3. Discussion
obesity, weight loss
OBESITY, SEPARATION
The aim of our study was to identify and characterize a comprehensive metabolomic profile, which highlights the effect of bariatric surgery on the metabolome beyond weight loss. Whereas patients of the WAS intensified lifestyle group failed to lose weight significantly, patients with bariatric surgery lost a significant amount of their body weight as expected. To clarify the role of RYGB-induced body weight loss itself, the same metabolomic parameters were analyzed in rats treated with RYGB or a similar effective food restriction regime.Examining the Sphingolipids maintain lipid microenvironments of plasma membranes and form lipid rafts [A further metabolomic subgroup included BCAA, and aromatic amino acids. The BCAAs could be identified as a valid separator of the LS and OP group at one year after randomization. As described before, BCAAs correlate with BMI and HOMA-IR [Analyzing overlapping phosphatidylcholines from the metabolomic profiles as a translational approach with indirect comparison, PC aa C42:Ys have been identified as being significantly different metabolites in both comparisons, OP vs. LS and RYGB_rat vs. BWM_rat. PC aa C42:Ys, better known as lecithins, have been repeatedly mentioned in studies investigating metabolomics in obesity [The analysis of the metabolomics of rats with similar body weights after RYGB and diet restriction and similar food composition overcomes the limitation that weight loss effects cannot be differentiated from the effects of the bariatric intervention (i.e., changed absorbance) itself. Interestingly, lipids play a crucial role in differentiating RYGB from BWM rats, while amino acids do not facilitate the separation of these intervention groups. Therefore, changes in BCAAs after RYGB do not seem to be caused by bariatric surgery itself. A significant increase in sphingolipids as well as PC aa C42:Ys in the OP group of the WAS trial and higher levels in the BWM vs. RYGB group of our animal experiment were detected. The role of sphingolipids in obesity and IR is not fully understood and has to be investigated in further Our study has several limitations. The very low sample size compared to the large number of analyzed metabolites may have hampered the interpretation of data. It was also not possible to consider the whole spectrum of confounders (e.g., smoking status) potentially influencing the metabolic spectrum. Although there was no difference in the nutrition counseling, we cannot exclude that the actual nutrition might have differed from the references within the nutrition counseling. Additionally, gender distribution differed significantly between the LS and OP group of the WAS cohort. Furthermore, a direct comparison of 