are several ways to determine your body
fat percent. A few of the most feasible
approaches are listed below.
Life Insurance Height-Weight Tables were originally developed by this
insurance company to establish recommended weight ranges for men and women. The
"desirable" weights were those associated with the lowest death rates
among large population studies of insured people. Unfortunately, these studies
do not accurately represent a cross-section of the entire American population.
Android or "apple-shaped" obese people are more vulnerable to
disease than those who are gynic or "pear-shaped."
Waist Measurement is an additional,
independent risk factor and can be used in conjunction with any other method.
It reflects growing evidence that excess visceral fat - surrounding the
abdominal organs - on its own increases the chance of heart disease or
Research indicates that visceral fat (waist size) is more important in the
disease process than subcutaneous fat which is just under the skin ("love
handles," "pinchable inches"). Abdominal fat cells appear to
produce certain compounds that promote inflammation and may influence cholesterol
and glucose metabolism. In men, a waist size of >40" and in women
>35" is an indication of increased health risk.
Underwater Weighing when done accurately is
considered one of the best ways of determining body fat composition. However, it is impractical and not always
down with the precision necessary to achieve useful results. More often, in research underwater weighing
is used as the reference standard to confirm the accuracy of the technique in
Bioelectrical Impedance is measured when a very
small electrical signal carried by water and fluids is passed through the body.
Impedance is greatest in fat tissue, which contains only 10-20% water, while
fat-free mass, which contains 70-75% water, allows the signal to pass much more
easily. By using the impedance measurements along with a person's height and
weight, and body type (gender, age, fitness level), it is possible to calculate
the percentage of body fat, fat-free mass, hydration level, and other body
Using BIA to estimate person's body fat assumes that the body is within normal
hydration ranges. When a person is dehydrated, the amount of fat tissue can be
overestimated. Factors that can affect hydration include not drinking enough
fluids, drinking too much caffeine or alcohol, exercising or eating just before
measuring, certain prescription drugs or diuretics, illness, or a woman's
menstrual cycle. Measuring under consistent conditions (proper hydration and
same time of day) will yield best results with this method.
In Dr. Kaslow’s office, we use two devices to measure body composition – The
EIS and the Quantum unit from RJL Systems, the pioneer of bioelectrical
impedance analysis (BIA) and related sciences since 1979. Since that time RJL
has delivered more than 12,000 instruments to customers throughout the world.
In addition, more than 1,000 abstracts and peer review articles have been
written about BIA using RJL Systems instruments. RJL instruments set the
standard for body composition.
RJL Systems Quantum series assesses three compartments
of your body (fat, fat-free cells and tissue, and water) and composition with
accuracy and repeatability, which is a significant step beyond all other
analyzers. Most equipment only reports
body composition in two compartments:
fat and fat-free mass.
instruments and software assess body composition, or in other words, the different structures or parts of your body. The
BIA can measure and track changes in the amounts of body fluids, fat, and lean
body mass, which includes your muscles and organs. The BIA distinguishes where the water is
located in your body - either intracellular or extracellular. Functionally the
BIA assesses how much of your body is acting as functioning cells (called the
body cell mass or “BCM” on the report), transport tissue (extracellular mass or
“ECM” on the report) or storage cells (fat).
- Functional Mass is
where metabolic work is done and calories are burned.
- Transport Mass is
tissue that transports nutrients and oxygen to cells and removes waste
products. It has also been called
mesenchyme, the tissue matrix, etc.
- Storage Mass is the
fat where energy is stored.
Preparing for a RJL Quantum BIA:
If you haven't had a BIA
done before, it is important to be prepared.
The Quantum BIA sends a very minute electrical current throughout your
body. Although, the electrical current is so small that it is undetectable, if
you have a pacemaker or automatic implantable cardiac defibrillator (AICD), you
should not have a BIA done with an EIS or RJL Quantum unit.
- All metal jewelry should be removed. Although
you won't feel anything, metal removal improves accuracy.
- Avoid exercise or other activity that would make
you sweat at least 8 hours before your test. This is important to get
accurate body fluid results.
- Avoid caffeine or alcohol in large quantities
12 hours before the test.
- Go to the bathroom before the test to get rid
of any waste products. If you have diarrhea, it is important to tell Dr.
Kaslow, as diarrhea can affect your body fluid results.
- Your height and weight will be measured. Your
height will only be taken the first time, but your weight will be measured
each time you come in for a BIA. Since an accurate weight is important,
remember to empty out your pockets, remove your shoes and any other heavy
- You will be asked to remove your right shoe
and sock and lie down on a table.
- Two electrodes will be placed on your right
hand and two more on your right foot.
If you have a lot of hair in these areas, you may feel some
discomfort when the pads are removed.
- Once the leads are hooked up to the
electrodes, the test only takes a few seconds.
- The BIA data will be input a computer and the
results printed for review.
are several measurements of importance that are reported in the BIA results.
