Allometric relationship between changes of visceral fat and total fat mass

Objective: To elucidate the mathematical relationship between changes of visceral adipose tissue (VAT) and total body fat mass (FM) during weight loss. Design: We hypothesized that changes of VAT mass are allometrically related to changes of FM, regardless of the type of weight-loss intervention, as defined by the differential equation dVAT/dFM = k x VAT/FM, where k is a dimensionless constant. We performed a systematic search of the published literature for studies that included measurements of VAT changes via magnetic resonance imaging (MRI) or computed tomography (CT) imaging along with measurements of FM changes by dual-energy X-ray absorptiometry, hydrodensitometry, air-displacement plethysmography or whole-body MRI or CT imaging. We then examined whether or not the data could be explained by the allometric model. Result: We found 37 published studies satisfying our search criteria, representing 1407 men and women of various ethnicities, degrees of adiposity and weight-loss interventions. The hypothesized allometric equation relating changes of VAT and FM accurately modeled the data for both men and women and for all methods of weight loss studied. The best-fit value for the dimensionless constant was k = 1.3 +/- 0.1 and the resulting model had an R-2 = 0.73. Conclusion: This is the first report to reveal an allometric relationship between changes of VAT and FM that holds for both genders as well as a wide variety of weight-loss interventions including bariatric surgery, caloric restriction with or without exercise and exercise alone. We conclude that changes of VAT are primarily determined by FM changes as well as the initial VAT to FM ratio.