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Why is body composition analysis important? |
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Misleading Height/Weight Charts: The need for body composition analysis resulted from the apparent inappropriateness of height/weight tables in assessing health status for athletes. Referring to standardized height/weight charts for "ideal" bodyweight is often misleading. For example, a football player who is heavily muscled, yet very lean will be categorized as "over fat," while individuals with very little muscle mass but elevated proportions of fat are often classified as "normal" or "under fat."
Basically, body composition is the relative amount of fat and fat-free body tissues in the body, typically expressed in terms of percent body fat. Fat-free body mass (FFB) consists of fat-free muscle, bone, and organs. Body composition analysis appears to be a better indicator of health status regardless of an individual's weight.
There are several field methods currently being used to determine the ration of fat to FFB in the body. The most common, practical, and least expensive method is the "Skin fold Assessment," which is often used to screen a large number of individuals in a time-efficient manner. However, technology has progressed to include the Futrex Near Infrared Light Method and the Bioelectric Impedance Technique. |
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What is the recommended percent body fat range for good health? |
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At NutritionRx™, the recommended range for body fat for "optimal health" is 12-20% for adult men and 18-25% for adult women (table1). These numbers are subject to individual variation.
Body Fat Content:
Essential Fat: Men (2-5%) Women (5-10%)
Optimal Health: Men (12-20%) Women (18-25%)
At Risk: Men (Greater than 25%) Women (Greater than 30%) |
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What percentage of body fat is considered too high? |
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Americans typically gain about a pound a year after age of 25. In addition, our sedentary lifestyle contributes to the yearly loss of about one-half pound of lean body weight (primary muscle) and gains one-half pound of fat. Thus, the average adult acquires about 30 pounds of extra fat over a twenty-year period. "At Risk" is considered to be 25% and 33% body fat or more for men and women respectively. This level of body fat puts an individual at a higher risk for hypertension, coronary artery disease, diabetes, orthopedic injury, and other chronic diseases. |
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What percentage of body fat is considered too low? |
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A certain amount of fat is necessary for normal physiologic functioning. For men, this level of essential fat appears to be 2-5% of total body weight, whereas women have approximately 5-10% essential fat. For women, minimal fat levels have a much greater individual variation.
There may be a critical level of body fat necessary for the normal production and effectiveness of estrogen. There appears to be an increased incidence of amenorrhea (absence of menstruation following menarche for a period of six months or three regular cycles) among women athletes. However, many women under 18% body fat have normal menstrual cycles, and others may become amenorrheic at "normal" percents of body fat. There appears to be a significant correlation between a deficient estrogen level and osteoporosis. This may put the amenorrheic athlete with low estrogen levels potentially at risk for decreased bone density and a greater likelihood of stress fractures doing physical training or osteoporosis fractures than later in life. There are a variety of factors that have been proposed as potential mechanisms of athletic amenorrhea than body composition, including psychological stress, training regimen, nutrition, and heredity. |
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What is the most efficient way to reduce body fat and then keep it off? |
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The benefits of Aerobic ExerciseL: Research indicates the optimal approach to weight loss combines a mild caloric restriction with regular aerobic exercise. The tremendous advantage to aerobic exercise of a moderate nature is its superb efficiency. Sustained aerobic exercise can elicit the greatest caloric expenditure when compared to any other form of exercise.
The American College of Sports Medicine recommends an energy expenditure of 300-500 calories per exercise session and 1000-2000 calories per week. Accompanied with this of course is a mild calorie restriction of not less than 122 calories per day. Typically, one must exercise four to six times per week, for thirty to sixty minutes at approximately 70-85% of one's predicted maximum heart rate (PMHR) to burn enough calories to be considered an effective weight loss regime. A realistic and safe rate of weight loss is approximately one to two pounds per week. It has been demonstrated that this amount of aerobic exercise may:
- Elevate the basal metabolic rate (resting metabolism) and sustain this elevation up to four hours post-exercise.
- Help maintain an individual's FFB which in turn helps sustain the basal metabolic rate during the aging process.
- Help retard the resistant phase (plateau) of weight loss.
- Increase an individual's fat utilization in the more aerobically training individual, at rest and during exercise.
- Help regulate the appestat in the hypothalamus of the brain so that the appetite is able to respond more appropriately to the body's physiological needs. This "appetite center" may function more effectively when one exercises regularly, thereby facilitating the maintenance of a desirable weight.
