"Feeling fat," the somatic sensation of being overweight that does not entirely correlate with one's actual weight, is recognized clinically as a maintenance factor in eating disorders. Occurring amidst Western internalized thin ideals and weight stigma, "feeling fat" is wide-reaching and also reported by those with subclinical and absent eating pathology. However, empirical study of "feeling fat" is limited. Regarding proposed mechanisms, "feeling fat" may (a) reflect the displacement of negative affect onto the body, (b) represent one element of a cognitive distortion related to the imagined consumption of fattening food, and/or (c) be a function of impaired interoceptive awareness. However, the relative and/or joint contributions of these mechanisms to "feeling fat" are unclear. Regarding measurement, retrospective assessment with single items has been the norm. Innovative measures of "feeling fat" will expand our understanding of this construct. Ecological momentary assessment can clarify the transitory nature of this experience, and physiological measures can allow for assessment of somatic elements of "feeling fat. Multi-method and implicit measurement strategies of 'feeling fat'" may clarify the mechanisms underlying this experience. Further research with improved measurement techniques may also benefit eating disorder treatment by highlighting new treatment foci (e.g., cognitive distortions, interoceptive awareness).