How to Calculate Body Fat Percentage Using 3 and 7 Skinfold Measurements
Body fat percentage is an important measure to assess body composition and overall health. The calculation of this percentage can be done through the skinfold method, which involves measuring skinfold thickness in different areas of the body. We will explain step by step how to calculate body fat percentage using 3 and 7 skinfold measurements in a simple way.
How to Calculate Body Fat Percentage Using 3 Skinfold Measurements:
Step 1: Choose Measurement Areas
In the Pollock method, the three selected skinfold measurements for calculating body fat percentage can vary based on gender. The choice of specific skinfold sites takes into account physiological characteristics and differences in fat distribution between men and women. Here are the recommended skinfold sites for each gender:
For Men:
- Triceps: Located on the back of the arm, halfway between the acromion (shoulder bone) and the olecranon (elbow tip).
- Chest: Measured on the midaxillary line, at the level of the nipple.
- Abdominal: Vertically, about 2 centimeters to the right of the navel.
For Women:
- Triceps: Same location as for men.
- Suprailiac: Area above the hip bone, on the midaxillary line, diagonally between the iliac crest (hip bone) and the midaxillary line.
- Thigh: On the front of the thigh, halfway between the hip and knee.
Step 2: Perform Measurements
To perform the measurements, you will need a skinfold caliper, a specific tool for this purpose. Follow these instructions for each skinfold:
- Hold the skinfold between your thumb and index finger, pulling the skin away from the underlying muscle.
- Position the skinfold caliper perpendicular to the fold, about 1 centimeter above the pinch point with your thumb and index finger.
- Press the skinfold caliper firmly but not excessively to ensure an accurate measurement.
- Read the skinfold thickness value on the caliper. Record this value in millimeters.
- Repeat this process for the three selected skinfold measurements.
Step 3: Calculate the Sum of Measurements
By adding the three measurements obtained from the skinfold sites (triceps, suprailiac, and thigh), you will have the total sum of skinfold thickness.
Step 4: Use the Pollock Formula to Estimate Body Fat Percentage
The Pollock formula provides an estimate of body fat percentage based on the measurements of the three skinfold sites. Here's the formula:
Body Density (Women) = 1.0994921 – 0.0009929*(Sum of Skinfolds) + 0.0000023*(Sum of Skinfolds)² - 0.0001392*(Age in years)
Body Density (Men) = 1.10938 – 0.0008267*(Sum of Skinfolds) + 0.0000016*(Sum of Skinfolds)² - 0.0002574*(Age in years)
Body Fat Percentage = [(4.95 / Body Density) – 4.50] x 100
In the formula above, the sum of skinfold measurements is the value obtained in Step 3.
Step 5: Interpret the Result
The value obtained using the Pollock formula represents an estimate of your body fat percentage.
How to Calculate Body Fat Percentage Using 7 Skinfold Measurements:
Step 1: Choose Measurement Areas
In the Pollock method, the seven selected skinfold measurements are: triceps (back of the arm), subscapular (below the shoulder blade), midaxillary (axillary region), suprailiac (above the hip), abdominal, thigh, and calf. Make sure these areas are accessible for measurement.
Step 2: Perform Measurements
Use a skinfold caliper to measure the skinfold thickness in each of the selected areas. Follow these instructions for each skinfold:
- Hold the skinfold between your thumb and index finger, pulling the skin away from the underlying muscle.
- Position the skinfold caliper perpendicular to the fold, about 1 centimeter above the pinch point with your thumb and index finger.
- Press the skinfold caliper firmly but not excessively to ensure an accurate measurement.
- Read the skinfold thickness value on the caliper. Record this value in millimeters.
- Repeat this process for each of the seven selected skinfold measurements.
Step 3: Calculate the Sum of Measurements
By adding the measurements obtained from each of the seven skinfold sites, you will have the total sum of skinfold thickness.
Step 4: Use the Pollock Formula to Estimate Body Fat Percentage
The Pollock formula provides an estimate of body fat percentage based on the measurements of the seven skinfold sites. Here's the formula:
Body Density (Women) = 1.097 – 0.00046971*(Sum of Skinfolds) + 0.00000056*(Sum of Skinfolds)² - 0.00012828*(Age in years)
Body Density (Men) = 1.112 – 0.00043499*(Sum of Skinfolds) + 0.00000055*(Sum of Skinfolds)² - 0.00028826*(Age in years)
Body Fat Percentage = [(4.95 / Body Density) – 4.50] x 100
In the formula above, the sum of skinfold measurements is the value obtained in Step 3, age is your age in years, and the sex value is 1 for men and 0 for women.
Step 5: Interpret the Result
The value obtained using the Pollock formula represents an estimate of your body fat percentage.
Keep in mind that these methods provide an estimation of body fat percentage and may have variations. For more accurate results and proper interpretation, it's recommended to seek guidance from a specialized professional such as a nutritionist or a fitness instructor.
Now you know how to calculate body fat percentage using 3 and 7 skinfold measurements. Remember to adopt healthy habits such as balanced nutrition and regular physical activity to achieve and maintain an appropriate body fat percentage for your health.
