Following Roux-en-Y Gastric Bypass (RYGB) patients tend to achieve significantly higher blood alcohol concentrations (BACs) and they reach peak concentrations much more rapidly than before surgery. The overall exposure to alcohol as represented by the area-under-the-curve (AUC), however, has generally not changed from before to after surgery. This study examined the extent to which patients could accurately estimate their BAC before and after surgery, as this may have implications for additional risks associated with drinking alcohol.


19 participants (78.9% female; MAge = 37.5 years) completed a pharmacokinetic assessment of ethanol before and one year following RYGB surgery. BACs were measured at specific intervals over 180 minutes following a dose (0.3 g/kg) of alcohol. Participants also provided estimations of their perceived level of alcohol intoxication concurrent with 11 of these assessments. AUC was calculated for both observed (AUC-O) and perceived (AUC-P) BAC levels.


Paired-samples t-tests demonstrated that pre-surgery AUC-P was greater than post-surgery AUC-P (p = .046), but no significant difference between the pre-and post-surgery AUC-O emerged (p = .560). Further, bivariate correlations revealed no significant relationship between the AUC-O and AUC-P at both the pre- and post-surgery timepoints (p's > .277).


These results suggest that, even though AUC-O was largely equivalent over time at pre- and post-surgery, participants perceived themselves to be more intoxicated than they actually were prior to surgery. Further, participant estimations of BAC were, on average, not accurate when compared to their actual level of intoxication at both pre- and post-surgery.