Editor’s Note: This post was updated on October 18, 2018, for accuracy and comprehensiveness. It was originally published on July 5, 2017.
When it comes to body composition testing and analysis, most people instantly think of body fat percentages and muscle mass . Yet today’s medical BIA (bioelectrical impedance analysis) devices do so much more than just measure body fat and muscle mass.
Body fat percentages are only one part of a complete body composition analysis. For body composition devices using Direct Segmental Multi Frequency-BIA technology (DSM-BIA), you can also measure and track other valuable indicators of your health like your visceral fat, body water distribution, segmental readings, and phase angle values.
Although your body fat percentage can be a strong indicator of your overall health and current state of your body composition, the aforementioned outputs are equally useful metrics that can help predict or detect health issues.
In this article, let’s go beyond the usual discussions on body fat and muscle mass when it comes to body composition. Read on for a in-depth explanation about your Phase Angle (PhA) – one of the most valuable, and misunderstood, health indicators provided by medical grade BIA devices.
What’s Phase Angle Anyway?
In his book The Water Secret: The Cellular Breakthrough to Look and Feel 10 Years Younger, celebrity dermatologist and skin care expert Dr. Howard Murad writes:
PhAs have given us a remarkable window into how the body responds to changes in health — for better or worse. This explains why people with illnesses such as HIV or cancer, or those who are nutritionally deficient, routinely exhibit low PhAs. As expected, PhAs also decrease with age as your body loses its capacity to repair and return over new cells as quickly as it did in its youth. The true age of a human being can be determined by the changes in the Phase Angle.
Furthermore, he elaborated:
The Phase Angle goes up when you’re healthy and down when you’re ill. It also goes down as you age. When you increase your Phase Angle, you slow down aging.
Slow down aging, did that catch your attention? But before we get to that, we need to learn the basics of PHa by reviewing the established facts and research.
Demystifying Phase Angle
Your PhA is a direct measurement of your cell integrity and the distribution of water within and outside the cell membrane. In his book Supercharge Your Cell Vitality, author Dr. Greg Barsten refers to PhA as merely a fancy name for cell membrane health.
Cell membranes hold in the important parts of the cell and also regulate what comes in and out. Think of this regulation like a fortress drawbridge.
In healthy humans, the cell membrane consists of a layer of non-conductive (insulator) lipid material sandwiched between two layers of conductive fluids (body water). When there are two conducting materials surrounding an insulator, we often refer to this insulator as a capacitor. That said, your cell membrane is like a fortress with capacitor-like capabilities that not only try to prevent currents from entering the cells but also other unwanted materials like toxins and waste. What this means is that healthy cells (or stronger capacitors) are better at preventing these unwanted substances from entering cells.
How is Phase Angle Measured?
In BIA, PhA is the relationship between resistance and reactance.
To understand these variables, you have to understand what lean body mass and body cell mass means.
Your Lean Body Mass (LBM) is the total weight of your organs, skin, bones, body water, and muscles. It describes the entire weight of your body minus your body fat. This is why it’s also often referred to as fat-free mass.
On Resistance, Reactance, and Impedance
Resistance happens when a conductor transfers the energy of (or moves) an electrical current. The greater the conductor, the lower the resistance. In the human body, low resistance is associated with large amounts of LBM. High resistance is associated with smaller or low amounts of LBM.
Body fluids consisting of water and charged ions readily conducts electrical currents. Both extracellular water or ECW (water and ionized sodium Na+) and intracellular water or ICW (water and ionized potassium K+) provide a conductive pathway. When a person has a lot of lean body mass, they have a lot of body water, meaning greater conductivity of the current and less overall resistance.
It’s also worth noting that resistance in the body is proportional to one’s LBM because water is contained solely within your LBM. The unit of measurement for resistance is ohms.
Reactance, on the other hand, gauges your cells’ ability to store energy. Your body has high reactance if your cells can store energy easily and it has low reactance if it stores energy poorly. Cells that are “healthy” or those with intact cellular membranes hold the electrical energy charge “longer.”
For this reason, your body reactance is proportional to both the amount and strength of the cells in your body. Like resistance, the unit of measurement for reactance is ohms.
Impedance is the sum of resistance and reactance, but when evaluated trigonometrically, the relationship between resistance and reactance creates a ratio. This ratio is your PhA and is expressed in degrees.
You can measure your PhA and cell health using a Bioelectrical impedance device that sends electrical currents is used to assess cell membrane health. Impedance is measured by introducing a small alternating current into the body and measuring the effects on the current caused by the body. In humans, 50 KHz is considered ideal to maximize reactance and determine the point where cells are strongest at resisting the current (thus creating the highest PhA).
As the current travels in your body, your body water will naturally resist the flow of the energy current as it travels and this is referred to as resistance. To keep it simple, when the current encounters a cell, the cell wall will cause a “delay” as the voltage builds up enough energy to pass through the cell wall while the current continues instantaneously. The brief time delay caused by the cells is compared to the amount of water, providing us with a PhA, in degrees. Impedance is a combination of these two values.
Why You Should Care About Your Phase Angle
What does PhA have to do with your overall health?
By tracking your PhA, you’ll be able to gain a more precise picture of your health because it examines cell integrity health and the amount of water inside them.
