Association between microstructure of ingestive behavior and body weight loss in patients one year after Roux-en-Y gastric bypass.

Roux-en-Y gastric bypass (RYGB) is one of the most effective procedures in the treatment of obesity. However, the predictive value of the microstructure of ingestion has not been widely investigated in this context. Here, we applied a recently developed drinkometer device to analyze the microstructure of ingestive behavior during a liquid meal in women and investigate whether it correlated with measures of weight loss after RYGB. Macro- and microstructural parameters of ingestive behavior of female patients (n = 24) one year after RYGB were measured in two different test sessions within a period of two weeks using the drinkometer. A Pearson correlation analysis was performed to compare the macro- and microstructural parameters of ingestive behavior with the percentage of total weight loss (%TWL), percentage excess BMI loss (%EBMIL), and body mass index (BMI) one year after RYGB, as well as age. A Bonferroni adjusted p < 0.003 was considered significant for the correlation analysis. For all other statistical tests, a p < 0.05 was considered significant. One year after surgery, a significant body weight loss was achieved in our study population (111.2 ± 15.6 kg vs 73.4 ± 11.7 kg; ***p < 0.001), with a mean%TWL of 33.8% (range: 20.4-48.6%). At the first test session,%TWL correlated with suck duration (r = 0.41, 0.05 > p > 0.003);%EBMIL correlated with both suck duration (r = 0.64, *p < 0.003) and inter-suck intervals (ISIs, r = -0.47, *p < 0.003), and, finally, BMI correlated with suck duration (r = 0.62, *p < 0.003) and ISIs (r = 0.48, *p < 0.003). However, at the second test session, no correlation was found between the body weight loss and the recorded ingestive parameters. Furthermore, no statistically significant difference was found in microstructural parameters of ingestive behavior between the two test sessions even though meal size decreased by 20% on the second visit (342.6.6 ± 167 kcal vs. 271.8 ± 142.8 kcal). A greater body weight loss of patients one year after surgery seems to be associated with longer suck duration and shorter ISIs, but only when the stimulus is tested for the first time by the study participants. This study contributes to the current knowledge about the ingestive behavior of bariatric patients one year after RYGB in terms of its association with the achieved weight loss. The use of the drinkometer device for the measurement of microstructure of ingestive behavior should be further expanded to different research questions and patient subgroups other than good responders. Its possible applications in clinical and behavioral research need to be included in the agenda of bariatric research.