“The phase angle was the best single predictor for survival.”
The phase angle is calculated using the measurements of resistance and reactance, which are indicators of cellular health independent of weight. Normal values vary with age and gender. As the body ages the phase angle tends to decline. Therefore phase angle can also be used as a marker to track physiological aging in the body and to assess if a patient is aging well or prematurely aging. It is important to note that phase angle is dependent on patient individuality. Therefore measurements are done by comparing the patient’s phase angle to previous readings from the same patient. Any increase is seen as an improvement in cellular functioning of the body.
- Bioelectrical Impedance (BI) is composed of resistance and reactance which creates a mathematical ratio, called “phase angle”
- Phase Angle (PA) measures the health of the cells of the body
- Range of PA is 0 to 15 degrees – the higher the degree, the healthier the cells.
Range of Normal Values
There is a wide range of “normals” for phase angle within the population. Patients of smaller stature (i.e. petite females) may have a much lower phase angle than large males. The phase angle value is dependent upon both the number of cells, and the health of the cells. Therefore, two patients cannot be accurately compared to one another. It is important to guage improvement based upon comparison from your current test to your previous test.
BIA approximates physical values.
For example – a patient may have a serious health condition where the BIA values may have no significance. For example, a 33-year-old professional baseball pitcher recently died as the result of a sudden myocardial infarction. Athletic, lean, young patients typically have excellent BIA numbers. Therefore, these physical values cannot rule out the risk of heart attack, stroke, or even cancer. However, the BIA values – especially phase angle – are highly correlated with survivability from illness or injury.
The major factors that can affect phase angle are:
- mental emotional stress
- excessive physical stress
- insomnia (lack of sleep)
- toxicity from exogenous sources (sources from inside the body)
- toxicity from endogenous sources (sources from outside the body in the environment)
- poor nutritional intake or micro-waved and processed foods
- incomplete combustion cooking (excessive barbequed foods or foods cooked over flame)
- lack of vegetable intake (especially dark green leafy vegetables)
- lack of adequate water intake
- coffee and alcohol intake
- excessive sugar intake (soda pop, candy, chocolate, cookies, etc.)
- lack of exercise or movement
- frequent skipping of meals (especially breakfast)
- drug use (recreational or pharmaceutical)
A low phase angle may indicate the following:
- cell oxidative damage
- non-specific or specific inflammation
- chronic infections
- auto-immune disorders
- arthritic conditions
- liver toxicity or stress
- inadequate detoxification
- digestive issues
- chronic fatigue or fibromyalgia
- pre-mature aging
- sleep apnea or inadequate sleeping patterns
An indicator of the quantity of healthy cell membranes in the body.
Body capacitance is the absolute amount of energy storage of the body during the BIA test due to intact cellular membranes. A high capacitance indicates large amounts of intact cellular membranes. A low capacitance indicates lower amounts. Cell membranes are very important in cell function since they control what enters and leaves the cell and also control the cell activity in the body – higher intact membranes = more activity and vice versa.
Capacitance is proportional to the size of the body cell mass compartment or number of cells and to the integrity of the cellular membranes (i.e. how well the cell membrane functions). Increased capacitance is always good because it represents an increase in the number of cells, their quantity, or both. However, if capacitance is decreasing, it is important to remember that this may be due to a decrease in body cell mass related to weight loss in an otherwise healthy patient.
Related to the amount of body water. Since more water is stored in fat-free mass, a higher value indicates healthier leaner tissue.
Resistance is the effect on an alternating current that is caused by the energy dissipating the tissues of the body. Resistance is measured directly from the human body by the bioimpedance analyzer. A low resistance is consistent with large amounts of fat free mass. A high resistance is consistent with low amounts of fat free mass.
Resistance is related to water in the body. Electrolytic fluid consisting of water and charged ions contained in the body’s fat free mass readily conducts electrical current. Extracellular fluid (water and ionized sodium Na+) provides a low resistance pathway. Intracellular fluid (water and ionized potassium K+) also provided a low resistance pathway. Low resistance, indicating high conductivity, is due to large amounts of water in the body. Since water is contained solely within fat-free mass, resistance in the body is proportional to the amount of fat free mass.
The ability of cells to store energy (related to body capacitance). A low reactance indicates a breakdown in cell membranes’ selective permeability. A higher reactance means healthier cells.
The ability of cells to store energy (related to body capacitance). A low reactance indicates a breakdown in cell membranes’ selective permeability which is a result of poor cell functioning. A higher reactance means healthier cells
Reactance is the effect on an alternating current that is caused by the presence of capacitance or
the energy storage characteristic of the body due to intact cell membranes. Reactance is measured directly by the analyzer. By measuring reactance, it is possible to determine the body’s capacitance and the size and integrity of the body cell mass compartment.
