From the Guidelines
The most accurate method for measuring body fat percentage is Dual-Energy X-Ray Absorptiometry (DXA), which is considered the gold standard due to its high accuracy and precision in differentiating between lean and fat tissues. According to the study by 1, DXA measures three compartments: fat mass, lean mass, and bone mass, and is a fast and noninvasive method that exposes the patient to acceptable radiation doses.
When considering the options for body fat percentage scanners, several methods are available, including:
- Dual-Energy X-Ray Absorptiometry (DXA)
- Bioelectrical Impedance Analysis (BIA)
- Air Displacement Plethysmography (ADP)
- Computed Tomography (CT)
Each method has its advantages and disadvantages, as outlined in the study by 1. For example, DXA is fast and noninvasive, but has variability between different devices and manufacturers, and hydration status can influence results. BIA is also fast and noninvasive, but only determines fluid-related compartments and fat is obtained by subtraction of FFM from body weight.
The study by 1 also highlights the accuracy of DXA in measuring body fat percentage, and notes that it is considered one of the "gold standards" for body fat assessment. However, it also notes that DXA may underestimate body fat at low body fat percentage and overestimate body fat at higher body fat percentage.
In terms of practical application, DXA is the recommended method for measuring body fat percentage due to its high accuracy and precision, although it may require a visit to a medical facility and is more expensive than other methods. For home use, BIA scales from brands like Withings, Renpho, or Tanita offer good accuracy for regular tracking at affordable prices. Consistency is key when using any scanner, and measurements should be taken at the same time of day, with similar hydration levels, and before eating or exercising for comparable results.
From the Research
Fat Percentage Scanner
- A fat percentage scanner, also known as bioelectrical impedance analysis (BIA), is a technique used to measure body composition, including body fat percentage 2.
- BIA is a relatively simple, inexpensive, and non-invasive method that can be used in field studies and larger surveys to estimate body fat percentage 2.
- The accuracy of BIA devices has been validated in several studies, which have shown high correlations between BIA estimates and dual-energy X-ray absorptiometry (DXA) measurements of body fat percentage 3, 4.
Types of BIA Devices
- There are different types of BIA devices available, including 4-limb and 2-limb foot-to-foot devices, which have been compared to DXA and magnetic resonance imaging (MRI) in terms of their accuracy in estimating body fat percentage 4.
- The 8-electrode BIA analyzer (BIA8MF) has been shown to accurately estimate total and segmental lean body mass, fat mass, and body fat percentage, with high correlations to DXA measurements 3.
Correlation with Anthropometric Indicators
- BIA estimates of body fat percentage have been correlated with anthropometric indicators, such as skinfold thicknesses, waist circumference, and waist-to-height ratio, which can be used as surrogates for body fat percentage when BIA is not available 5.
- The correlation between BIA estimates and anthropometric indicators can vary depending on the population being studied, with stronger correlations observed in some studies than others 5, 6.
Limitations and Considerations
- The accuracy of BIA devices can be affected by various factors, including population characteristics, age, and sex, which should be taken into consideration when interpreting BIA estimates 2, 6.
- The estimation of segmental bone mineral content based on BIA may not be reliable, and further research is needed to validate the use of BIA for this purpose 3.
- Short stature may impact the validity of body fat percentage estimates using anthropometric-based predictive equations, and BIA may be a more accurate method for estimating body fat percentage in older women with short stature 6.