- Stimulate a more rapid passage of food through the digestive system and thus discourage surplus food storage. When a meal directly follows exercise, the metabolic rate exceeds the sum of both alone.
Permanent Success Through a Moderate Diet
By drastically restricting one's caloric intake on a rapid weight loss diet, fat loss is typically accompanied by loss of lean weight, or muscle. This is especially true if exercise is not incorporated along with the diet. Since muscle is metabolically active tissue, loss of lean weight would result in a reduced basal metabolic rate (BMR). This loss of lean weight is often regained as fat. Therefore as the number of weight loss/regain cycles increases, greater caloric restriction is required to obtain similar weight losses. It becomes more and more difficult to lose fat, let alone keep it off.
Gradual, sustained weight loss through a combination of aerobic exercise and a moderate diet appears to have the greatest permanent success. Although, it usually takes a considerable length of time for most people to accumulate the excess fat they desire to lose, many are unrealistic concerning the length of time they should expect to spend in a weight loss regime. In other words, no one should expect to lose in several weeks what took years to gain. |
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What types of exercises are best to tone abdominals, hips, and thighs? |
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Spot reduction doesn't work! Aerobic exercise is still the best type of exercise to reduce fat. It has been well established that one cannot "spot reduce" fat by exercises that work specific areas (e.g. abdominal crunches will not reduce the fat covering these muscles). Unfortunately, we are limited to our own personal genetic pattern of laying down (or removing) fat. The "last-on-first-off" concept still tends to hold true. Fat is lost in the reverse order it is put on, often leaving those problem areas last to go no matter what type of exercise you do! Isolating one muscle group at a time burns very few calories compared to aerobic activity where a number of large muscle groups are contracting continuously for a sustained period of time.
Muscle Endurance (toning) Exercises have LIMITED Benefit in Shaping Muscle. Muscular endurance is the ability of a muscle group to exert force or maintain a degree of force over a long period of time. This component of fitness is best developed through programs of high repetition (anything over 12 repetitions) and low resistance. Typically muscular endurance exercise includes calisthenics on land or in the water, lightweight training exercises, and aerobic exercise. Body composition changes have certainly been observed with aerobic exercise, but not with isolated muscle endurance exercises such as calisthenics. Although some subtle shape change may occur in the muscles worked initially in the program, the benefits are limited. After building a foundation of muscle endurance, strength training is recommended for further muscle shape change, contour, and definition. |
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How can I tone up without bulking up? |
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Strength training exercises can change body composition, reduce fat layers, and enhance muscle shape and contour. A common misconception among women is that strength training will cause them to "bulk up," becoming larger and heavier. Strength training studies have "repeatedly demonstrated favorable alterations in body composition in women as a reduction in fat weight, an increase in lean weight, and either no change or only a slight increase in total body weight." Increases in muscle mass with subsequent reductions in fat would be beneficial for a number of reasons:
- Increases lean body mass - enhances muscle shape and contour
- Decreases percent body fat - less fat covering muscle, enhances muscle definition
- Increases BMR (basal metabolic rate)
- Increases muscle strength and power - enhances sport performance
- Enhances posture
- Decreases risk of injury
Muscle is metabolically active tissue. Conversely fat has little metabolic activity. Having more muscle (and a height BMR) would appear to aid in fat loss as well as weight control. This may also help the yo-yo dieter who has significantly lowered BMR. This should not take place of aerobic activity in a fat loss program, but may be considered as a supplement at some point in the program.
Muscular strength is the force (torque) a muscle or muscle group is able to exert against a resistance in one maximal repetition (1 RM). Strength is developed using progressive resistance exercises, which overload (>66% of 1RM) the muscle groups. Just as with aerobic exercise, where the heart rate must be elevated to a certain threshold level to receive cardiovascular benefits, a muscle must be overloaded to a certain degree in order to change its shape. This would be a weight one could lift no more than approximately eight to ten repetitions. Strength gains can occur with a single set, however, multiple sets (three to six) have been shown to produce significantly greater strength gain. In general, muscle strength gains can be most effective when attained by using free weights or weight training machines. |
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What is the ideal home exercise program to change body composition? |
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An ideal program to change body composition would be a combination of aerobic exercise (first priority) to reduce fat, and a weight-training program to develop and shape muscles. Begin with Part I and add Part II when ready. (Figure1) When Part II is added to the home exercise program two to three days per week, it is recommended to combine 20-45 minutes of aerobic exercise followed by 20-30 minutes of strength training. (Figure 2) On the fourth (or more) exercise day, a longer aerobic session may be done.
