Examination of the two‐step water load test as a measure of gastric interoception and associations with eating and weight/shape concerns in a nonclinical sample

Abstract Objective The current study extended research examining the validity of the two‐step Water Load Test ( WLT‐II ), an objective, laboratory‐based measure of gastric interoception, by investigating the validity of the WLT‐II in a nonclinical sample and testing its contribution to the prediction of eating and weight/shape concerns. Methods Participants ( n = 129, 73.6% cisgender female, M = 20.13 years old) completed the WLT‐II Questionnaire and two‐step WLT‐II, as well as self‐report measures of eating and weight/shape concerns (Eating Disorder Examination Questionnaire; EDE‐Q) and interoception (Multidimensional Assessment of Interoceptive Awareness‐2; Intuitive Eating Scale‐2 Reliance on Hunger and Satiety), in the lab at a large southeastern university. Data analysis included repeated measures ANOVA, correlations, and a series of hierarchical linear regressions. Results Participants reported considerably more discomfort after the “maximum fullness” trial compared to the “satiation” trial. The WLT‐II's objective measure of gastric interoception (sat_%) was not significantly correlated with the self‐report measures of interoception and did not predict EDE‐Q Dietary Restraint, Eating Shame, or Weight/Shape Concerns. Unexpectedly, greater gastric sensitivity was associated with less EDE‐Q Preoccupation/Restriction. Exploratory analyses suggested a possible nonlinear association. Discussion These results support the validity of the WLT‐II in its ability to create, measure, and distinguish between the states of satiation and maximum fullness. However, results also suggest additional work is needed to better understand what the WLT‐II's sat_% measure is capturing, as well as investigate potential nonlinear associations of the WLT‐II with disordered eating. Public Significance Interoception, or the processing of internal body signals, shows important links to disordered eating. Despite the clear relevance of gastric interoception to disordered eating—such as the ability to detect satiety signals—existing research has relied on general, self‐report measures of interoception. This study examined the utility of a laboratory‐based measure of gastric interoception. Results suggested mixed support for its validity and utility for predicting eating and weight/shape concerns in a nonclinical population.