The Eating Inventory (EI) is commonly used to measure a range of eating behaviors. It includes three subscales: Cognitive Restraint, Hunger, and Disinhibition. In this study, we decomposed the variance of the three subscales, and evaluated the genetic, common environment and specific environmental effects on each in a sample of female-female twin pairs. Multivariate models were also used to examine whether the EI represented three individual factors, or whether there was extensive covariance among subscales. Heritabilities were estimated at 45% (CI of 32–57%) for Disinhibition, 8% (CI of 0–38%) for Hunger, and 0% (CI of 0–30%) for Restraint. Common environmental influences were estimated at 0% (CI of 0–23%) for Disinhibition, 16% (CI of 0–34%) for Hunger, and 31% (4–42%) for Restraint. Specific environmental influences accounted for the rest of the variance of the subscales. However, multivariate modeling indicated that Disinhibition and Hunger covaried significantly, indicating that these two subscales are influenced by the same set of genetic factors. Furthermore, Restraint appeared to be empirically distinct from Hunger or Disinhibition.