Men and women who do not strength train lose about five to six pounds of muscle every decade of life. The loss of muscle tissue results in a 3 to 4 percent reduction in resting metabolic rate, and a 1 to 2 percent decrease in bone mineral density decade by decade.

Although people age at different rates on the outside, those who do not perform regular resistance exercise experience degenerative effects on the inside.

Men and women who do not strength train lose about five to six pounds of muscle every decade of life. This leads to a weak musculoskeletal system that adversely affects almost every other body system.

Additionally, the metabolic slowdown is largely responsible for the gain in fat weight experienced by most adults during the mid-life years. Fat typically accumulates at the rate of 15 to 20 pounds per decade, and is related to numerous medical conditions including diabetes, high blood pressure, heart disease, stroke and several types of cancer.

Time magazine just ran a cover story on the obesity epidemic and proclaimed that exercise is essentially ineffective for controlling body weight. For some very mild forms of aerobic exercise that may be true, but let’s examine the more popular approach of dieting. Since 50 percent of Americans are presently pursuing low-calorie diets, and since 70 percent of Americans are overweight, this is definitely not a preferable alternative.

Why hasn’t physical activity had a more pronounced impact on weight control? For one thing, recent research from the Centers for Disease Control and Prevention indicates that fewer than 5 percent of American adults perform 30 minutes of light exercise on a regular basis.

Another problem with popular physical activities is that they are not vigorous enough to require muscle remodeling and resting metabolic rate elevation. For example a 2-mile walk in 30 minutes burns about 200 calories, but 15 minutes after the walk metabolic rate is back to normal. While walking provides many physiological benefits, it is not very productive for weight reduction.

Contrast this with 30 minutes of circuit strength training. Let’s say you do 10 resistance exercises, 90 seconds on each machine and 90 seconds between machines. First, you will burn the same 200 calories as a 30-minute walk. Second, during the next 48 to 72 hours your resting metabolic rate may be 7 to 8 percent above normal. This is because brief bouts of resistance exercise cause some muscle microtrauma, which requires extra energy for tissue remodeling.

Consider these facts: Dieting typically reduces resting metabolic rate by 7 to 8 percent, aerobic activities generally do not change resting metabolic rate, and resistance exercise typically raises resting metabolic rate by 7 to 8 percent. Clearly, strength training is the best bet for attaining and maintaining a desirable body weight.

Wayne L. Westcott, Ph.D., is instructor of exercise science at Quincy (Mass.) College and author of 24 fitness books.

The Patriot Ledger