Phase Angle: is a measurement of your body's overall health. Phase angle is based on total
body resistance and reactance and is independent of height, weight and body
fat. Lower phase angles appear to be consistent with either cell death or a
breakdown of the cell membrane. Higher
phase angles appear to be consistent large quantities of intact cell membranes
and body cell mass. As you would expect the phase angle is increased with an
increase in body mass, even though obesity itself is not associated with good
health. All living substances have a
phase angle. In fresh uncooked
vegetables the phase angle can exceed 45 degrees. In cooked vegetables phase
angle is zero because they are dead.
Phase Angle is a
predictor of outcome and indicates the course of disease or increases as the
result of optimal health based on good nutrition and consistent exercise. Usually, a phase angle of 6 or greater is
desired for men and 5 or greater is desired for women.
As we get older our phase angle will
decrease and will be approximately 4 or less when we die. Fit adolescents may
have a phase angle greater than 10. This
effect is a result of cell integrity due to age. Low phase angles are
- Infection (HIV/AIDS, bacteremia)
- Chronic disease (cirrhosis, renal disease, pulmonary
- Cancer (most types)
- Abusive life style
- Chronic Alcoholism
- Old Age (80 - 100 years)
M. Ott, H. Fisher, H. Polat, E. B. Helm, M. Frenz,
W. F. Caspary B. Lembcke "Bioelectrical Impedance Analysis as a
Predictor of Survival in Patient with HIV Infection" J. of Acquired
Immune Deficiency Syndromes and Human Retrovirology 9:20-25 1995
R. Liedtke "Principles of Bioelectrical
Index (BMI): is a ratio
between weight and height. It is a mathematical formula that correlates
somewhat with body fat. If your BMI is
high, you may have an increased risk of developing certain diseases, including:
- Cardiovascular Disease
- Dyslipidemia (elevated cholesterol, triglycerides etc.)
- Adult-Onset Diabetes (Type II – insulin resistance)
- Sleep Apnea
- Female Infertility
is a better predictor of disease risk than body weight alone. However, there
are certain people who should not use BMI as the basis for estimating body fat
content: competitive athletes and body builders, whose BMI is high due to a
relatively larger amount of muscle, and women who are pregnant or lactating.
Nor is it intended for use in growing children or in frail and sedentary
elderly individuals. People with BMI
between 19-22 have been shown to live the longest.
energy storage compartment, Fat Mass
Fat is the energy storage mass of
the body and is the total lipid mass (triglycerides) with a density of .9
g/ml. Fat mass is equal to actual weight minus fat free mass
functional compartment, Body Cell Mass
BCM is the functional mass of the
body where work is done. All oxygen consumption, carbon dioxide production,
glucose oxidation, protein synthesis and other metabolic work takes place
within the body cell mass. The body cell mass is, in effect, the total mass
of all the cellular elements in the body, and therefore, represents the
metabolically active component of the body. In the normally nourished
individual, muscle tissue accounts for approximately 60% of the body cell
mass, organ tissue for 20% of body cell mass, with the remaining 20% made up
of red cells and tissue cells. It also contains the majority of the body's
potassium, (98 - 99%).
support compartment, Extracellular Mass
ECM is the support mass of the
body and is metabolically inactive, consumes no oxygen, produces no carbon
dioxide and performs no work. The extracellular mass consists of
extracellular fluids and tissue, such as bone and cartilage, with its primary
function that of support and transport. ECM is located outside of the
cellular compartment or outside of the body cell mass. Lean body mass is the
sum of body cell mass and extracellular mass.
Fat: this is reported both as a percentage of your
total weight and your actual body weight in pounds that is fat. Normal values are based on age and gender.
Just as you don't want too much fat, you also want to avoid too little. Having too little fat can cause your body to
stop producing important hormones. For men, this means testosterone.
Body Cell Mass (BCM): this is also reported as a percentage of
your total weight and as the actual pounds that make up cells that are active
like your muscles and organs. The body cell mass are the cells that create your
metabolism and energy. They are what
keep you healthy. When the body cell mass goes up, you are usually putting on
muscle weight. But, when it goes down, you are losing muscle mass.
ECM: stands for extracellular mass. This number is the
amount of your body weight in pounds that is made up of your skeleton and other
support structures, as well as ECW. It
is composed of tissue that is between cells.
When this number changes, it is showing that there was a change in the
ECW. This number does not show changes in bone density.
FFM: describes the combination of all cells and tissues that are not
fat, in other words, the Fat Free
Impedance Index: is another measurement of your general health.
