Body Fat % Approach to Determining Your Optimum Weight

An individual's body fat percentage is a measure of the average percentage of fat that an individual's body is carrying. In order for an individual's body to function appropriately, it is imperative that their body contain a healthy level of body fat.

Contrary to popular belief, body fat, when maintained at an appropriate level, is not the enemy. However, when an individual's percentage of body fat exceeds the recommended levels as stated by the medical industry, the human body becomes susceptible to a whole host of debilitating diseases. This is true on the other end of the spectrum as well, as too little body fat can be equally as dangerous.

Body fat is responsible for regulating the human body's temperature, providing a cushion and a layer of insulation for all internal organs, and is the main mechanism used for storing the body's energy. In other words, it is paramount to good health that an individual maintain an appropriate percentage of body fat.

When most individuals state that they want to lose weight, it is implied that they want to lose body fat. It is recommended that each individual seeking to lose weight take the time to first calculate their body fat percentage. Once an individual has calculated their body fat percentage, they should compare their value to the recommended levels of body fat listed below in Chart #1. Notice that the body fat percentages in the chart are divided into underfat, athletic, fit, healthy, overfat and obese.

Calculating Your Optimum Weight Based on Body Fat

As an example, we'll determine the range of appropriate body fat percentages for a female that is 35 years of age. As depicted in Chart #1, a typical healthy woman of 35 years of age should have a percentage of body fat that ranges from 20% (low end of athletic) to 33% (high end of healthy). To further the example, lets say that the 35-year-old woman currently weighs 146 pounds and has a 38% level of body fat. More specifically, this means that her body consists of 55.48 pounds of body fat and 90.52 pounds lean body mass (bone, muscle, organ tissue, blood, etc.). Next, we'll determine the healthy percentage of body fat upon which a 35-year-old woman should base her weight loss goals.

Example: 35-year-old Female, 146 pounds, 38% body fat

Total body weight comprised of body fat: 55.48 pounds

Optimum percentage of body fat: 20% (low end of athletic) to 33% (high end of healthy)

Amount of body fat (in pounds) at a 20% level = 0.20 (body fat % goal) X 146 (current weight) = 29.2 pounds 

Amount of body fat (in pounds) at a 33% level = 0.33 (body fat % goal) X 146 (current weight) = 48.18 pounds

Hence, the calculations indicate that in order for a woman 35 years of age to have a healthy percentage of body fat, she should have no less than 29.2 pounds of body fat and no more than 48.18 pounds of body fat.

Optimum weight at 20% body fat level = 90.52 (lean body mass) + 29.2 (20% body fat) = 119.72 pounds 

Optimum weight at 33% body fat level = 90.52 (lean body mass) + 48.18 (33% body fat) = 138.7 pounds 

In conclusion, the subject should set her weight loss goal to achieve a total body weight that is between 119.72 and 138.70 pounds. She should therefore lose between 7.30 and 26.28 pounds of overall body weight. It should be noted that losing more than 26.28 pounds in this example would be an unsafe practice, and is not recommended.

Calculating your body fat percentage prior to determining your personal weight loss goals is a recommended approach, and will assist in determining whether your weight loss goals are realistic as well. Instead of just stepping on a weight scale and deciding how much weight you want to lose, it's better to determine your current body fat percentage and then calculate the amount of weight you would like to lose based on the healthy range of body fat percentages for your sex and age. In other words, before you decide that you need to lose 20 pounds, remember that your body weight consists of both lean body mass and body fat.

The percentage of body fat that an individual has or lacks can be potentially dangerous to their health. Carrying too high of a body fat percentage may increase an individual's risk of developing serious health issues such as high blood pressure, high cholesterol, heart disease, diabetes and cancer. However, carrying too low of a body fat percentage deprives your body of temperature stability, stored energy and organ protection, and can potentially cause your body to enter a state of catabolism, which is when the body begins to consume muscle protein for energy.