A measure of total nonfat body compartments (also called lean body mass). Contains most of the body’s water
Fat-free mass, also called lean body mass, is the total amount of non-fat (lean) parts of the body. It consists of approximately 73% water, 20% protein, 6% mineral and 1% ash. Fat-free mass contains virtually all the body’s water, all the metabolically active tissues, and is the source of all metabolic caloric expenditure. The higher the fat free mass the better
“… we found that fat-free mass was lower and fat mass was higher in acutely ill and chronically ill patients than controls.”
– Journal of American Diet Assoc. 2002;102(7):944-955
The following quote from a 1997 edition of the journal Nutrition summarizes the significance of muscle mass as related to healthy aging:
“… no decline with age is as dramatic or potentially more significant than the decline in lean body mass. In fact, there may be no single feature of age-related decline more striking than the decline in lean body mass in affecting ambulation, mobility, energy intake, overall nutrient intake and status, independence and breathing.”
– Journal of Nutrition 127:990S-991S (1997)
6-Fat Mass (FM)
Amount of stored fat in the body
Fat mass is all the extractable lipids (fat cells) from adipose (fat tissue) and other tissues in the body. The higher the fat mass the lower the muscle mass which reduces the body’s metabolism. One of the most common forms of obesity is sarcopenic obesity. Sacropenia is the loss of muscle mass and the increase in fat mass. Some patients may even look slim but are “sacropenic obese”. Weight loss is not really the main issue but rather how the weight is lost in the body. Fat loss and muscle gain are far more important than just overall weight loss which can be a combination of muscle and fat loss or just muscle loss.
“Sarcopenia is the backdrop against which the drama of disease is played out: a body already depleted of protein because of aging is less able to with stand the protein catabolism that comes with acute illness or inadequate protein intake.”
– Journal of American Medical Association 286(10) (2001)
“Muscle is the major source of protein for functions such as antibody production, wound healing, and white blood cell production during illness. If the body’s protein reserves are already depleted by Sarcopenia, there is less to mobilize for illness.”
– Journal of American Medical Association 286(10) (2001)
“BIA may be clinically useful for demonstrating sarcopenic obesity in women at normal body mass indices, with additional studies necessary to determine the metabolic reasons underlying this change in body composition.”
American Journal of Clinical Nutrition 1996; 64:472S-477S
“According to most recent statistics, over 97 million Americans (61 percent) are overweight, and this number is increasing every year. Overweight is the most common type of altered body composition and is associated with a high incidence of cardiovascular disease, metabolic syndrome, hypertension and dyslipidemia. Data from the National Institutes of Health (NIH) indicate that these conditions alone account for more than $100 billion in health care expenses annually.”
Lerman et al., Body Composition and Optimal Health Applied Nutritional Science Reports, © 2002 Advanced Nutrition Publications, Inc., page 1
Consider also information from the journal, Health Affairs. “The study found that obesity — linked to health complications including diabetes, arthritis, heart disease, strokes and certain cancers — raises a person’s healthcare costs by 36 percent and medication costs by 77 percent.
Smoking and drinking also cause serious health problems, but the study, released by the journal, Health Affairs, found that active smoking leads to a more modest 21-percent rise in healthcare costs and 28-percent increase in medication costs, with smaller effects seen for problem drinkers.”
– Study: Obesity Harder on Health than Smoking, By Deena Beasley (AOL Health News) www.aol.com
7-Body Mass Index (BMI)
A ratio of weight to height used as a quick measure of health status.
Body Mass Index is a globally accepted measurement technique tat determines health risk based on the ration of your weight to height. Extra pounds translate into numerous health risks including heart disease and diabetes. BMI values from 19-25 are desirable.
Note: The results may not be an accurate representation at times since someone with a high muscle mass (bodybuilder or athelete) can score above the normal range and patients with a very low muscle mass (anorexia) can score normal. Therefore other values must be taken into consideration when looking at the BMI as a screening tool for health status.
8-Basal Metabolic Rate (BMR)
Based on fat-free mass, the number of calories your body uses each day, not counting the extra calories burned during exercise.
BMR is the minimum number of calories used by the body to stay alive with the mass that it is currently carrying. Sometimes diet programs will have a patient eat FAR less than the patient’s BMR with the hopes that this will make the patient loose weight. This often results in dramatic weight loss which may seem fine for patients, however, this is a slippery slope since most of the weight lost is muscle and very little fat. When this occurs, weight loss results in a lower body metabolism since muscle burns more calories at rest compared to fat. Patients who exhibit increase muscle loss move towards a sarcopenic state increasing the propensity to gain weight (in fat) in the future. This is why so many “fad” or “calorie restricted” diets do not work. Patients loose a lot of weight and then after a short period of time they gain even more weight back making it harder to loose each time. This may happen over and over again which is where the term “yo-yo dieter” comes from. Each time the weight drops more fat is eventually gained and less muscle is present making even harder to loose weight.
9-Intracellular Water (ICW)
Water volume of the body cell mass (i.e; water in the “inactive cells” of the body)
Intracellular water is the water volume of the body cell mass. The higher the value the more water in the cells and less water in the ECW indicating health. When the body becomes toxic it will flush water out of the ICW (inside the cells) into the ECW to dilute toxicity resulting in an increased ECW reading. It is best to have a higher ICW and a lower ECW ratio.