Normal values for both men and women are greater than 1273. If your impedance
index is more than 1273, you are at a better level of health and fitness than
if it is below 1273.
capacitance: All living
things are made of cells. Cells are
membrane bounded compartments filled with a concentrated solution of chemicals
and salts. Groups of cells perform
specialized functions and are linked by an intricate communications
system. The cell membrane maintains an
ion concentration gradient between the intracellular and extracellular
spaces. This gradient creates an
electrical potential difference across the membrane which is essential to cell
survival. Electrical gradients are
necessary to support movement of oxygen, carbon dioxide, and nutrients. Therefore, the cell membrane has electrically
insulating qualities or capacitance.
capacitance will increase or decrease depending on the health and the number of
cells. Damage to the cell membrane, and its functions, is as lethal to the cell
as direct damage to the nucleus itself.
membrane functions as a permeable barrier separating the intracellular
(cytoplasm) and extracellular components. The lipid membrane is transversed by
proteins, which are soluble in water thus making pores through which water,
ions and other chemicals can enter and exit the cell.
capacitance is somewhat like phase angle, whereas it is not affected by weight
or body fat. It is a measure of cell membrane health in all living substances
and can change dramatically depending on disease or good health. A body builder, for example, would have a
high parallel capacitance and low resistance, or more cell volume, because he
is extremely muscular and fit. A malnourished AIDS patient would have a low
Basal Metabolic Rate (BMR) is how many
calories are burned at rest during the average day. The metabolic rate is determined by how many
cells are producing oxidative energy.
The more cells, the more energy, and the higher the basal metabolic
rate. Thyroid, other hormones,
medications, etc. all can affect the basal metabolic rate. A low basal metabolic rate means that any
calories you consume above your unique basal metabolic rate are unnecessary to
supporting you and will be converted into storage (fat). A low
body temperature would occur if your rate of calorie burn is too low. If you consume a lot more calories than you
need, then you may have an excessive appetite problem, which can be due to a neurotransmitter imbalance.
occurs in two distinct and interdependent phases: 1.) catabolism, in
which the body breaks down food into its component parts and harvests the
energy stored in its atomic bonds, and 2.) anabolism, in which those
component parts and energy are used to build new tissues and conduct basic life
functions. Basal Metabolic Rate (BMR) is the amount of energy your body
requires every day to perform its most basic function including:
- Heart beating
- Muscle activity
- Transportation of fluids and tissue
- Circulation of blood
is the amount of energy you would require if you laid in bed all day without
ever moving a single muscle. Since most of us do a bit more than that, a daily
activity level must also be factored in. This ranges from everyday activities
to working out strenuously. BMR varies
between the sexes. Lean body mass is a
major determinant. Because women tend to
have less lean muscle mass, their BMR is lower than that of otherwise
comparable males. BMR is at peak during
infancy, then declines rapidly through childhood and adolescence. It continues to fall slowly with increasing
age and decline further with old age largely due to a loss of muscle mass. However, this is not inevitable, because
weight-bearing (resistance) exercise will prevent or reverse muscle loss among
Fluid Assessment: is described in the section called Total Body
Water Compartments, which tells about the fluid level and distribution in your
body. The fluid is actually primarily
water. Your total body water (TBW) is
measured in liters (L) and is made up of:
Water (ICW): the fluid inside all
of your body’s cells. The cells of your
muscles and organs (liver, kidney, brain, etc) contain more water than fat
cells. The closer to ideal your ICW, the
greater the number of cells that contribute to your metabolism.
Extracellular Water (ECW) is the fluid
that circulates outside your cells and throughout your body. This includes your
blood, lymphatic tissue, and the ECM discussed previously. It should be noted that oxygen delivery to
the cells is markedly reduced when there is excess extracellular water (edema).
Total Body Water (TBW): If
you are dehydrated or losing a lot of fluid, your total body water may be low.
If you are retaining fluid or have an infection, your total body water may be
elevated compared to ideal.
Water Compartmentalization is among the most valuable features of the BIA
since it tells how much water is in the cell and how much is outside of the
cell. The water content inside the cell
(“intra-cellular water”) is termed the “ICW” and the water content outside of
cells (“extra-cellular water’) is termed the “ECW.” The total body water content is called
“TBW.” These three values implicate:
integrity of the cell membrane, which is responsible in part for the
electro-osmotic gradient across the cell membrane. The content of the intracellular environment
must be in balance with the surrounding tissue in order to function properly in
terms of cell nutrition and detoxification.
electrolyte content inside the cell. In
order to hold the water inside the cell, electrolytes must be in sufficient quantity
to provide the osmotic pressure for water to stay inside the cell. Potassium is one of the major intra-cellular
electrolytes whereas sodium is one of the major extra-cellular electrolytes.
The fatty acid
content of the cell membrane. If we did
not have a lipid layer around every cell in our body, all of the water would
leak out. The fat repels the water (like
oil and vinegar) and helps keep water within the cell.
The amount of
mesenchyme or tissue that has built up with water. Usually this represents toxicity since
normally there should be only a modest amount of tissue separating the cells
from each other and from blood vessels, nerves, etc. Often times this reflect the amount of ECM