What is Body Composition Testing?

DXA Body composition testing (BCT) is the “gold standard” for measuring the distribution of body fat, muscle, and bone mass. BCT is the most accurate in determining the percentage of fat within the body utilizing a very minimal amount of radiation.

Unlike other body composition tests utilizing the body mass index (BMI), this body composition test utilizes fat mass index (FMI). Fat mass index is more accurate because it takes the amount of bone, fat, and muscle into the calculation in addition to age, height, gender, weight and ethnicity; age and ethnicity are not in the BMI evaluation.

Body composition is important in the evaluation of many diseases and can help to stratify (quantify) risk. Examples of these diseases include obesity, diabetes, cardiovascular risk assessment, and anorexia.

Learn why the dxa scan is the best

body composition testing


  1. If you are trying to lose weight & want to monitor body fat loss and muscle growth from exercise, DXA is an accurate way to see the effectiveness of your weight management and fitness programs.
  2. If you are proactive in your health and want to reduce the risks of heart disease, diabetes, high blood pressure, high cholesterol, cancer and obesity – a DXA scan is a positive first step.
  3. If you are an athlete or bodybuilder and you’re trying to increase your muscle to fat ratio, you can use DXA to track your progress in building muscle while losing your body fat, muscle atrophy from injury, as well as muscle gain during rehabilitation.
  4. Following an injury and during rehabilitation, DXA can track muscle atrophy and your progress during rehabilitation/physical therapy.

What will dxa body composition tell me?

FMI – Fat Mass Index

A new way of classifying obesity that takes your gender, age, ethnicity and height into consideration.


Severe fat deficit Moderate fat deficit Mild fat deficit Normal Excess fat Obesity class I Obesity Class II Obesity Class III
Men <2 Women <3.5 Men 2-<2.3 Women 3.5-<4 Men 2.3-<3 Women 4-<5 Men 3-6 Women 5-9 Men >6-9 Women >9-13 Men >9-12 Women >13-17 Men >12-15 Women >17-21 Men >15 Women >21

VAT – Visceral Adipose Tissue

This value reflects the amount of body fat (deep fat) which is stored within the abdomen, wrapping around major organs such as the kidneys, liver and pancreas.

VAT Standards

Normal Increased Risk High Risk
10-100 101-160 161-300

Truth about visceral fat

Total body fat %

Lean Tissue By Extremity

The DXA scan can also play an important role in assisting symmetrical muscle developments for athletes of all sports. The data provides information on muscle mass and bone density for the entire body, which can be used to alter an athlete’s training program to gain more symmetry and ultimately prevent injury. Once training adjustments have been made, the DXA scan can continue to track progress.

RMR – Resting Metabolic Rate

RMR represents the minimum amount of energy required to keep your body functioning. As an example, with a resting individual, how many calories does your body need to maintain the various bodily functions?

Calculate your RMR


This value is a predictor for possible metabolic or cardiovascular disease. Android (or truncal) obesity is associated with higher individual risk of metabolic or cardiovascular disease.


Pear-shape Apple-shape
<100 >100


The BCT procedure by DXA is simple. It utilizes high and low energy x-ray scans with very low radiation dose. You will lie on a padded table for about 10 minutes while the scanning is completed. The evaluation includes the three tissue components: bone mass, fat mass, and lean mass.

The only preparation indications are:

  1. You are not pregnant
  2. You have not recently had imaging exams using oral contrast or a radioactive isotope

At your appointment we will ask you to remove all metal (including rings) and to empty your bladder. Additionally, we will obtain your height and weight prior to scanning.


There are a variety of indications for the use of DXA BCT. These indications include the following:

  • Bariatric, including weight loss programs, management of obesity, and bariatric surgery
  • Management of anorexia;
  • Female athlete triad (low bone mass. amenorrhea, energy imbalance);
  • Malnutrition/nutritional status;
  • Sarcopenia of aging;
  • Sports management and performance;
  • Pediatric patients;
  • Lipodystrophy with HIV treatment.

Diagnostic Findings

Diagnostic information with BCT is obtained with a direct comparison to gender and ethnicity specific reference data developed from the National Health and Nutrition Examination Survey (NHANES) data documented on the Centers for Disease Control & Prevention (CDC) website. The data contains over 20,000 subjects ages 8 – 85.

The NHANES body composition reference database represents one of the largest peer-reviewed studies ever undertaken and our Hologic DXA scanner has been shown to be the most accurate tool for body composition testing relative to the NHANES database.


Health Fitness Diagnostics at Pueblo Radiology is please to offer this state-of-the-art technology. As preventative care becomes the focus for a healthy life, we believe our BCT service offers a cost-effective and important option for the community.

Whether you are seeking high levels of fitness or just trying to lose a few pounds, we encourage you to start by setting an appointment for a BCT today. We hope you will find us a key partner in your health goals.