Part I: Aerobic Exercise Guideline (fat loss):
Type: Walk, jog, cycle, swim, aerobics classes, aerobic equipment (treadmill, bike, stair climbing, rowing) etc.
Frequency: 4-6 days per week
Duration: 30-60 minutes
Intensity: 70-85% of PMHR
Part II: Strength Training Guidelines:
Type: Free weights or weight training machines
Frequency: 2-3 days per week (1-3 days between sessions)
Duration: 20-60 minutes
Intensity: 2-6 sets or 8-10 repetitions per muscle group
Warm up (5 minutes):
Aerobic Conditioning (20 to 45+ minutes)
Cool Down (3-5 minutes)
Strength Training (20-30 minutes)
Stretch (5+ minutes) |
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I keep hearing how important it is to increase my fiber intake. What is fiber and how much do I actually need in order to be healthy? |
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Fiber is essentially the component of plants that is resistant to digestion. Unlike other nutrients, it simply passes through the stomach and intestinal tract without being broken down by digestive enzymes. What also makes fiber important is its special ability to pick up other molecules in the course of its journey through the digestive system. One such molecule is water. Since heavier stools are generally better moved stools, fiber helps avert constipation by adding "weight" in the form of water to the system. Fiber also has a penchant for picking up substances like hormones, vitamins, and bile acids which accounts for its apparent role in preventing cancers of the colon and breast, reducing cholesterol, and minimizing the complications of diabetes. In a fruit, vegetable or grain the amount of fiber depends on the age and type of the plant from which it is derived. Insoluble fiber includes wheat bran, the skins of fruits and vegetables, the whole of strawberries and raspberries, buts and beans. Soluble fiber, best known for its role in reducing cholesterol through the form of oat bran, is also found in barley and lima beans.
There is no agreement on exactly how much fiber we need. The American Dietetic Association recommends from 25-35 grams of fiber per day. Since most sources have between one and three grams per serving you can achieve this amount by eating five servings of fruits and vegetables a day, along with a cup or two of whole grain cereal most days and two slices of whole grain bread daily. A word of warning: Increase your fiber intake gradually by adding a serving or two a day. Because fiber absorbs water, remember to drink at least six 8 ounce glasses a day. |
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Ever since I can remember, MSG has been a controversial ingredient. I remember when my parents' fear of Chinese Restaurant Syndrome profoundly reduced how much of the cuisine we were allowed to eat. Now that I have a family I would like to know the facts. Is it hazardous to our health to consume foods containing MSG? |
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MSG, or monosodium glutamate, is as omnipresent in our food supply as salt and sugar. Gone are the days when Chinese food was the primary source of this flavor enhancer. Often listed on the package label as "natural flavoring", you might find it in spaghetti sauces, salad dressings, frozen entrees or even puddings. So its probably a good thing that MSG has been declared generally safe for consumption by the Food and Drug Administration.
Until recently, MSG was suspected to be the cause of Chinese restaurant syndrome in which a sense of pressure in the face, pain in the chest, and a feeling of burning in the head and upper trunk comes on 20 minutes after a meal and lasts for approximately 45 minutes. Clinical trials have shown that MSG does not produce exactly this symptom pattern, although it may occasionally cause some of these symptoms in sensitive people.
According to a report issued in July of last year by the Federation of American Societies for Experimental Biology, a respected independent scientific organization, individuals with poorly controlled asthma should be cautious, however. Research indicates that this population, which includes children with asthma, can react to as little as half a gram of MSG (approximately a teaspoonful) when it is in an easily absorbable form such as soup. The associated symptoms include headache, facial tingling, nausea and rapid heartbeat. People with high blood pressure who have been advised to limit their intake of sodium should also avoid MSG.
For those among us who may simply be sensitive to MSG, it usually takes larger doses--perhaps as much as 3 grams or more--to trigger a reaction. Most foods that are seasoned with MSG generally contain less than half a gram per serving. The likelihood of a reaction is increased, therefore, by eating large portions of these foods. The solution? Moderation. |
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