Determining Current Body Fat Percentage

There are several approaches an individual can utilize to determine their percentage of body fat, and thereafter their optimum weight. This section will briefly discuss the most common methods and techniques used currently to determine an individual's percentage of body fat.

Skinfold Caliper

Skinfold calipers are likely the most popular technique used to determine an individual's percentage of body fat. Skinfold calipers measure skinfolds by pinching the skin together in specific locations to determine how much subcutaneous fat (fat under the skin) an individual's body contains.

The individual or medical practitioner then enters the resultant numbers into an equation to predict body density and body fat percentage. It is important to remember that skinfold calipers do not measure an individual's body fat percentage directly.

The most common areas of the body used to perform the skinfold caliper measurements, to determine body fat percentage, are as follows:

1. For men, use a diagonal pinch halfway between the armpit and the nipple. Women need a diagonal pinch one-third of the way from the armpit to the nipple.

2. A vertical pinch on the midaxillary line which runs directly down from the center of the armpit. Raise your arm above your head and have your partner get these skinfold measurements just below the level of your nipple.

3. A diagonal pinch just above the front forward protrusion of the hip bone.

4. A vertical pinch about one inch from your belly button.

5. A vertical pinch halfway between the knee and top of the thigh.

6. A vertical pinch halfway between the shoulder and the elbow.

7. A diagonal pinch directly below the shoulder blade.

Skinfold caliper measurement tips

• Take skinfold caliper measurements while standing.

• Take all skinfold caliper measurements on the same side of the body, preferably the right side.

• Pinch the skin between your forefinger and thumb. Pinch deep enough to get the fat but not so deep that you start pulling muscle up.

• Place the skinfold calipers less than a half-inch from your pinch, midway between the crest and the base of the skin that is being pinched.

• For each of the skinfold caliper locations, take three measurements and calculate their average. However, do not take the three measurements at the same location consecutively. Instead, complete all seven measurements and then start over.

NOTE: When using the skinfold caliper technique, consistency and repeatability are key. Always have the same person take the measurements, and make sure to always take the skinfold caliper measurements in the exact same locations. 

Once all measurements have been taken (three times at each location and averaged), it is time to calculate the percentage of body fat. There are currently over 100 equations used to calculate an individual's percentage of body fat. Each equation relates to a different subset of individuals with different physical characteristics. For example, young people store approximately one half of their body fat directly under the skin. However, as individuals age, a greater proportion of their body fat is stored internally. Additional differences can be found in one's gender, fitness level, race, and the current amount of total body fat a person has.

Using the skinfold caliper technique to determine an individual's percentage of body fat provides an accuracy level of plus/minus 4%. Hence, a body fat percentage calculation of 20%, factoring in a 4% margin of error, would support a body fat percentage between 16% and 24%. However, as long as the skinfold caliper measurements are taken with a high level of repeatability, the body fat percentage value will be a relatively accurate measure and can effectively be used to monitor an individual's body fat percentage.  

Bioelectrical Impedance Analysis (BIA)

Bioelectrical Impedance Analysis, or BIA, is currently one of the most exact and accessible methods of determining an individual's percentage of body fat. In performing conventional BIA, a person is weighed, then height, age, gender and other physical characteristics such as body type, physical activity level, ethnicity, etc. are entered into a computer. While an individual is lying down, electrodes are attached to various parts of their body and a small electrical signal is circulated throughout their body.

BIA measures the impedance or resistance to the electrical signal as it travels through the water that is found in muscle and fat. The more muscle a person has, the more water their body can hold, and the easier it is for the current to pass through it. The more fat an individual has, the higher the resistance to the current.

BIA body fat tests are safe and do not inflict any pain. In fact, the electrical signal used in the BIA test cannot be felt by adults or children.

