What is Visceral Adipose Tissue (VAT)?
Visceral adipose tissue or VAT is the intra-abdominal fat that is located inside the abdominal cavity and is packed between the organs (stomach, liver, intestines, kidneys, etc.) Visceral fat is different from subcutaneous fat, which is located just underneath the skin. Until recently, we were only able to measure VAT using magnetic resonance imaging (MRI) or computed tomography (CT).
Recent advances in dual X-ray absorptiometry (DXA) now allow you to measure VAT using DXA in a variety of populations (1, 2, 3, 4). So what is so important about VAT? For overall health, an excess of VAT is an established marker for both cardiovascular and metabolic diseases (3, 5, 6, 7, 8), independent of subcutaneous abdominal fat and total body fat. But a VAT measurement for athletes may provide additional information for athletic performance.
Why is VAT Important for Athletes?
So what does VAT have to do with athletes and performance? Abdominal obesity has been associated with increased risk of lower-body musculoskeletal injuries (9, 10). So athletes carrying large amounts of VAT are at an increased risk for injury. A recent study published by our group also demonstrated that when athletes reach a certain threshold of body weight, increased gains in weight disproportionately accumulate as VAT.
While some coaches may want their athletes to weigh more in a short time frame, that additional weight may accumulate as VAT. Not only does this potentially increase the risk for cardiovascular and metabolic diseases, but it also increases risk of injury. Monitoring of VAT is a way to track weight gain to make sure that the additional weight is healthy for an athlete. Examining VAT levels is also another way to monitor cardiovascular and metabolic risk factors.
Why do VAT Levels Differ Widely from DXA Manufacturers?
If you have looked at VAT values from different DXA manufactures, you may notice the levels differ widely from manufacturer to manufacturer. The reason for these differences in VAT is that each DXA manufacturer has different methodology of calculating the VAT value. For example, a Hologic DXA scanner estimates VAT mass as an area that lies in the L4–L5 vertebral region while the GE iDXA scanner estimates VAT mass as a volume that lies in the android region. For this reason, the two measures of VAT differ, but by using DXA to measure VAT, the differences between one scan to another using the same machine will be accurate and precise.
Bosch TA, Burruss TP, Weir NL, Fielding KA, Engel BE, Weston TD, Dengel DR: Abdominal body composition difference in NFL football players. Journal of Strength and Conditioning Research 28(12):3313-3319, 2014.
Bosch TA, Chow L, Dengel DR, Melhorn SJ, Webb M, Yancey D, Callahan H, De Leon MRB, Tyagi V, Schur EA: In adult twins, visceral fat accumulation depends more on exceeding sex-specific adiposity thresholds than on genetics. Metabolism 64:991-998, 2015.
Bosch TA, Dengel DR, Kelly AS, Sinaiko AR, Moran A, Steinberger J: Visceral adipose tissue measured by DXA correlates with measurement by CT and is associated with cardiometabolic risk factors in children. Pediatric Obesity 10:172-179, 2015.
Bosch TA, Steinberger J, Sinaiko AR, Moran A, Jacobs DR, Kelly AS, Dengel DR: Identification of sex-specific thresholds for accumulation of visceral adipose tissue in adults. Obesity 23:437-444, 2015.
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Kaess, BM, Pedley, A, Massaro, JM, Murabito, J, Hoffmann, U, Fox, CS. The ratio of visceral to subcutaneous fat, a metric of body fat distribution, is a unique correlate of cardiometabolic risk. Diabetologia 55: 2622–2630, 2012.
Katzmaryk, PT, Heymsﬁeld, SB, Bouchard, C. Clinical utility of visceral adipose tissue for the identiﬁcation of cardiometabolic risk in white and African American adults. American Journal of Clinical Nutrition 97: 480–486, 2013.
Murphy, DF, Connolly, DAJ, and Beynnon, BD. Risk factors for lower extremity injury: A review of the literature. British Journal of Sports Medicine 37: 13–29, 2003.
Nye, NS, Carnahan, DH, Jackson, JC, Covey, CJ, Zarzabal, LA, Chao, SY, Bockhorst, AD, and Crawford, PF. Abdominal circumference is superior to BMI in estimating musculoskeletal injury risk. Medicine & Science in Sports & Exercise 46(10) 1951-1959, 2014.
About the Author: Donald Dengel, Ph.D., is a Professor in the School of Kinesiology at the University of Minnesota and is a co-founder of Dexalytics. He serves as the Director of the Laboratory of Integrative Human Physiology, which provides clinical vascular, metabolic, exercise and body composition testing for researchers across the University of Minnesota.