Wednesday, 27 February 2013

Body Composition Analysis

Body Composition Analysis

body composition analysis
By   Masters in Exercise and Sports Science

With the number of people who are overweight or obese continuing to grow, body composition analysis is gaining more traction as the best measure of assessing health based on body size. Unlike weight or body mass index (BMI), body composition analysis looks at the percentage of fat mass and fat-free mass a person is carrying to gauge whether a person should be classified as underweight, normal weight, overweight or obese.

Understanding Body Weight, BMI and Body Composition

Body weight, BMI and body composition are all assessments of body size, but they're not created equal! Here's what you need to know:

Body Weight

Body weight is the most commonly used assessment of body size because it's so easy to measure and track. Face it, almost everyone has a bathroom scale in their home! The ease of measuring body weight is quite possibly its greatest benefit, but body weight is not the best predictor of health. This is because weight only provides a measure of how gravity works on a mass. It can be affected by hydration, menstrual cycles, food intake and more. Body weight cannot provide information about what's going on inside the body, but it can be helpful when used as a general guideline as long as it's not being perceived as a true indicator of health.

Body mass Index (BMI)

BMI is a slightly better assessment of health because it's used to predict "normalcy" based on height and weight. While it's still only moderately correlated with body fat percentage and markers of disease, one added benefit is that it removes the obsession some people associate with the scale. It's extremely easy to calculate BMI online using a BMI calculator, but it's also relatively easy to calculate by hand, as long as you know your height in meters and your weight in kilograms:

Calculation: BMI= Body mass (kg) / Stature (meters squared)

Unfortunately, BMI still doesn't provide real information about body fat percentage or body fat distribution, which can lead to problems. It is possible for a person with a healthy body fat percentage to be considered overweight or obese, based on BMI, and it's also possible for a person with an unhealthy body fat percentage to be considered normal weight, based on BMI.

Body Composition

Body composition is analyzed and predicted in a number of ways, each with pros and cons. The real benefit of looking to body composition analysis rather than weight or BMI is that it takes into account percentage body fat and body fat distribution, both of which are strongly correlated with markers of disease.Some methods of analyzing body composition are just as simple as measuring body weight and BMI, but these tend to be slightly less accurate than the more difficult methods of analyzing body composition. All-in-all, if you have the opportunity to track your health and fitness progress based on body composition rather than weight or BMI, you should take advantage of the opportunity to do so.

Understanding Body Fat

Fat gets a bad wrap. The fact is, people need fat. It provides fuel for movement, cushions the bones, joints and organs, provides warmth, carries vitamins and minerals and even helps depress appetite. Everyone needs a certain amount of body fat just to survive!

When you test for body composition, you're basically assessing how much fat you have in your body, how much of that fat is storage fat, how your fat is distributed and how these factors compare to markers for disease. Based on this assessment, your body fat percentage and distribution can more accurately place you into an underweight, normal weight, overweight or obese category.

Essential Fat

Essential fat is the fat you must have in your body to perform basic human functions. This is the fat found in the heart, lungs, liver, spleen, kidneys, intestines, muscles and lipid-rich areas of the brain and spine. Women have an additional amount of essential body fat termed sex-specific essential fat. This extra essential fat plays a part in hormone regulation and child bearing, and can be found in the breasts, pelvis, hips and butt. In order to ensure essential fat reserves are maintained, minimal leanness standards typically recommend that men maintain no less than 3% body fat, while women should maintain no less than 10 to 12% body fat. While there are exceptions to this rule, women who become leaner than 10 to 12% body fat may start seeing disruptions to their menstrual cycle that could contribute to other health problems like bone mineral loss and stress fractures.

Storage Fat

Storage fat is the fat that a person carries in excess of essential fat. Carrying storage fat is normal and healthy as long as you don't carry too much! This fat is carried primarily in adipose tissue, although it also accounts for the visceral fatty tissues that protect the organs in your abdomen. Healthy men and women carry a similar amount of storage fat (12% and 15%, respectively) in addition to essential fat reserves.

Healthy and Unhealthy Levels of Body Fat

Generally speaking, the acceptable standards of fatness for men and women are 20% and 30%, respectively. This means that men who have greater than 20% body fat, and women who have greater than 30% body fat are at a higher risk of heart disease, diabetes and other related diseases than individuals who maintain a lower body fat percentage.

Distribution Plays a Role

While total fat percentage is important, how it's distributed can also predict risk of disease. Individuals who carry more fat around their abdomen (the "apple" shape) are at a higher risk of heart disease, stroke and diabetes than those who carry fat in their hips, buttocks or thighs (the "pear" shape). Unfortunately, where you tend to gain weight can be genetic, so if you tend to put on weight around your waist, tracking your waist circumference with a tape measure can help you monitor your risk of disease. The American Cancer Society (ACS) considers a healthy waist size for women to be less than 30 inches, while men should keep their waist size below 35 inches. These numbers are lower than the numbers suggested by the American Heart Association, but according to a study performed by the ACS, for every four-inch increase in waist circumference above their sex-specific recommendations correlated with a 25 percent greater risk of death.