10-Extracellular Water (ECW)
Water volume outside the body cell mass (i.e; water in “inactive” cells of the body)
Extracellular water is the water volume outside the body cell mass. When the body becomes toxic it will flush water out of the ICW (inside the cells) into the ECW to dilute toxicity resulting in an increased ECW reading. It is best to have a higher ICW and a lower ECW ratio.
11-ICW to ECW Ratio: Movement of Body Fluids
Movement of body fluids or transudation of body fluids:
Cell membranes are semi-permeable and will allow the transport of fluid and substances across the cell membrane. “Biomembranes are thin films consisting of proteins and lipid fats. They are not rigid or impermeable but, rather, are highly mobile and dynamic structures. Membranes act as the “gate–keepers” of the cell. They control not only access of inorganic ions, nutrients, and biological compounds, but also the entry of drugs and the exit of waste products.” Medical Biochemistry, Mosby, 1999, pg 69 ISBN 0-7234-3012-8
Generally speaking, a fluid shift towards increased ICW suggests anabolic processes and improved nutrient status. Contrarily, a shift towards increased ECW suggests a decline in health status of the patient.
Consider this quote from the textbook Medical Biochemistry: (Mosby, 1999, pgs 267-268 ISBN 0-7234-3012-8) “Under physiologic conditions, the average concentration of all osmotically active substances in the ECF is 290 mmol/kg H2O, and this remains in equilibrium with the ICF. A change in the concentration of osmotically active substances in either of the water compartments creates a gradient of osmotic pressure and, consequently, movement of water between compartments.”
Note: “Osmoltically active” means substances that can pass through the semi-permeable membrane of the cells of our body
Causes of Fluid Shift:
Electrolytes provide much of the osmotically active substances of both the ECF and the ICF. Sodium is the primary electrolyte of the ECF. Potassium is the primary electrolyte of the ICF. Magnesium is the key mineral responsible for triggering electrolyte pumping into and out of the cell. A deficiency in potassium or magnesium can cause a loss of ICW. An excess of sodium can cause an increase in ECW.
Toxicity: Toxins can increase the level of osmotically active substances and therefore cause an increase in the ECW. Patients with chronic heart failure and recent onset of peripheral edema had raised concentrations of endotoxin and plasma elevations of bacterial liopolysaccharides from the death of gram-negative bacteria. (Niebauer, J, Volk H-D, Kemp M, Dominguez M, et al. “Endotoxin and immune activation in chronic heart failure: a prospective cohort study.” Lancet. 1999; 353:1838-1842)
Mitochondrial Damage: The mitochondria is the “powerhouse” of the cell and provides energy to the rest of the body. The DNA of Mitochondria is at least 10 times more susceptible to oxidative damage than the DNA within the nucleus of the cell. Mitochondrial inefficiency due to oxidative damage and / or nutrient insufficiency can be a cause of fluid shift. (Richter C, Park JW, Ames BN. Normal oxidative damage to mitochondrial and nuclear DNA is extensive. Proc Natl Acad Sci USA. 1988;85:6465-6467.)
Stress: Sodium balance is regulated via the action of the adrenal hormone aldosterone on the kidneys. Therefore, stress, by means of its impact on adrenal function, can influence fluid balance. Certainly kidney function can also influence fluid balance.
Essential Fatty Acids: The integrity of the semi-permeable cell membrane is dependent upon the lipid content of the membrane. Low levels of the essential fatty acids, or high levels of artificial fats (trans fats) can have a negative impact on membrane integrity.
Inflammation: Inflammation due to trauma, toxicity or nutrient insufficiency can contribute to increases in extra-cellular fluid. Oxidant stress can damage cell membranes. High levels of glucose through the process of protein glycation can damage cell membrane proteins and impair the efficiency of active transport.
Chronic Disease: Disease processes associated with tissue catabolism can lead to a profound shift in body fluids. Cancer is an extreme example of a catabolic illness.
Allergies: Allergic responses increase the overall body level of histamine and cause a shift of fluid from inside the cell to outside of the cell.
12-Total Body Water (TBW)
The sum of the ICW and the ECW – the total amount of water contained within the body.
The total body water is the sum total of the fluid volume of the patient. TBW is further subdivided into Intra-Cellular Water (ICW) and Extra-Cellular Water (ECW). TBW is dependent upon the hydration status of the patient as well as body composition. Lean tissue is approximately 73 percent water whereas fat tissue is approximately 10 percent water.
Consider these quotes from the medical textbook Fluid, Electrolyte and Acid-Base Balance: (Horne, Heinz, & Swearingen; Mosby, 1991.
“Water is the primary constituent of the human body. All body fluids are dilute solutions of water and dissolved substances (solutes). The average 70 kg adult male is approximately 60% water by weight, while the average female is approximately 55% water by weight.” “The percentage of body weight that is water varies with such factors as age, gender, and body fat content.”