Today, it is no longer necessary to visit a medical practitioner for a BIA body fat percentage analysis. There are several companies that manufacture weight scales that include BIA capability. In fact, BIA scales perform the calculations instantaneously, and can even upload data to your personal computer for review and storage. The typical cost of a BIA scale is under $100. With the BIA scale method (similar to the industrial BIA machine), the device sends a small electrical signal through your hands or feet and uses the data to determine how much of your body is fat and how much is water, since muscle and lean tissue are primarily composed of water. To perform the body fat calculation, an individual only needs to enter their gender, age and height.

DEXA Scanning

DEXA stands for "dual energy x-ray absorptiometry," and is typically simplified as DXA. DEXA is primarily used to measure bone density and lean mass, but can also be used to produce fat mass readings. The DXA system utilizes a body scanner, takes approximately 15 minutes to run, and costs upwards of $100 per session. The DXA scanner is fairly accurate and typically delivers results within a 2% to 3% error margin. Check with your doctor to determine whether this method is appropriate. Thereafter, call your insurance company to ask whether this test is covered under your current health insurance policy.

Hydrostatic Weighing

Hydrostatic weighing consists of submerging an individual completely underwater while they sit on scales and expel all of the air from their lungs. Similar to the DEXA technique of determining an individual's percentage of body, this approach has a margin of error of approximately 2% to 3%.

The technology utilizes the displacement of water and the differing densities of fat and lean muscle mass, and is considered to be very accurate. However, very few establishments have a hydrostatic weighing system, limiting accessibility for the general public.

The process of determining an individual's percentage of body fat using the hydrostatic weighing approach is as follows:

• An individual sits on a scale inside a tank of water and blows out as much air as they can.

• The individual is then submerged underwater and asked to expel even more air. Since fat is lighter than water, the more fat the individual has, the more they will float.

• The scale measures underwater weight to determine the individual's body density. The margin of error is typically 2-3%, though accuracy depends on the amount of air the individual expels. In other words, the individual must exhale all of their air or accuracy will be reduced.

This is a difficult way to measure body fat since it can be uncomfortable and many individuals feel uneasy with being asked to expel all of the air in their lungs while being submerged underwater. In addition, the difficulty in finding a medical facility or university that provides this service makes this approach less accessible. 

The Bod Pod

The Bod Pod system is an air displacement plethysmograph which uses whole-body densitometry to determine body composition (fat and fat-free mass) in adults and children. It is a complete system based on the same operating principle as hydrostatic weighing, except that the Bod Pod uses air displacement plethysmography instead of water for highly accurate, fast and safe results. The Bod Pod also offers information on an individual's resting metabolic rate (RMR) and total energy expenditure (TEE) as optional components of every body composition test. This data is gathered without requiring the individual to perform any additional testing maneuvers, and a complete assessment requires only about 5 minutes.

In comparison to other body composition assessment methods, the Bod Pod's air displacement plethysmography has eliminated the invasiveness of Dual Energy X-Ray Absorptiometry (DEXA), as well as the difficulties associated with hydrostatic weighing. The Bod Pod can be used with most types of individuals, including children, the elderly, the obese and those with physical disabilities.

Although this technique is highly accurate, the cost associated with conducting this type of body fat analysis, coupled with the difficulty of finding a medical professional that provides this service, makes this approach less accessible. 

Conclusion

As this article has detailed, there are several viable approaches to determining an individual's body fat percentage. The intent of determining an individual's percentage of body fat is to appropriately define the healthy and optimum body weight of the individual.

It is the belief of this website that the primary factor associated with an individual's body is not their specific weight, but their percentage of body fat and their specific body measurements.

However, this being said, there is a correlation between an individual's body weight and their percentage of body fat. By determining your percentage of body fat, you can then reference Chart #1 to determine your optimum body fat percentage range. 

Thereafter, you will be able to appropriately define your specific fitness goals. Once you have defined your specific fitness goals, you will be ready to create a fitness routine that will facilitate a healthy way of life.