Background

Changes in visceral adipose tissue (VAT) following laparoscopic gastric bypass surgery (LRYGB) in adolescents have not been described. We hypothesized that VAT would be significantly reduced following LRYGB and that degree of VAT reduction would be more closely associated with improvements in cardiometabolic risk factors than changes in total body fat (BF%) and BMI among adolescents with severe obesity.

Methods

59 adolescents with severe obesity (18 male; mean age 16.3 years; mean BMI 43.3kg/m2) undergoing LRYGB had body composition measured using dual x-ray absorptiometry (DXA) analysis pre-operatively and at 1- and 5-yr follow up post-operatively. The association of change in VAT, BF%, and BMI with cardiometabolic risk factors (ALT, HbA1c, insulin, LDL, HDL, TG, hsCRP, systolic blood pressure [SBP]) was assessed using multiple linear regression analysis and generalized estimating equations adjusting for age, sex, and baseline risk factor levels. Date are presented as mean(SD).

Results

Mean BMI at baseline (43.3[4.6]kg/m2) decreased to 30.0(4.2)kg/m2 at 1-yr post-op(p<0.001), rising to 31.6(5.8)kg/m2 at 5-yr (p=0.013). Mean VAT at baseline was 1886(809)g which decreased to 639(353)g at 1-yr post-op (p<0.001) and remained stable at 5-yr (726[578]g, p=0.11). Mean BF% at baseline was 52(4)% which deceased to 39(7)% at 1-yr post-op (p<0.001) and was stable at 5-yr (40[9]%). Despite the significant reductions in VAT, BMI, and BF%, no statistically significant association with risk factors were observed at 1 year, except for BF% was modestly associated with changes is LDL (b=-0.01[-0.02,0.0], p=0.042). Baseline VAT, BMI, and BF% were not with 5 year change in any cardiometabolic risk factors.

Conclusions

VAT, BF% and BMI are all decreased markedly in the first year following LRYGB and remained relatively stable out to 5-yr post-surgery. Despite this reduction, neither VAT, BF% or BMI were associated with changes in cardiometabolic risk factors observed, suggesting a potential alternative mechanism.