Based on established research findings, higher PhA values suggest greater cellular integrity and reflects better overall cell health. A low PhA, on the other hand, is highly predictive of decreased muscle strength, impaired quality of life, and increased mortality in old adults with cancer. Low phase angles tend to be consistent in individuals with malnutrition, HIV/AIDS infection, cancer (discussed in detail below), chronic alcoholism, and old age.
Thus, keeping your pHa high through healthy lifestyle habits is encouraged.
How do you know if you’re PhA is within normal values or not?
This is where things get interesting.
While it has been shown that certain factors can influence one’s PhA (age, gender, and BMI), it has been shown that there are considerable differences between phase angle reference values across different populations. These differences are not only explained by age or BMI and may be due to differences between impedance analyzers.
In short, PhA values tend to differ based on the BIA device you’re using. In clinical practice, multi-frequency- and segmental-BIA may have advantages over single-frequency BIA in these conditions, but further studies and validation are still required.
Below is an example of PhA reading using InBody’s 770 model.
Phase Angle Reading Example:
Finally, it’s important to note that phase angle is dependent on every person’s individual makeup. To gauge progress, comparing your current phase angle readings to your previous readings is more important than comparing your PhA values with someone else’s.
Your Body Composition and Phase Angle: What’s the Connection?
Can improving your body composition help increase your phase angle values? It sure does.
A 2016 study revealed that age plus a combination of FFM (fat-free mass) and height were the most important variables that influence PhA variability among healthy subjects. The same research concluded that the ECW:ICW ratio may justify the variations shown in PhA when it comes to several clinical situations and severe obesity. When someone has inflammation or edema (causing a higher ECW/TBW), the health of their cells (and their phase angle) will be negatively affected.
Based on the study’s results, you are likely to increase your chances of improving your cellular health and PhA values if you take steps towards improving your body composition, whether it’s through nutrition, exercise, or a combination of both.
Other lifestyle factors that are most likely to impact phase angle variability include but are not limited to:
- Toxicity exposure
- Consumption of highly processed meals
- Lack of quality sleep
- Stress (physical, mental, and emotional)
- Lack of consistent physical activity
- Excess intake of coffee, alcohol, and refined sugar
The same research concluded that the ECW:ICW ratio may justify the variations shown in PhA when it comes to several clinical situations and severe obesity.
In a healthy body, an ICW:ECW ratio of 3:2 is considered ideal. However, certain health conditions like renal disease, chronic inflammation, and even increased body fat mass in obesity (due to disruption of one of your body’s hormone systems (the renin-angiotensin-aldosterone system) can potentially cause your ECW to go up.
For instance, patients with symptoms associated with heart failure have a limited ability for the heart to circulate blood, causing edema. Edema is irregular swelling caused by accumulation of fluid in certain tissues within the body. When this happens, PhA values will likely go down because the pressure from excess ECW causes cells normal functions to become compromised. In fact, phase angle seems to be an independent prognostic marker in patients with ADHF (acute decompensated heart failure) because of fluid retention. For the cells to function properly, it’s important to maintain or restore ideal (or near ideal) ECW (or extracellular) balance.
The link between your phase angle values and body composition can be summarized through the following:
Increased phase angle may be a result of:
- Gains in muscle mass
- Loss of inflammation and reduction of body fat
Decreased phase angle may be a result of:
- Loss of muscle tissue
- Increased inflammation
But wait, there’s one caveat: an increase in PhA is not always a good thing, nor should a decrease in your PhA values always be frowned upon.
Phase Angle: Implications for Clinical Practice
In regards to PhA’s use in clinical settings, research literature and data reveal the following:
A 2012 study found a significant association between low PhA and increased nutritional risk, increased hospital length of stay and non-survival. The researchers concluded that gauging PhA values can help quickly identify patients who are at nutritional risk at hospital admission. This will help save time on the hospital staff’s end (and possibly save the patient’s life) because they can forego in-depth nutritional assessments by doing a quick BIA test instead.
Another set of studies came up with identical conclusions. This time around, the implications of PhA to a patient’s nutritional status are more specific. It turns out that bioimpedance-derived PhA can be a potential nutritional indicator for patients with advanced colorectal cancer and breast cancer.
Finally, a research paper presented at the 2011 AAAI (Association for the Advancement of Artificial Intelligence) 2011 Spring Symposium suggested that phase angle is an independent indicator of prognosis in cancer (of most types) because it illustrates cell membrane integrity and function that may not be possible with other approaches that gauge prognosis. In fact, the paper suggested phase angle-based biometric scoring systems for determining prognosis among cancer patients. This is good news because BIA is quick and noninvasive in comparison to tools and tests used in cancer prognosis.
Your PhA values can clue you in with what’s going on in your body. It can help identify health risks and address existing health issues and help track progress of lifestyle changes (diet and exercise). For most people, it has helped them make data-driven health and wellness decisions. Medical practices also use it to personalize a patient’s health care plan.
However, keep in mind that your PhA values are only part of the equation when it comes to assessing the current state of your health.
The rest of the body composition outputs (body fat, muscle mass, body water ratio) are equally valuable so finding a BIA device that can provide more detailed outputs is crucial. For instance, changes in your body fat percentages can be tricky to explain if the only outputs you have are merely body fat mass and fat-free mass values. For more accurate results, make sure you choose your BIA device wisely.
Kyjean Tomboc is a nurse turned freelance healthcare copywriter and UX researcher. After experimenting with going paleo and vegetarian, she realized that it all boils down to eating real food.