When to Use the Pollock Method with 3 or 7 Skinfold Measurements?
The choice between using the Pollock method with 3 or 7 skinfold measurements depends on the objectives and desired accuracy in assessing body fat percentage. Here are some general guidelines for each method:
- Pollock 3 Skinfolds: The 3 skinfold method is simpler and quicker to perform. It's suitable for an approximate estimate of body fat percentage in quick and routine assessments. It's less accurate than the 4 or 7 skinfold methods but can still provide a reasonable estimate in non-professional contexts.
- Pollock 7 Skinfolds: The 7 skinfold method is the most comprehensive and accurate of the three methods. It includes skinfold measurements of triceps, subscapular, midaxillary, suprailiac, abdominal, thigh, and calf. These seven sites are more representative of body fat distribution and can offer a more precise estimate of body fat percentage. The 7 skinfold method is commonly used in scientific research, clinical assessments, and by health professionals such as nutritionists, exercise physiologists, and personal trainers.
In summary, the Pollock 3 skinfold method is suitable for quick and non-professional assessments, while the Pollock 7 skinfold method is the most accurate and comprehensive. The choice of method will depend on the context, available resources, and goals of the body composition assessment.
Calculation of Body Fat Percentage According to Pollock (3 Skinfolds and 7 Skinfolds)
Measurements of skinfold thickness in body composition analysis are based on the observation that a significant portion of body fat is located in the subcutaneous tissue. Therefore, measurements of skinfold thickness serve as an indicator of the amount of fat localized in that region of the body. As fat distribution in the subcutaneous tissue is not uniform throughout the body, skinfold thickness measurements are taken in various regions to obtain a more detailed view of its distribution (Guedes & Guedes, 1998).
The anatomical points for taking skinfold thickness measurements include the regions of the biceps, triceps, subscapular, suprailiac, axillary, abdominal, thigh, and calf. The measurements vary depending on the predictive equation used to estimate body fat values (Pollock, 1993).
The obtained values are inserted into an appropriate formula to calculate the percentage of body fat. The chosen formula must take into account the individual's gender and age. Some formulas have also been developed for specific athletic groups (Williams, 2002).
Source: Comparative Study of Body Composition Determination Techniques - Keyla Brandão Costa - UFPE
Frequently Asked Questions
What is Body Density?
Body density is the relationship between the mass and volume of the body. It is a measure that indicates the compression of body tissues, such as muscles, bones, fat, and water. Body density can be used to estimate the percentage of body fat, which is an indicator of body composition and health status.
How is Body Density Measured?
There are different methods for measuring body density, varying in precision, complexity, and cost. Some examples include:
- Hydrostatic weighing: Involves weighing the individual both in and out of water, using the principle of Archimedes. It is considered a precise method but requires specific equipment and trained personnel.
- Plethysmography: Involves measuring body volume through variations in air pressure within a closed chamber. It is considered a precise method but requires sophisticated and expensive equipment.
- Bioelectrical impedance: Involves applying a low-intensity electrical current to the body and measuring the resistance offered by tissues. It is considered a practical and accessible method, but it depends on factors like hydration, temperature, and diet.
- Skinfold measurements: Involves measuring the thickness of skinfold folds in different body regions using an instrument called an adipometer. It is considered a simple and inexpensive method, but it depends on the evaluator's skill and the formula used to estimate body density.
What is the Ideal Body Density?
There is no single value for ideal body density as it depends on factors such as gender, age, genetics, and physical activity. Generally, higher body density corresponds to lower body fat percentage and higher lean mass percentage. However, it's important to consider that both insufficient and excessive fat can be harmful to health. Therefore, it's recommended to strive for a balanced composition and consult a specialized professional for proper assessment.
How to Interpret Body Fat Percentage?
Body fat percentage indicates the proportion of fat relative to the total body weight. It is an indicator of body composition and health status, as fat plays important roles in the body's functions, but can also pose risks when in excess or deficiency. Interpreting body fat percentage requires considering the individual's gender, age, and activity level. There are reference tables and classifications, but it's recommended to consult a specialized professional for a more accurate and personalized evaluation.
What are the Benefits of Having an Adequate Body Fat Percentage?
Having an adequate body fat percentage brings physical and mental health benefits, such as:
- Improving metabolism, immune system, and endocrine system function.
- Preventing and managing chronic diseases like diabetes, hypertension, high cholesterol, among others.
- Increasing muscular endurance, strength, and flexibility.
- Enhancing self-esteem, confidence, and emotional well-being.
- Reducing stress, anxiety, and the risk of depression.
How to Reduce Body Fat Percentage?
To reduce body fat percentage, adopting healthy habits that balance caloric intake and expenditure is essential. Some tips include:
- Following a balanced diet rich in fiber, protein, fruits, vegetables, and low in sugars, saturated and trans fats, salt, and processed foods.
- Drinking plenty of water throughout the day, avoiding sugary drinks, processed juices, and alcoholic beverages.
- Engaging in regular physical activity.
- Getting sufficient sleep to support recovery and regulate hunger and satiety hormones.
- Avoiding sedentary behavior, smoking, and excessive stress, which can negatively impact metabolism and contribute to fat accumulation.