Most Americans wish that they weighed less than they do. Two-thirds of us are overweight. At the same time, there are literally hundreds of weight loss programs—each one promising that it will help you finally lose those extra pounds. Some of them work—and you are able to lose weight. But most people gain back the weight they lost—and more—when they begin to eat normally again. Why do these programs not fulfill your dream of reaching your desired weight—and staying there?

Bodies, They Are A’changin’

To find out, let’s discuss what happens to your body as you grow older. Adults who do not perform regular strength exercise lose about one-half pound of muscle each year after they reach maturity. This means ten pounds of muscle are lost during their 30s and 40s. And the rate of muscle loss doubles in people over 50 years of age. Many women have lost half the muscle they had at 30 by the time they are 70.

In addition, most adults gain ten pounds of weight—fat—each decade If you lose one-half pound of muscle each year, by the time you reach 40, you have lost five pounds of muscle. Each pound of muscle in your body burns about 50 calories per day; therefore your body requires 250 fewer calories each day to maintain your weight.

When you reach 50, you need 500 calories less each day than when you were in your twenties. Most people believe their metabolism slows down; actually it seems that way because they have less muscle to burn calories.

Where That Belly Comes From

This gradual decrease in muscle and basal metabolism rate is also related to the increase in body fat that most people experience as they get older if they do not strength train. With the decrease in muscle, calories previously necessary to perform the activities of daily living now end up stored as fat. They then diet to lose weight, which further reduces their muscle mass because 30 percent of the weight lost through dieting is muscle tissue.

Losing muscle leads to a lower metabolic rate because fat needs almost no calories to sustain its self, thus causing even more calories to be stored as fat which makes it more difficult to perform physical activities. When you diet to lose weight, for every ten pounds of weight you lose, you lose three pounds of muscle. You have exacerbated the loss of muscle that’s already been happening to your body.

How Weight Loss Lowers Your Metabolism

Let’s say you lose 20 pounds by dieting without strength training. Thirty percent of those 20 pounds you’ve lost were muscle—that’s six pounds of muscle that is gone. If you estimate that each pound of muscle uses 50 calories each day to sustain itself, 50 calories times six pounds equals 300 calories each day that your body does not need now to sustain itself. If you were eating 1,500 calories a day to lose weight, you now have to lower that to 1,200 calories. This is why you reach a plateau and are no longer dropping pounds. Get the picture?

Bottom line: if you gain ten pounds of muscle, you’ll increase your metabolism and your body’s caloric needs up to 500 calories per day. Wow! That means an extra piece of cake won’t add on another pound. Plus—you’ll find that strength training gives you more energy and a sense of well-being. It helps firm up your body as you lose pounds—so you’ll look better, too.

So get out the dumbbells or go to the gym and get started pumping iron. You’ll be glad you did.

Phyllis Rogers is certified as a Specialist in Fitness for Over Adults and is the author of“Over 40 & Gettin’ Stronger.” For information on her book go to: www.StrongOver40.com.

Incidentally, the muscle loss effects are even worse with high protein, low carbohydrate, fasting, or extremely low calorie intakes. A low carbohydrate intake jeopardizes the brain’s glucose supply, which signals an even greater amount of muscle and fat breakdown than usual. Aquatic Exercise Association Manual pg 249