Muscle is a tissue, but it's also metabolically active - meaning you burn about 14 calories each day for every pound of muscle on your body. Meanwhile, fat burns only about 3-5 calories a day and that's a big difference. Basically, the more muscle you build, the more calories you'll burn, the more fat you'll lose and the more likely it will stay off for the long term.

Muscle isn't just a calorie-burner either; it's also a metabolism booster, meaning you can keep weight off. For example, when you diet without exercising, you lose both fat and muscle, making your body less capable of keeping that weight off. However, when you build muscle and diet, you're creating a metabolic foundation for keeping your body burning calories even when you're resting.

Muscle also helps promote our overall bone health. Our bones are constantly changing - growing, depleting and restructuring with our bodies. As women age, we lose bone mass, but this depletion can be curtailed and prevented with a regular weight resistance program like muscle development.

Finally, muscle mass is one of your greatest tools in the fight against aging. Nothing will make your skin smoother, or your body firmer and tighter than solid muscle. No cream or surgery can accomplish what a few months of solid weight resistance training when it comes to halting the aging process.

So, if you're interested in building muscle mass or beginning a weight training program to improve both your health and your body, consult with your local fitness center or check out books and DVDs at your local library or book store. Always consult a health professional before beginning any major exercise program.