Wayne L. Westcott: Resistance exercise, dieting can slow aging
For the past 25 years, I have been a strong advocate of regular resistance exercise for reducing body weight and improving body composition.
Body composition is typically expressed as body-fat percent, with less than 25 percent fat considered desirable for women and less than 15 percent fat considered desirable for men.
As an example, a 100-pound woman who is 25 percent fat would have 25 pounds of fat weight and 75 pound of lean weight (muscle, bone, blood, skin, organs, etc.).
The percentage of fat weight typically increases with age because people who do not perform strength training lose 5 pounds of muscle per decade. This degenerative process is directly related to reduced resting metabolic rate, which almost inevitably leads to fat gain.
Strength training is a highly effective means for avoiding muscle loss. It also increases resting metabolic rate by more than 100 calories per day, which contributes to fat loss. I would like to share the results of two recent studies that support the efficacy of resistance exercise for weight loss and body composition improvement.
The first study was conducted at a sports club in Massachusetts by my exercise-science student Rachel Cacta.
Participants were 35 men and women who performed strength training two or three days a week for 10 weeks. Each week, they did one or two days of standard resistance exercise (10 weight machines) and one day of functional strength training (exercise combinations with resistance equipment).
Rachel assessed her clients’ bodyweight and combined inches for several body parts (thighs, hips, waist, chest, upper arms) before and after the strength training program. The top performers in the four age groups achieved the following results:
Ages 25 – 30 years: Loss of 7 pounds and 12.5 inches
Ages 31 – 45 years: Loss of 11 pounds and 12 inches
Ages 46 – 59 years: Loss of 17 pounds and 12.5 inches
Ages 60 years and older: Loss of 7 pounds and 11 inches
Although Rachel attributes most of the program’s success to strength training, she also encouraged participants to drink lots of water and to eliminate processed foods as much as possible. The combination of resistance exercise, more water and better nutrition prove to be an effective formula for weight loss and size loss for participants.
The second study, conducted in our Quincy College Exercise Research Center in Massachusetts, included 85 men and women who performed strength training and endurance exercise two or three days a week for 16 weeks.
The strength program required one set of 12 Nautilus machine exercises, and the endurance program involved 20 minutes of interval training on recumbent cycles. Participants were offered three nutrition options: the USDA Food Pyramid, the reduced-sodium DASH diet plan and the Protein Power diet plan that places a higher emphasis on protein-rich foods.
Our before-and-after training assessments included four categories related to weight loss and body composition factors. Category one was reduction in bodyweight; category two was fat loss; category three was muscle gain; and category four was reduction of inches from hips and waist.
The average improvements from the top five performers in each category were quite impressive:
Average decrease in body weight: Loss of 9.7 pounds
Average decrease in fat weight: Loss of 7.9 pounds
Average increase in muscle weight: Gain of 9.8 pounds
Average decrease girth in hips and waist: Loss of 5.1 inches
Almost all program participants concurrently increased muscle and decreased fat, which reverses the typical aging phenomena of muscle loss and fat gain. This is important from several perspectives, including improved body composition, increased physical fitness, enhanced physical appearance and reduced health risks (e.g., obesity, sarcopenia, osteopenia, diabetes, heart disease, back pain, etc.).
It should also be observed that weight loss is not necessarily a good indicator of body composition change. For example, a participant who loses 10 pounds of fat and builds 5 pounds of muscle records only a 5-pound weight reduction when, in fact, this represents a 15-pound improvement in body composition (and physical appearance).
While it is possible to reduce body weight by dieting alone, at least 25 percent of the weight lost will be muscle tissue, which leads to a lower resting metabolism and, essentially, ensures that the weight will be regained.
This is the main reason that 95 percent of successful dieters regain all the weight they lost within one year. It is, therefore, highly recommended to include resistance exercise in your weight reduction regimen.
Instead of experiencing muscle loss and metabolic slowdown, you should enjoy they many benefits of muscle remodeling and metabolic recharging, which is by far the best means for attaining and maintaining desirable body weight and body composition.
Wayne L. Westcott, Ph.D., teaches exercise science at Quincy College in Massachusetts and consults for the South Shore YMCA. He has authored 24 books on physical fitness and strength training.