It's an interesting phenomenon. Ten times as many Americans are attempting to lose weight by dieting, which doesn't work, than by exercising, which does work.
One of every two American adults is following a reduced calorie diet plan, but according to a recent review of dieting studies, almost all dieters regained all of the weight lost during their restricted calorie period. Meanwhile, a 2008 study of physical activity in the United States found that less than 5 percent of adults perform even 30 minutes of moderate activity on a regular basis, defined as five days a week.
Perhaps the reason more people don't pursue an exercise approach is because the weight loss, although more permanent, comes more slowly than that attained by dieting. However, two 20-minute strength training sessions per week could be a large part of the solution.
The reason for this is the reduction in muscle tissue and metabolic rate that accompanies the aging process. As we age, our muscle mass decreases by 4-6 pounds per decade and our metabolic rate decreases by 2-3 percent per decade. While this may seem a minor factor in weight gain, a 2-3 percent per decade metabolic rate reduction results in a 15-20 pound fat accumulation, other things being equal. That is approximately the amount of fat middle-age adults gain on a decade by decade basis.
The good news is that it is relatively simple to reverse this process of muscle loss and metabolic slowdown. Several studies have demonstrated that a brief strength training program can increase both muscle tissue and resting metabolism.
One reason for the increased metabolic rate is that more muscle requires more energy for tissue maintenance.
Assuming average adults have a resting metabolism of 1,500 calories per day, an 8 percent increase would represent an extra 120 calories used every day for tissue maintenance. Other things equal, that's about 3,600 additional calories used at rest on a monthly basis, which is equivalent to a one-pound fat loss. These figures are consistent with the results of our large-scale study with 1,644 men and women who performed 10 weeks of standard strength and endurance exercise (20 minutes of each per workout). The participants added muscle at a rate of almost 1.5 pounds per month, and lost fat at a rate of almost two pounds per month. Approximately one pound per month of fat loss was due to the calories burned during exercise, and approximately one pound per month could be attributed to increased resting energy expenditure.
Based on these studies, it would make sense to include basic strength exercise in weight loss programs. Although the beneficial increase in muscle weight may result in less overall weight reduction, it should increase the rate of fat loss, enhance body composition improvement, and elevate resting energy expenditure on a permanent basis.
Wayne L. Westcott, Ph.D., is senior fitness executive at the South Shore YMCA in Quincy, and author of 22 books.
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