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What Are 3 Methods of Assessing Body Fat?

Disease and Condition: Weight Loss
fat assessment
Besides the body mass index (BMI), here are the 3 most popular methods for assessing body fat.

Body fat percentage varies depending on factors such as age, gender, and level of fitness. Obesity and health problems, including heart disease, diabetes, and high blood pressure, may result from having more body fat. The body mass index (BMI) is the most basic and widely used method for calculating body fat. BMI, however, is not accurate in estimating body fat percentage.

Three of the most popular methods of determining body fat are:

  1. Skinfold measurements
    • This body fat test employs a skinfold caliper, which lightly pinches the skin and pulls fat away from muscles and bones.
    • The tester typically pinches three to seven different areas of the body, including the abdomen, the back of the arm, and the back of the shoulder.
    • To calculate body fat percentage, the thickness of each skinfold is entered into a formula.
      • Double-check the measurement by recording the thickness of each skinfold two or three times.
  2. Hydrostatic weighing (underwater weighing, hydrodensitometry, or immersion method)
    • The method involves measuring the body density based on the amount of water displaced when a person is submerged in water.
    • Fat has a lower density, so a person with a higher fat mass will displace more water and be more buoyant.
    • The person’s weight is first measured while on dry land.
    • They are then asked to exhale as much air as they can.
    • This is followed by completely submerging the person underwater and measuring their weight.
    • It is a highly accurate but time-consuming method to measure body fat percentage.
  3. Bioelectrical impedance analysis (BIA)
    • A small, safe electrical current is passed through the body in this method. 
      • Each type of body tissue (fat, muscle, bone, etc.) resists the flow of that current differently (a different impedance).
    • This impedance, along with a person's height, weight, age, gender, and general level of activity, is used to calculate body fat percentage.
    • While BIA is not as accurate as immersion, it produces good results.
      • The BIA equipment is simple to incorporate into a handheld measuring device or even a bathroom scale.

During your weight loss journey, your body weight shouldn’t be your main focus. Your body fat percentage tells you what comprises your weight, including fat mass and muscle mass.

What is a DEXA scan?

Dual-energy X-ray absorptiometry or DEXA scans are machines that radiologists use to assess bone mineral density in patients who are experiencing or at risk of bone loss (e.g., osteoporosis). These machines can identify both fat and lean mass.

Unlike other testing methods, DEXA scans provide information on body fat that is not confined to only subcutaneous fat (fat under the skin). Estimates of visceral fat (fat present deep inside the body around the abdominal organs) and intramuscular fat are included in the DEXA scan results.

DEXA scans go a step further by revealing the body composition by body region. The scan findings show the amount and percentages of fat, lean mass, and bone in each of the following body segments:

  • Left and right arms
  • Left and right legs
  • Left and right trunk (i.e. the rib cage region)
  • Android (i.e. the lower abdomen region)
  • A gynoid (i.e. the pelvic region)
  • Head

DEXA scan reports provide more than just an overall body composition reading. They show how mass is distributed throughout the body, including where the fat is stored, and how much lean and bone mass is in each body region.

What is the healthy body fat percentage?

The healthy levels of body fat percentage vary with several factors, including age and gender. To know if the body fat content is healthy, it is advisable to ask a healthcare professional.

Table. The approximate range of body fat percentage for various age groups
Age group Healthy body fat percentage (%)
Males Females
20 to 39 years 8 to 19 21 to 32
40 to 59 years 11 to 21 23 to 33
60 to 78 years 13 to 24 24 to 35

QUESTION

Weight loss occurs in the belly before anywhere else. See Answer
References
Duren DL, Sherwood RJ, Czerwinski SA, et al. Body Composition Methods: Comparisons and Interpretation. J Diabetes Sci Technol. 2008;2(6):1139-1146. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2769821/

Harvard T. H. Chan. Measuring Obesity. https://www.hsph.harvard.edu/obesity-prevention-source/obesity-definition/how-to-measure-body-fatness/

Hill JW. A Comparison of Percent Body Fat Calculated by Three Methods: Hydrostatic Weighing, Skin Folds, and Near Infrared Technique. Western Michigan University. Master's Theses. 1992; 877. https://scholarworks.wmich.edu/cgi/viewcontent.cgi?article=1876&context=masters_theses

Winchester Hospital. Your Body Fat Percentage: What Does It Mean? https://www.winchesterhospital.org/health-library/article?id=41373

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