Short-term dynamics and metabolic impact of abdominal fat depots after bariatric surgery

OBJECTIVE - Bariatric surgery is gaining acceptance as an efficient treatment modality for obese patients. Mechanistic explanations regarding the effects of bariatric surgery on body composition and fat distribution are still limited. RESEARCH DESIGN AND METHODS - Intra-abdominal and subcutaneous fat depots were evaluated using computed tomography in 27 obese patients prior to and 6 months following bariatric surgery. Associations with anthropometric and clinical changes were evaluated. RESULTS - Excess weight loss 6 months following surgery was 47% in male and 42.6% in female subjects. Visceral fat and subcutaneous fat were reduced by 35% and 32%, respectively, in both sexes, thus the visceral-to-subcutaneous fat ratio remained stable. The strongest relation between absolute and relative changes in visceral and subcutaneous fat was demonstrated for the excess weight loss following the operations (r ∼ 0.6-0.7), and these relations were strengthened further following adjustments for sex, baseline BMI, and fat mass. Changes in waist circumference and fat mass had no relation to changes in abdominal fat depots. All participants met the criteria of the metabolic syndrome at baseline, and 18 lost the diagnosis on follow-up. A lower baseline visceral-to-subcutaneous fat ratio (0.43 ± 0.15 vs. 0.61 ± 0.21, P = 0.02) was associated with clinical resolution of metabolic syndrome parameters. CONCLUSIONS - The ratio between visceral and subcutaneous abdominal fat remains fairly constant 6 months following bariatric procedures regardless of sex, procedure performed, or presence of metabolic complications. A lower baseline visceral-to-abdominal fat ratio is associated with improvement in metabolic parameters.