We live in a generation that is generally characterized as underfit and overfat. Population studies show that 90 percent of Americans do too little exercise to receive any measurable benefit from it. In spite of our national emphasis on fitness and sports, it seems that most people are observers rather than participants.
Research reveals that one out of three Americans is obese, making overfatness nothing short of a national epidemic. In spite of the fact that over $30 billion is spent annually on diet programs, the incidence of obesity has increased by 25 percent in the last 15 years. What’s wrong with this picture?
First, exercise works, but too few people are doing it. Second, everyone is dieting, but diets don’t work. Well, not everyone is dieting, but research reveals that one out of two American women and one out of four American men are presently on a calorie-restricted diet.
Why don’t diets work? If you cut down the number of calories you consume, you should lose weight, right? Yes, and you definitely do lose weight on calorie-restricted diets. But your weight loss is almost always short-lived. Studies on calorie restriction and weight loss show that 95 percent of all dieters regain all of the weight they lost within the following year. Whatever happened to willpower?
Actually, willpower has very little to do with whether or not the lost weight is regained. It’s more a matter of physiology than psychology. About 25 percent of the weight loss is muscle tissue, and less muscle results in a lower metabolic rate. In other words, you have less vital tissue to service, so you burn fewer calories daily. Meanwhile, your body adjusts to the low-calorie diet by slowing down your metabolism even further.
You may not notice the detrimental effects of a slow metabolism while dieting, but as soon as your calorie intake is increased, which must happen for you to survive, you will be surprised at how quickly that weight you lost comes back.
So why do people work so hard on something that works so poorly? Primarily because diets do produce satisfying short-term results. With exercise, short-term changes in total bodyweight are relatively small because exercisers typically add lean weight and lose fat weight at the same time.
For example, in a classic study conducted at Tufts University, 12 senior subjects were placed on a basic program of strength exercise. They performed about 30 minutes of strength training three days per week for 12 weeks. As a result they added 3 pounds of lean (muscle) weight and lost 4 pounds of fat weight. Although their bodyweight changed by one 1 pound, they actually made a 7-pound improvement in body composition.
What’s more, to keep the participants’ bodyweight relatively constant, the researchers had to increase their caloric intake throughout the study period. During the last few weeks of the study, the exercisers were eating 15 percent more calories every day to maintain their bodyweight. Unlike dieting, the strength exercise resulted in more muscle and the need for more calories as the subjects lost fat. Of course, if the subjects had not increased their calorie consumption throughout the study, they would have lost even more fat weight.
In our own larger study, 383 men performed 25 minutes of strength exercise and 25 minutes of endurance exercise two or three days a week for eight weeks. This combination exercise program produced a 6.4-pound fat loss and a 3.7-pound muscle gain, for a 10-pound change in body composition.
These improvements resulted from two months of basic exercise, so these men must have been in pretty good shape to start with, right? Actually only a small percentage of the participants began the program with a desirable body composition. The rest started with varying levels of overfatness.
As presented in Table 1, the men were divided into five categories based on their initial body fat assessment: (1) less than 15 percent fat; (2) 15-19 percent fat; (3) 20-24 percent fat; (4) 25-29 percent fat; and (5) 30 percent fat or more. The participants’ beginning bodyweights averaged about 20 pounds heavier in successive categories, ranging from 169.9 pounds to 247.9 pounds, and body composition improvements were greater in successive categories, ranging from a 1.1 to a 6.3 decrease in percent fat.
As illustrated in Table 2, the men who began the program with higher percent-fat scores lost more fat weight and gained more lean weight. Since this finding was consistent category by category, it seems that excess fat did not limit the effects of the exercise program. In fact, the results of this study indicate that people with more body fat may experience more improvement from a basic exercise program than those with less body fat.
A parallel study of 749 women divided into five initial percent-fat categories produced similar results. That is, the women who began the program with more fat generally achieved better body composition improvements.
So does exercise work for people who are overfat? Yes, and it works much better than dieting. Unlike dieting, which reduces lean weight, exercise programs that include strength training add lean (muscle) weight, which increases resting metabolism and burns calories all day long for better weight control. Unlike dieting, which cannot be continued very long, exercise can, and should become a permanent part of your lifestyle. Unlike dieting, which requires attention all day, exercise requires only an hour of your time two or three days a week. And unlike dieting, which subtracts something good from your life (food), exercise adds something good to your life (physical activity).
While dieting alone is not recommended, a sensible eating plan combined with a basic exercise program is probably the best way to attain and maintain a desirable body weight. The American Heart Association guidelines of a diet composed of 10 percent fat, 20 percent protein and 60 percent carbohydrate provides heart-smart nutrition with limited fat calories. This sustainable nutrition program, combined with a regular strength and endurance exercise, can contribute to better health as well as improved body composition.
The exercise protocols in our studies are consistent with the recommendations of the American College of Sports Medicine. The endurance training program consists of about 25 minutes of continuous treadmill walking or stationary cycling at approximately 75 percent of maximum predicted heart rate. The strength-training program consists of eight to 12 repetitions of 12 exercises for all major muscle groups. Every repetition is performed at a slow movement speed through a full movement range.
The participants perform the exercises (Leg Extension, Leg Curl, Leg Press, Double Chest, Super Pullover, Lateral Raise, Biceps Curl, Triceps Extension, Low Back, Abdominal, Neck) in the general order of larger to smaller muscle groups. Exercise intensity is increased gradually by means of a double-progressive training system in which the participant alternately adds repetition and resistance. For example, if you do eight repetitions with 50 pounds, continue to use this resistance until you can perform 12 repetitions. Then, increase the weightload by 5 percent to 52.5 pounds. When 12 repetitions can be performed with this resistance, increase the weightload to 55 pounds.
To ensure productive training, each repetition is performed in six seconds – two seconds for the lifting and four seconds for the lowering movement. This technique reduces the role of momentum and makes the important negative muscle contraction more demanding. The goal is to make every repetition count, so that one properly performed set of exercise provides sufficient stimulus for muscle development.
Our experience indicates that this basic program of strength and endurance exercise is a safe and effective means of improving physical fitness and body composition in men and women of all ages. It is also a time-efficient approach to training, requiring only 50 minutes of exercise two or three times per week. Perhaps more significant in our sedentary society, it is a program that produces particularly good results for overweight people with various percentages of body fat. Getting back to basic exercise may be the key for adults for those who want to attain, and maintain a desirable bodyweight and body composition.
Bodyweight and body composition data for male exercisers, categorized by initial percent body fat (N = 383).
|Percent Fat Intial Reading||Body Wt. Pre (lb.)||Body Wt. Post (lb.)||Body Wt. Change (lb.)||Percent Fat Pre (%)||Percent Fat Post (%)||Percent Fat Change (%)||Fat Wt. Pre (lb.)||Fat Wt. Post (lb.)||Fat Wt. Change (lb.)||Lean Wt. Pre (lb.)||Lean Wt. Post (lb.)||Lean Wt. Change (lb.)|
|Under 15% (n=51)||169.9||168.8||-0.8||12.8||11.7||-1.1*||21.9||19.9||-2.0*||147.7||148.9||+1.2|
|30% Plus (n=31)||247.9||240.9||-7.0*||36.0||29.7||-6.3*||91.2||72.5||-18.7*||156.7||168.4||+11.7*|