Can a DXA Scan Measure Visceral Fat?

It’s been long known that disease risks are higher in those who accumulate fat in the abdominal region, independent of the amount of total body fat. For that reason, many public health experts recommend weight loss especially from the abdominal areas. Given this, it’s important to have a method that can measure abdominal fat so that someone’s risk can be classified and their progress in changing their fat levels be documented. Many body composition assessment methods are accurate in measuring total body fat but have higher errors when measuring regional fat (if they are recommended for that purpose at all). Let’s examine a popular body composition method: Dual-energy X-ray Absorptiometry (DXA).  

DXA is a method of body composition assessment that uses low levels of X-ray to distinguish between bone, fat and lean mass. Regional scans at the hip and spine are routinely used to assess bone mineral density and total body scans give percent body fat. But it is possible to get regional composition from this total body scan. DXA is an accurate and highly precise method for total body composition and has been used to estimate visceral fat.  

The two major companies who manufacture DXA devices, GE Lunar (Madison, WI) and Hologic (Waltham, MA), have developed fully automated methods for estimating visceral fat (Kaul, 2012 & Micklesfield, 2012). But do they work? Remember that DXA only measures in 2 dimensions and never measures depth. And DXA technology does not provide images in cross-sectional slices like CT or MRI scans. In fact, CT or MRI are the criterion methods for measuring visceral fat.  

A systematic review and meta analysis by Murphy (2019) examined agreement between intra-abdominal adipose tissue (IAAT) mass, thickness and volume and the same variables measured by either CT or MRI. They found that DXA agreed well, especially for IAAT volume. They also noted that the percent error is greater for those with lower levels of fat. DXA’s ability to quantify the amount of visceral fat is important for identifying those who may be at risk for cardio- metabolic diseases.  

Recently, Meredith-Jones (2021) compared DXA derived visceral fat to cardio- metabolic risk factors and attempted to determine cut off values that could be used clinically. They found that DXA visceral fat measures were strongly related to elevated blood lipids and blood pressure as did total body percent fat. Further, cut off values were identified that discriminated between those people at low risk versus high risk of cardio-metabolic disease.  

DXA’s ability to measure visceral fat has clinical value, especially since it can be derived from a total body scan that also gives other valuable information that can inform health. One caution is that the ability to provide useful information clinically does not mean that DXA derived visceral fat can replace fat measures from CT or MRI for uses such as research.  

References:
Kaul S, Rothney M, Peters D, Wacker W, Davis C, Shapiro M, Ergun D. Dual-energy x-ray bsorptiometry for quantification of visceral fat. Obesity (2012) 20, 1313–1318.  

Meredith-Jones K, Taylor R, Brown R, Cooke R, Vlietstra V, Poulton R, Haszard J. Age- and sex-specific visceral fat reference cutoffs and their association with cardio-metabolic risk. Int J Obesity (2021) 45, 808–817.  

Micklesfield L, Goedecke J, Punyanitya M, Wilson K, Kelly T. Dual-energy x-ray performs as well as clinical computed tomography for the measurement of visceral fat. Obesity (2012) 20, 1109–1114.  

Murphy J, Bacon S, Morias J, Tsoukas M Santosa S. Intra-abdominal adipose tissue quantification by alternative versus reference methods: A systematic review and meta- analysis. Obesity (2019) 27, 1115-1122.