Body Composition Analysis Methods

Depending on how accurate you want your body composition analysis to be, you can opt for home-based or lab-based analysis methods. Home-based methods include those commonly performed at gyms and fitness centers that do not require extensive high-tech equipment.

Home- or Gym-Based Analysis Methods

The most common home or gym-based body composition methods include the following:
  • Girth measurements
  • Skin fold testing
  • Bioelectrical Impedence Analysis (BIA)
With the exception of BIA testing, it's helpful to have a trained exercise specialist perform these analysis methods. This is because accuracy varies significantly with human error, and you're most likely to get an accurate result if the test is performed by someone trained to provide the analysis. This may seem like a hassle, but almost every gym, fitness or recreation center has trained staff on hand to provide the tests at zero or minimal cost.

Lab- or Hospital-Based Analysis Methods

The most common lab- or hospital-based body composition methods include the following:
  • Dual-energy X-ray Absorptiometry (DXA)
  • Hydrostatic Weighing
These methods provide a much more accurate assessment of your body composition, although some are more practical to perform than others. Check with your local hospital or university to see if they offer testing. Many locations do, and you can expect to spend anywhere from $30.00 to $200.00 per test, depending on the test and the organization providing the testing.

Also keep in mind that body composition can be determined by MRI and CAT scan. If you are having one of these tests performed for another condition, it doesn't hurt to ask if you can get your body composition numbers as well.

Pros and Cons of Body Composition Analysis Methods

Each method of body fat analysis carries pros and cons. When deciding which method to pursue, you want to consider factors like cost, ease of analysis, your own personal comfort level, the test's accuracy, and whether you're interested in just body fat percentage or body fat percentage and distribution. Consider the following pros and cons:

Girth Measurements

Girth measurements involve using a tape measure to measure the girth at various body sites. It's relatively quick and easy, but isn't as accurate as other measures.
Pros:
  • Minimally-invasive, can be performed at home or in a gym setting
  • Simple calculation method
  • Possible to perform on yourself
  • Helpful for tracking body fat composition and distribution, especially when monitoring changes during exercise programs if you're more interested in overall changes than accuracy
  • Especially helpful for obese or super-obese individuals, as obesity can effect the accuracy of other testing methods
Cons:
  • Not as accurate as other forms of measurement, only accurate to within 2.5 to 4 percent
  • Room for human error, especially when performing self-measurements
  • Psychologically difficult for some individuals who don't like having their girth assessed
Girth measurements are often used in conjunction with other, more accurate testing measurements.

Skinfold Testing

Skinfold testing involves using skin calipers to "pinch" body fat at various sites on the body. It's relatively quick and easy, but isn't as accurate as other measures.
Pros:
  • Minimally-invasive, most commonly performed in a gym setting, sometimes in a lab
  • Fairly simple calculation method, especially when using a computer system
  • Helpful for tracking body fat composition and distribution, especially if the test is always performed by the same individual to reduce the likelihood of error
Cons:
  • Not as accurate as other forms of measurement, only accurate to within 3 to 5 percent
  • Must be performed by someone else
  • Room for human error, especially when performed by an untrained individual
  • Some people are averse to having their skin "pinched" by calipers
  • Is less accurate in individuals with higher body fat percentages

BIA

BIA is quite possibly the simplest ways to predict body composition. In fact, if you have a bathroom scale that offers a body fat monitor setting, you're already using BIA analysis. Unfortunately, it's one of the least accurate forms of measurement.
Pros:
  • Non-invasive
  • Can easily be performed at home in a private setting, as long as you have the proper equipment (hand-held or scale-like monitors are available)
  • Helpful for monitoring body composition
Cons:
  • Widely varying accuracy, based on factors like hydration, ambient temperature and changes in menstrual cycle
  • Tends to be one of the least accurate forms of measurement
  • Cannot track body fat distribution

DXA

DXA must be performed in a lab setting, and due to the high-tech equipment used, it's often the most expensive option. On the other hand, it's also the most accurate option available.
Pros:
  • Non-invasive
  • Provides extremely accurate assessment of body composition, fat distribution and even bone mineral density
Cons:
  • Can be expensive (depending on where it is performed), making it impractical for regular scans
  • Must be performed by a trained professional at a lab

Hydrostatic Weighing

Hydrostatic weighing is also very accurate, but the cost and the method of analysis are sometimes deterrents. During hydrostatic weighing, you have to completely submerge yourself in water in order to obtain accurate results. While this may not bother some people, it can really scare others.
Pros:
  • One of the more accurate measurements of body composition, usually accurate to within 1.5 percent
Cons:
  • Must be performed by a professional in a lab setting
  • Can be expensive (depending on where it is performed), making it impractical for regular analysis
  • Can be extremely difficult for individuals who don't feel comfortable with full-body water submersion; this discomfort can affect the test's accuracy
  • Can seem tedious when compared to other methods of analysis

Calculating Body Fat

For skinfold and girth measurements, you can easily calculate your body fat by plugging your results into online calculators. The other forms of body fat calculations must be performed by trained professionals. Be sure to read more about how body fat is calculated so that you're amply prepared when you set up an appointment with a health or fitness professional.
Posted by at
Labels: