with a jumbo package of fudge-dipped Double Stuf Oreos and watch reruns of "Bonanza" and "The Brady Bunch" for the rest of your years.

Forget what the scale's needle tells you. You are already healthier because a combination of exercise and good nutrition lowers your percentage of body fat. Carrying less fat, not less weight, is the key to good health and the bottom line to your bottom line, fitness and health experts now agree.

"Extra fat really has no use," said Los Angeles-based exercise physiologist and personal trainer Douglas Brooks. 'It's just an extra weight the body has to transport. It just makes us a less-efficient machine.'

Excess fat also invites a list of deadly diseases including heart attack, diabetes and stroke, as well as risks that can add up to cardiovascular disease, such as elevated blood pressure, cholesterol and insulin levels.

Your risk shoots even higher if you have what some call "Michelin's Disease," or a spare tire of fat around the middle. Men typically gain fat there, while women normally gain fat lower around their hips and thighs. Fat apparently finds its way into the blood stream easier from the midsection.

A certain amount of fat is essential to protect organs and to maintain certain body functions. The essential stuff is OK. An average healthy woman carries four times as much essential fat--the stuff buried deep around reproductive organs, in breasts and laced through muscle--as does a man. Add a few pounds of fat stored underneath the skin and total percent of body fat for a woman in good health reaches 22-25%. A fit man in good health is 15-18% fat.

"You are going to jiggle," said Covert Bailey, international lecturer on weight management and author of several books including "Fit or Fat" and "Fit or Fat Target Diet."

Figuring out whether you've got more than your share of fat is the first step to finding out how your health ranks. Forget the scale because it counts everything, including bones and organs, so that number tells you very little, Brooks said.