Body Fat Composition Frequently Asked Questions

Why test body composition?
Growing research has demonstrated strong links between Body Composition and potential health risks such as:

• heart disease
• type II diabetes
• high blood pressure (hypertension)
• stroke
• certain types of cancer

What’s the difference between weight and body fat in terms of health risks?

Weight measurement alone cannot accurately determine a person’s body fat percentage and the resulting health risks. New evidence indicates that fat loss, not weight loss can extend lifespan.

Why is DEXA considered the “gold standard” in body composition measurement?

DECCA (Dual Energy Xray Absorptiometry ) is one of the most accurate clinical determinations of body composition and fat free mass. Its results have been validated through repeated scientific study and it is against which other clinical and field method results are evaluated. Quite simply, it is the benchmark for accuracy that other techniques attempt to attain.

What makes DEXA the method of choice for health care professionals and patients alike?

Accurate results and ease of use. Other available examinations of body fat and composition lack the impressive combination of accurate, reproducible measurements and simple, comfortable procedure boasted by DEXA Body Composition testing.

What are the alternatives to DEXA and why don’t they meet the gold standard?

Height – Weight Tables: This method was originally developed to establish recommended weight ranges based on mortality among large populations. The studies do not currently represent an accurate cross-section of the population and, thus, lack validity.

Body Mass Index (BMI): BMI is a simple calculation that determines height to weight ratios. It is a widely accepted method of obesity, but is often quite misleading in its results. Guidelines do not distinguish for gender, ethnicity or age and do not distinguish obesity or leanness for individuals who are extremely muscular.

Skin-fold Measurements: Generally speaking, skin-fold measurements are an inexpensive, easy, and portable method of body fat examination. However, results are very subjective as precision depends on the skill of the caliper technician, the site measured, and the quality of the calipers themselves.

Water Weighing: This technique involves first weighing a person under normal circumstances, then immersing them totally in water and weighing them again. Based on the fact that the densities of bone and muscles are greater than water and that fat is less dense than water, body density and body fat percentage can be calculated using standardized formulas. Despite its “gold standard” status, hydrodensitometry has several shortcomings. In some cases, athletes for example, denser than normal bones and muscles may lead to an underestimation of body fat percentage. In other cases, such as elderly patients suffering from osteoporosis, body fat may be overestimated. Additionally, many people find this method difficult, cumbersome, and uncomfortable; others are afraid of total submersion or cannot expel all the air in their lungs (an accuracy requirement of hydrodensitometry).

Bioelectrical Impedance Analysis (BIA): This method calculates body fat, fat free mass, hydration level, and other body composition values by passing a small electrical signal through the body. Impedance to the signal is greatest in fat tissue, while fat free mass allows it to pass much more easily. Hydration plays a large role in BIA calculations and levels outside the normal range can cause inaccurate results. Dehydration, which can be caused by not drinking enough fluids, drinking too much caffeine or alcohol, exercising or eating before testing, certain prescription drugs, illness or a woman’s menstrual cycle, often causes fat tissue to be overestimated by BIA.

Is DEXA Safe?

Yes, DEXA is a perfectly safe and harmless examination. The scanner emits a very low dose of radiation, which, in fact, is less than a daily dose from natural sources (cosmic radiation + environmental isotopes in our bodies and surroundings). Furthermore, DEXA produces 50 times less radiation than a standard x-ray examination. The procedure is relatively quick and only requires the patient to lie still on his/her back while the machine performs its functions.